Flours Based on Exotic Fruits and Their Processing Residues—Features and Potential Applications to Health and Disease Prevention

C H A P T E R

30 Flours Based on Exotic Fruits and Their Processing Residues—Features and Potential Applications to Health and Disease Prevention Laı´s M. Resende*, and Adriana S. Franca† †

*Food Science Graduate Program, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil Mechanical Engineering Department, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil

O U T L I N E Introduction

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Overview of Exotic Fruits and Their Processing Residues Used for the Production of Flours

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Production Techniques of Exotic Fruit Flours

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Potential Applications to Health and Disease Prevention: In Vitro, Experimental, and Clinical Studies

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Prospects for Future Research

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Concluding Remarks

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Features of Flours Based on Exotic Fruits and Their Processing Residues

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Summary Points

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Technological Properties and Applications in Food

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References

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Abbreviations AOAC Association of Official Agricultural Chemists DF dietary fiber GAE gallic acid equivalents HF high fat HPLC high-performance liquid chromatography UPLC ultra-performance liquid chromatography

INTRODUCTION It is widely accepted by the scientific community that dietary fiber (DF) and phytochemical intake are associated with a reduced risk of chronic diseases, such as cardiovascular diseases, type 2 diabetes, obesity, and cancer. However, supplementation of purified, biologically active components does not always achieve the expected results. Some researchers argue that the health benefits are attributed to synergy among the components existing in whole foods. A varied diet increases the health benefits and reduces the risks of toxicity, since plant foods include many different types of phytochemicals in varying amounts.1–3 Fruits are important sources of DFs and phytochemicals. Compared to cereals, fruits tend to present a better ratio between soluble and insoluble fibers and higher amounts of associated bioactive compounds.4 Liu1 argues that natural antioxidants from fruits are more effective than purified phytochemical supplements. On the other hand, it has been established that fruits present high moisture values and are very perishable. Drying is a good option to extend the shelf

Flour and Breads and their Fortification in Health and Disease Prevention https://doi.org/10.1016/B978-0-12-814639-2.00030-7

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© 2019 Elsevier Inc. All rights reserved.

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life of fruits. The production of fruit flours is an alternative to drying. Many types of fruit flour product can be found in the market. Commercial unripe banana, apple, and grape are the more common types of fruit flours. These flours are tested as an ingredient in various foods as an additive or as partial replacement for cereal flours. Most researchers investigate changes in nutritional composition and technological properties of those new food products. Agama-Acevedo et al.5 developed cookies with partial replacement of wheat flour by unripe banana flour. The resulting product was found to contain a higher amount of resistant starch (RS) content and a lower glycemic index (GI), showing to be a potential nutritional alternative for people with health problems such as diabetes and obesity. Given the nutritional appeal of this type of product, other studies were conducted. Sardá et al.6 assessed the RS content of unripe banana flour marketed in Brazil, and they emphasized the importance of adding information on the high variety encountered (4%–62%) to the label. Casarotti and Penna7 added 1% of commercial apple, banana, and grape flours to fermented milk and observed a protective effect of fruit flours on the simulated gastrointestinal tolerance of culture probiotics. Fruit by-products can be also used to prepare flours. The use of by-products would provide alternative uses for the large amount of by-products wasted by the agro-industry. O’Shea et al.8 prepared two types of flour from apple and orange pomaces obtained from the juice industry. The pomaces were freeze-dried and milled for preparation of the flour. Orange pomace flour showed a high water hydration capacity, while apple pomace flour presented viscoelastic properties that could enhance structures within foods. Urquiaga et al.9 observed favorable clinical changes (improvement of blood pressure, glycemia, and postprandial insulin; increased antioxidant defenses; and decreased oxidative protein damage) in adult men, with one or more metabolic syndrome components, who consumed 20 g of red wine grape pomace flour per day for 16 weeks. Those effects were attributed to the fibrous and polyphenolic composition of the flour. O’Shea et al.10 wrote about the most current gluten-free research and discussed the role of fruit processing by-products as gluten-free flours. Examples include green banana, orange, and apple pomace flours employed in the production of gluten-free pasta, bread, and extruded puffed snacks, respectively. Flours based on fruit by-products have the potential to be incorporated into a wide variety of gluten-free foods and to improve the nutritional composition, structure and flavor of the foods; in addition, they are cheaper. However, some limitations need to be considered, such as that they are more suited to specific foods and preprocessing needs, indicating that more studies in this area are needed.10 Despite the variety of research on the application of fruit flours as food-product ingredients, these products have not yet conquered their market potential. The commercial product that can be found more commonly are the so-called fruit flours. These products have several denominations, such as “fruit name seed/skin” flour (e.g., grape flour, grape seed flour, and grape skin flour), “fruit name” powder (e.g., mango powder), “fruit name” dried fruit pulp (e.g., baobab dried fruit pulp), or even “fruit name” fiber (e.g., orange fiber). Notwithstanding these names, processing is what qualifies the products as flours. In all cases, one must use the whole raw material and one should not isolate compounds, such as DF. In Brazil, the flour legislation, RDC No. 263, passed on September 22, 2005,11 considers flour to be products obtained from the edible parts of different plants, including fruits, which are subjected to milling and/or other technological processes safe for food preparation. Following the trend of fruit flours, exotic fruits quickly became the focus of research and are already entering the market. Exotic fruits are tropical and subtropical fruits that are not commonly found in global markets, but they have the potential for this purpose due to nutritional and sensory characteristics.12 Exotic fruits are species that appear spontaneously only in some regions, and they may present some local cultivation, restricted to a specific population. However, as Rufino and collaborators13 discussed, due to the high nutritional and therapeutic values of these fruits, consumption has increased both in domestic and international markets. Exotic fruit flours, therefore, are a great alternative for market expansion of otherwise perishable products (i.e., the fruit itself). Nonetheless, not only the pulps of exotic fruits have been studied for the production of flours, processing residues of these fruits have also been identified as potential sources of food additives. Exotic fruit consumption and processing have been increasing worldwide, and that the fruit-processing industry generates a large amount of by-products that can have similar or higher content of bioactive compounds than the main product.11 Thus, a number of studies have investigated the potential of peels, seeds, brans, and other residues from the exotic fruit agro-industry in the production of flours. Some examples of exotic fruits include ac¸ai/assaí (Euterpe oleracea Mart.), buriti (Mauritia flexuosa L.f.), and pequi (Caryocar brasiliense A.St.-Hil.), which are native to South America; baobab (Adansonia digitata L.), native to subSaharan Africa; and durian (Durio zibethinus L.), from Southeast Asia. In this chapter, relevant points regarding studies on exotic fruit flours are discussed, such as production techniques, chemical and technological features, potential applications to health and disease prevention, toxicity, and suggestions for future research.

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OVERVIEW OF EXOTIC FRUITS AND THEIR PROCESSING RESIDUES USED FOR THE PRODUCTION OF FLOURS

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OVERVIEW OF EXOTIC FRUITS AND THEIR PROCESSING RESIDUES USED FOR THE PRODUCTION OF FLOURS The concept of exotic species is much discussed by ecologists in relation to origin, adaptation, and damage to ecosystems.15 However, the concept addressed here is related to access to cultural species by certain communities and places that are neither naturally found nor cultivated globally. However, despite this restriction of access to the natural product, the species can be marketed in the form of a processed product in response to a market that demands new foods with high nutritional and even therapeutic value. Flours are a great strategy for preserving fruits. It is known that high water activity, which is common to fruits, causes it to be easily susceptible to microbial attack. Furthermore, their voluminous nature can hinder transportation. Another advantage of using flours, especially in the case of exotic fruits, is that availability is guaranteed in all seasons (wild native fruits are not available year round). Thus, research on the production of exotic fruit flours has rapidly advanced as a strategy to take advantage of its nutritional and technological benefits, which are strongly valued nowadays. Many times, raw exotic fruit is not consumed directly; some processing steps to isolate the product of interest from other constituents of the plant are usually necessary. In other cases, exotic fruits are used in food products like juices, jellies, and ice creams, and even by the cosmetics industry for the production of oils, moisturizers, and soaps. All these processes generate residues such as peels, seeds, pomace, and bran.14 Although fruit by-products are residues, it has already been observed that they may have a higher amount of elements of nutritional interest than the food product itself. For example, grape pomace was shown to present a higher antioxidant capacity than red wine.4 In addition, interesting technological properties have been highlighted for such residues because they are rich in DF, such as thickening, water binding, and gelling, advantageous properties that may be used for example in bakery products. Industrial utilization of exotic fruit by-products would not only contribute to new businesses, but it also would provide alternative uses, and consequently the appropriate disposal of large amounts of the wastes generated by the agricultural and food industries.16 A search of scientific databases can provide many examples of flours based on exotic fruits and their processing residues, under the name of “flour” (mostly) or “powder” (made of whole fruit, like flour). They are ac¸ai pulp17; acerola seeds18 and pomace18–20; bambangan peels21; baobab pulp22,23 and seeds22,24; breadfruit pulp25,26; partially defatted baru (a by-product of the extraction of baru oil)27; buriti endocarp28; camu-camu pulp, peels, and seeds29; chañar pulp30,31; durian seed32 and pulp33; wolf’s fruit34; goldenberry pomace35; jabuticaba/jaboticaba (peel, pomace, and whole fruit)36–39; jackfruit seed40; marolo pulp and carpels41; mistol skin, pulp, and seed42; passion fruit peel43–46; peach-palm pulp47; pedada48; and pequi peels.49,50 A summarized description of several exotic fruits is given next, and some of them are shown in Fig. 1. • Ac¸ai is a fruit from the Amazon and other regions of South and Central America. It is a round fruit, approximately 2 cm in diameter; and it is dark purple when ripe. This fruit has been shown to present different biological activities and health effects, such as anti-inflammatory, antioxidant, and anticancer properties in vitro. Ac¸ai is consumed in the form of smoothies, ice cream, juice, and soda, and also as a side dish to rice, cassava flour, and seafood.51 • Acerola (Malpighia emarginata DC. and Malpighia glabra L.), also known as Barbados cherry, is native to Central America and northern South America. It is a small fruit (1–4 cm in diameter) that presents a thin and delicate peel that changes from orange-red to dark reddish-purple when ripe. Acerola is rich in flavonoids, phenolic acids, and carotenoids. The fruit is consumed raw or used to make juices.51 • Bambangan (Mangifera pajang Kosterm.) is a fruit found in Malaysia, Brunei, and Indonesia. It is a large fruit, three times bigger than commercial mangoes (Mangifera indica L.). Consumption of this as fresh fruit is not popular due to its fibrous pulp; generally, the fruit is consumed in the form of juice.21 • Baobab (Adansonia digitata L.) is found in the drylands of sub-Saharan Africa. The fruit suspends singly on lengthy stalks with an ovoid, woody shell of 20–30 cm long, and up to 10 cm in diameter. The shell has multiple brownish and hard seeds, which are round or ovoid, imbed in a yellowish-white, acidic, and floury pulp. The naturally dry fruit pulp is rich in vitamin C, calcium, potassium, and DF.24,52 • Baru (Dipteryx alata Vogel) is commonly found in the Brazilian savanna (cerrado). It is a small fruit with an average length of around 5 cm, presenting a light brown general coloration; the mesocarp has a dry and fibrous pulp, and the endocarp protects one ellipsoid seed, the almond, that possesses high values of crude protein (more than 20%) and lipids (more than 30%). The pulp is consumed in the form of flour and sweets, and the toasted almond is used in typical Brazilian sweets, cakes, and liquors, and also for the extraction of oil composed primarily by unsaturated fatty acids (more than 70%).54

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FIG. 1 Several exotic tropical fruits: (A) acerola; (B) baru almonds; (C) passion fruit; (D) buriti; (E) buriti (debarking); (F) jaboticaba; (G) pequi; (H) pequi (cross-section); (I) jaboticabas (squeezed).

• Breadfruit [Artocarpus altilis (Parkinson ex F.A.Zorn) Fosberg] is a tropical fruit native to countries of the South Pacific and has been successfully introduced in West African countries. Breadfruit has a large amount of starch [more than 60% on a dry weight basis (dwb)], as well as significant amounts of some vitamins and minerals. It is a roundish fruit, 10–20 cm in diameter, its peel is greenish to brownish, and the pulp is green and white, somewhat fibrous.25,26,53 • Buriti (Mauritia flexuosa L. f.) is a fruit native to South America. It is a small fruit, with a reddish brown peel and yellow pulp. The pulp is used in the preparation of sweets, ice creams, juices, jams and wine, and is rich in carotenoids. Oil extracted from the pulp is used by the cosmetic industry.55 • Camu-camu (Myrciaria dubia (Kunth) McVaugh) is a native Amazonian fruit, consisting of round berries with an average diameter of 2.5 cm. The pulp is pink, and the peel is red-purple when ripe. Camu-camu is considered one of the best sources of vitamin C.29 • Chañar (Geoffroea decorticans (Hook and Arn.) Burkart) is a fruit native to South America (Peru, Bolivia, Paraguay, and Argentina). It is a reddish-brown drupe of approximately 1.0–1.7 cm in diameter, with a sweet and sticky pulp. Chañar is consumed in typical preparations such as añapa and arropes, with or without sugar.30 • Durian (Durio zibethinus L.) is a tropical fruit of Southeast Asia (Indonesia, Malaysia, Philippines, and Thailand). It is an oblong or round fruit whose peel is spiky, and its color varies from green to brown. The pulp is sweet and can be yellow, white, golden yellow, or red. The fruit has a unique taste and strong odor.32,56 • Goldenberry (Physalis peruviana L.) is a fruit from the Andes region, and it also grows in some Latin American and African countries. It is a small berry (4–10 g), of orange color, with many small seeds. The pulp contains high levels of vitamin C, carotenoids and minerals, and it is used for the production of juices, jams, raisins, and other products.35 • Jabuticaba or jaboticaba (Plinia cauliflora (Mart.) Kausel) is an endemic fruit from Brazil. It is a small fruit, 3 to 4 cm in diameter, and contains one to four seeds inside. Its peel is thin and colored very purple to black (rich in anthocyanins), and its pulp is white, sweet, and slightly acidic. The fruits are consumed fresh or in the form of juices, jams, and distilled liquors.36,37

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• Jackfruit (Artocarpus heterophyllus Lam.) is a popular fruit from India and Bangladesh. It is a very big fruit, 30–40 cm in length, oblong and cylindrical in shape, and it may weigh up to 45 kg. Its bark is thorny, and when ripe, the fruit contains well-flavored yellow sweet bulbs and seeds. Jackfruit is popular in many culinary preparations such as pickles, ice cream, candies, and other desserts, or it is dehydrated into thin, round papad.57,58 • Marolo (Annona crassiflora Mart.) is a fruit from the Brazilian savanna. It weighs 0.5–4.5 kg and inside, it contains 90–190 carpels, with one seed each. Its peel is thorny and green and the pulp is yellow, with characteristic scent and flavor. It is rich in B complex vitamins (thiamine and riboflavin), ascorbic acid, and carotenoids. Marolo is consumed fresh when ripe, in the form of juices, jams, and ice creams.41 • Mistol (Ziziphus mistol Griseb.) is grown in the Great American Chaco, in South America. The fruit is a reddishbrown round drupe, 1.0–1.7 cm in diameter. Its pulp is sticky and sweet, with exquisite taste. Mistol is a plant used in traditional medicine and consumed in typical food preparations such as bolanchao, a common snack that is prepared by milling the fruit until getting a grainy paste that is pressed into spheres that are coated with roasted algarrobo (Prosopis alba Griseb.) flour seed.42,59 • Passion fruit (Passiflora spp.), also known as maracujá, was discovered by European missionaries in South Am zerica. Among the exotic fruits discussed in this chapter, passion fruit is perhaps the most known, since its variety Passiflora edulis f. flavicarpa is marketed in different places. The fruit is round, 8–10 cm in diameter, and the peel is yellowish-green when ripe. It has many seeds, surrounded by a jelly yellow pulp with sweet-acid taste and intense aroma. Passiflora species are widely used in traditional medicine as sedatives and anxiolytics, and it is also exploited by the food industry for the production of juices and ice creams, in addition to the cosmetic and pharmaceutical industries.60 • Peach-palm fruit (Bactris gasipaes Kunth), also known as pupunha, was domesticated in Amazonia (i.e., South America and southern Central America) and already, in the pre-Columbian period, was consumed as a nutritional source of starch, oil, and beta carotene. It is a small fruit 30–70 g, fibrous red, with orange or yellow epicarp. The mesocarp is moist, starchy, and oily and the fruit presents a single endocarp with a white, fibrous, and oily endosperm.61 • Pedada (Sonneratia caseolaris (L.) Engl.) is a typical mangrove plant found in Indonesia, China, and Thailand. It is a round, flattened fruit with a smooth green peel, with a star-shaped structure at one end and a thin, long structure at the other end.62 • Pequi (Caryocar brasiliense A.St.-Hil.) is a fruit from the Brazilian savanna. It is a globular fruit, which contains a green external peel (exocarp) and a yellowish internal part of the peel (mesocarp). The pulp is yellow to orange and contains thorns embedded. The pulp is rich in phenolic compounds.50 • Wolf fruit (Solanum lycocarpum A. St.-Hil.; or fruta do lobo) is native to South America and is commonly found in the margins of Brazilian highways. It is a smooth and globular berry, 8–13 cm in diameter, with a fleshy pulp with many seeds. When ripe, the peel and pulp are yellow and the pulp is soft, sweetish and very aromatic, being used in preparation of sweets and jellies.34

PRODUCTION TECHNIQUES OF EXOTIC FRUIT FLOURS The production of flours from fruits and their by-products requires the reduction of the amount of free water and the transformation of the product into a powder. A review of recent articles that deal with exotic fruit flours reviewed six major techniques for reducing moisture: hot air drying (number of articles that used the technique, n ¼ 18), freeze drying (lyophilization) (n ¼ 10), spray drying (n ¼ 1), fixed bed drying (n ¼ 2), microwave vacuum drying (n ¼ 1), and sun drying (n ¼ 1). Some of the evaluated fruits did not require drying for the production of flour. This was the case with baobab because the fruit pulp already has low moisture and a floury aspect.23,24 Baru waste also did not require dehydration, given that the flour was produced from low moisture bran obtained after extracting the seed oil.27 Hot air drying was the most used technique for drying exotic fruits and their processing residues. Hot air drying is the most common and cheapest food dehydration process. It consists of exposing the material to a continuously flowing, hot stream of air, allowing the moisture to evaporate. Hot air drying provides dehydrated products that have a shelf life of approximately 1 year, but the technique may compromise the composition of bioactive compounds that are temperature sensitive.63 The majority of researchers cited the use of an oven with forced air circulation, although some did not discriminate whether or not forced air circulation was used. Some typical drying conditions were 45°C for 24 h for goldenberry35 and 72°C for 3 h for peach-palm.47 The majority of fruits and their residues were processed at 50°C (n ¼ 8); three samples were dried at 60°C (two samples of durian32,33 and one of pequi49); the buriti endocarp sample was dried at 65°C for 24 h28; and the marolo was dehydrated at 50°C for 20 h, followed by 70°C for 11 h until moisture

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fell below 10%. The option for lower temperatures is an alternative to minimize the decomposition of bioactive compounds. Freeze drying is the second most used technique in the production of flours based on exotic fruits and their residues. It is the best technique for preserving fresh product characteristics. It consists of dehydration by sublimation of a previously frozen feedstock. Low temperatures and the absence of liquid water interrupt most of the microbiological and deterioration reactions, resulting in a high-quality product. Maintenance of the shape and primary structure of the products, as well as minimal reduction of volume, are possible due to the solid state of water during freeze drying.63 Other advantages of this technique include avoiding protein denaturation, retaining volatile compounds accountable for flavor, easy rehydration, defined porous product structure, high yields, long shelf life, and the possibility of sterile and easy handling. However, freeze drying is very expensive due to its high energy consumption and high operation and maintenance costs; the energy required for freeze drying is almost twice the energy spent in conventional drying, and the cost is four to eight times higher.64 Elevated energy consumption and high financial costs must be considered in the feasibility analysis of processes that aim at the sustainable use of waste materials. Freeze drying was compared to hot air drying of marolo pulp and its carpels.41 After a blanching process (70°C for 5 min in hot water), the samples were dehydrated either by freeze drying (51°C and 250 Pa) or convective hot-air drying (50°C for 20 h, followed by 70°C for 11 h). The samples were milled after dehydration. The final moisture contents of the samples were similar for the two drying processes. Regarding proximate composition, the only parameter that presented significant differences was lipid content, which was higher for the samples produced by freeze drying. This was attributed to the higher porosity of freeze-dried products, allowing more effective solvent penetration during the extraction of lipids. A comparison of the pulp flours indicated that freeze-dried flour from marolo pulp presented higher insoluble fiber content, although no significant difference was observed for soluble DF. With the exception of the flour based on freeze-dried carpels of marolo, all the samples presented volume reduction in relation to the fresh product. This behavior was expected and did not occur for the referred sample due to reduction in the size of the granules during the milling process, which compromised the low shrinkage in the freeze-dried products. In relation to the solubility of the samples, there was a reduction in the solubility of the convective hot air-dried samples compared to the fresh samples, but this behavior was not observed for the samples that were freeze dried. The decrease in solubility can result from the interactions among nutrients due to high temperatures. As for the color, some browning was observed in the convective hot air-dried samples, and the coloring was lighter in the freeze-dried samples compared to the fresh marolo. According to the authors, triacylglycerol profile analysis suggests that the drying process has no significant effect on these compounds for marolo. In a recent freeze-drying study, Silva et al.65 evaluated the impact of technique on bioactive compounds of yellow passion fruit residues and compared samples frozen in the freezer and in liquid nitrogen. However, whether the samples were ground for the production of flours was not mentioned. Moisture removal during freeze drying was influenced by the freezing process because in the conventional freezing (slower), big and homogeneous ice crystals were formed, and in the cryogenic method (faster), the formed crystals were smaller and strongly attached to the internal structure of the samples. Evaluation of bioactive compounds indicated that the total phenolic content was higher in the samples previously frozen in the freezer, indicating a beneficial effect of a slow freezing method. The levels of citric acid decreased regardless of the technique, indicating degradation of this compound. The ascorbic acid content also decreased slightly. The levels of pectin were higher in the samples frozen in liquid nitrogen for 72 h, indicating that the longer freeze-drying process contributed better to conservation of this fiber. Therefore, the choice of method should be based on the desired objectives and the available resources. Among the exotic fruit flours surveyed, only camu-camu samples were dehydrated by spray drying.29 This technique consists of converting liquid feeds directly into powder in a single-step procedure.66 It is important to highlight that this process requires the sample to be liquid, which is characteristic only of the pulp of some fruits. Perhaps for this reason, few studies have reported the use of this technique. During spray drying, the sample goes through atomization, followed by drying of liquid droplets, and finally by powder recovery. The costs of spray drying are lower than those of freeze drying, and the drying takes place over short periods (5–100 s). However, the technique involves relatively high temperatures—often an inlet air temperature of 150–220°C and outlet air temperature of 50–80°C, which can degrade the most sensitive compounds and compromise color and flavor.66 Camu-camu sample was dried at an inlet temperature of 185°C and an outlet temperature of 95°C. Maltodextrin (10%) was added to decrease the stickiness of the powder. In the same study, a camu-camu sample including peels and seeds was dried in a fluidized bed dryer (45–55°C). The justification for the choice of techniques was the initial water content (90% for the pulp and 60% for the mixture of peels and seeds).29 However, it is not possible to compare both techniques due to the different natures of the products.

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Another type of dryer employed was a spouted bed using inert particles. Ac¸ai pulp was unfrozen and mixed with water; maltodextrin was added to assist in the formation of powder; the formed paste was passed through a colloid mill to reduce the suspended solids and avoid the incrustation of the spray nozzle; and the sample was then dried in a cone-cylindrical spouted bed. It was observed that yield and moisture increased as the temperature increased, and anthocyanins were more sensitive to the airflow rate. In the optimal drying condition, an energetic powder with low moisture, good flowability, a porous heterogeneous surface, and high anthocyanin content were obtained.17 Microwave vacuum drying was compared to hot air drying for preparing flours based on unripe and fully ripe durian. Hot air drying was performed at 60°C for 13 h (unripe durian) and 30 h (fully ripe durian), whereas the durian paste was dried in a microwave vacuum dryer at 5.49 W/g microwave power for 8 min (unripe durian) and 12 min (fully ripe durian). No significant differences were observed between the hot-air microwave vacuum drying in terms of proximate composition, thermal properties, or the X-ray diffraction (XRD) pattern. However, pasting properties (related to gelatinization and short-term retrogradation during heating and cooling) were better for microwave vacuum-dried samples, as well as the color parameters. The authors argued that the microwave heating interfered with the reassociation of amylopectin branch chains, and that durian flour produced by microwave vacuum can be useful for slowing the staling mechanism in bakery foods.33 Among the surveyed samples, only jackfruit seed flour was prepared by sun drying. The process took 3 days.40 Sun drying is not recommended for this purpose because the temperature is not homogeneous and there is no control of the desired temperature. There are also risks of contamination from air exposition. After dehydration, the samples are ground and then they are sifted to select the desired particle size of the flour. Spray-dried samples do not need to be ground. Different equipments were mentioned for the grinding steps, including mortar and pestle for pomace acerola19,20; centrifuge ball mill for bambangan peels21; hammer mill for baobab pulp and seeds,22 breadfruit pulp,26 and peach-palm pulp,47 passion fruit peel43,44; helix mill for chañar31; blender for partially defatted baru,27 jackfruit seed,40 and passion fruit peel46; ultracentrifugal mill for durian pulp33; grinder for goldenberry pomace35; knife mill for acerola seed and pomace18 and passion fruit peel45; and refrigerated multiuse mill for jaboticaba peel.39 The particle size ranged from 0.850 mm (20 mesh) for passion-fruit-peel flour43,44 to 0.149 mm (100 mesh) for durian pulp flour.33 In general, production of exotic fruit flours goes through the following steps: selection, washing, sanitizing and bleaching (both optional), separation of parts, dehydration, milling (except for spray and bed drying), and sifting. Sanitizing was described in some studies and was accomplished by immersion in a sodium hypochlorite solution in the case of buriti endocarp and jabuticaba peels,28 and by ultraviolet (UV) irradiation in the case of jackfruit seeds.40 In some cases, the samples may be comminuted with water prior to drying, in a process known as wet milling. Wet milling was used for producing pequi peel flours.50

FEATURES OF FLOURS BASED ON EXOTIC FRUITS AND THEIR PROCESSING RESIDUES Distinctive bioactive compounds are found in flours based on exotic fruits and their processing residues. Among the most cited are DFs, phenolic compounds, and carotenoids. The concept of DF has been widely discussed by the scientific community. The Codex Alimentarius Commission defines DF as carbohydrate polymers that are not hydrolyzed by human enzymes in the small intestine, and considers that DF derived from vegetable origin may include compounds associated with polysaccharides in the cell walls. With regard to the number of monomer units, a footnote has been added to the definition that allows national authorities to decide about the inclusion of carbohydrates from 3 to 9 monomeric units.67 Up to 2005, the official methods employed to analyze DF only quantify DF components with high-molecular-weight. The AOAC 985.29 method determines total DF, and AOAC 991.43 distinguishes insoluble and soluble fractions of those fibers. These methods do not quantify low-molecular-weight DF (such as fructooligosaccharides, galactooligosaccharides, inulin, and polydextrose) and measure only one of the four categories of RS. Methods AOAC 2009.01 and AOAC 2011.25 were developed to include low-molecular-weight DF.68 Insoluble and soluble DF content of flours based on processing residues of exotic are displayed in Table 1. Insoluble DF ranged from 6.5 (dehulled durian seed flour)32 to 75.66 g/100 g (acerola seed flour).18 Soluble DF ranged from 1.2 (dehulled durian seed flour)32 to 33.4 g/100 g (bambangan peels flour).21 A few recent studies evaluated the neutral sugar content of flours based on bambangan21 and pequi peels.50 The techniques employed were high-performance liquid chromatography (HPLC)21 and the acetate alditol method by gas chromatography (GC) with flame ionization detection.50 Mannose, arabinose, and glucose were the major

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TABLE 1 Insoluble and Soluble DF in Flours Based on Exotic Fruit Residues Flours

Insoluble DF (g/100 g)

Soluble DF (g/100 g)

Analytical method

Reference

Acerola pomace

28.58  1.24

8.74  0.53

AOAC 991.43a

Marques et al.18

Acerola seed

75.66  1.58

4.76  0.98

AOAC 991.43a

Marques et al.18

38.8  0.85

33.4  0.63

AOAC 991.43b

Hassan et al.21

Baru waste

33.73  2.43

5.07  1.31

AOAC 991.43a

Pinelli et al.27

Buriti endocarp

67.50  0.50

3.03  0.06

AOAC 991.43c

Becker et al.28

6.5  0.25

1.2  0.20

AOAC 991.43b

Amin and Arshad32

41.7  0.39

11.2  0.45

AOAC 991.43b

Amin and Arshad32

Jaboticaba peel

20.00  2.00

5.00  0.50

Asp et al. (1983)d

Lenquiste et al.36

Jaboticaba peel

6.53  0.97

Jaboticaba pomace Pequi peel (epicarp and mesocarp)

Bambangan peel

Durian seed (dehulled) Durian seed (whole)

Pequi peel (mesocarp only)

10.72  0.70

e

AOAC 991.43

Gurak et al.37

16.42  1.08

4.12  0.86

AOAC 991.43e

Gurak et al.37

33.94  1.43

9.38  0.93

Asp et al. (1983)d

Leão et al.50

30.3  0.46

9.5  2.40

Asp et al. (1983)d

Leão et al.50

a

The authors cite the enzymatic-gravimetric method of the Association of Official Analytical Chemists (AOAC). Official methods of analysis. 16th ed. Washington, DC: AOAC; 2005. The authors cite the enzymatic and gravimetric method described by Prosky L, Asp NG, Schweizer TF, De Vries JW, Furda, I. Determination of insoluble, soluble and total dietary fiber in foods and food products: Collaboration study. J Assoc Off Anal Chem 1998;71(5):1017–23. c The authors cite enzymatic-gravimetric method by AOAC. Official methods of analysis. 18th ed. Gaithersburg: AOAC; 2010. d Asp NG, Johansson CG, Hallmer H, Siljestr€ om M. Rapid enzymatic assay of insoluble and soluble dietary fiber. J Agric Food Chem 1983;31:476–82. e AOAC. Official methods of analysis. 18th ed. AOAC; 2006. b

monosaccharides found in soluble and insoluble fractions of bambangan-peel flour. According to the authors of one study, these monosaccharides may indicate the presence of arabinomannose, galactomannas, or other pectic monosaccharides. They also inferred that cellulose is the nonstarch polysaccharide present in flour.21 From the analysis of neutral monosaccharides and mid-infrared (IR) spectra of pequi peel flours, Leão and collaborators50 concluded that pectic polysaccharide of pequi-peel flours may consist mainly of rhamnogalacturonans, and the hemicellulose fraction is composed mainly of arabinogalactans, xylans, and glucomannans. Phenolics are a large class of bioactive compounds, being the secondary metabolites synthesized by vegetables. Phenolic acids, flavonoids, and tannins are the most commonly found phenolic compounds in the diet. Phenolic acids are divided into two groups: (1) hydroxybenzoic acids (C6–C1 structure), such as gallic and vanillic acids; and (2) hydroxycinnamic acids (C6–C3 structure), such as caffeic and ferulic acids. Flavonoids are the largest group of plant phenolics. They are low-molecular-weight compounds, with a C6–C3–C6 configuration. The configuration is in a structure of two aromatic rings joined by a 3-carbon bridge, commonly taking the form of a heterocyclic ring, which varies, resulting in different classes: flavonols (or catechins), flavones, flavanones, flavanonols, isoflavones, and anthocyanidins. Tannins are relatively high-molecular-weight compounds that are divided in hydrolysable (gallo- and ellagi-tannins) and condensed tannins or proanthocyanidins (polymers of polyhydroxyflavan-3-ol monomers). Phenolic compounds are known to exhibit antioxidant activity due to their ability to scavenge free radicals, give electron or hydrogen atoms, and chelate metal cations.69 Analysis of polyphenolics can evaluate total phenolic content or quantify a specific group or class or an individual phenolic. In all cases, the compounds are first extracted and then analyzed. The extraction can be done using such solvents as methanol, acetone, ethanol, ethyl acetate, water, and others. The choice depends on the chemical nature, extraction method, and particle size, among other variables. The quantification of phenolics can be done by spectrophotometric methods and chromatographic techniques, with or without mass spectrometric analysis. Total phenolic content is widely quantified by using Folin-Ciocalteu and Folin-Denis spectrophotometric methods.70 Phenolic compounds are found in greater amounts in plant peels and seeds, and in lower quantities in the pulp.14 The total phenolic content of some exotic fruits and their residues are compiled in Table 2. Among these results, the high levels found in the pequi-peel flours can be observed.

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FEATURES OF FLOURS BASED ON EXOTIC FRUITS AND THEIR PROCESSING RESIDUES

TABLE 2

Total Phenolic Compounds in Flours Based on Exotic Fruits and Their Processing Residues

Flours

Total phenolic compound

Analytical method

References

Acerola pomace

10.82  0.09 g 100 g–1 of dry matter

Folin–Denis

Marques et al.18

Acerola seed

4.73  0.07 g 100 g–1 of dry matter

Folin–Denis

Marques et al.18

Bambangan peel

98.3  0.12 mg GAE/g

Folin–Ciocalteu

Hassan et al.21

Baru waste

121.34  2.61 mg GAE/100 g

Folin–Ciocalteu

Pinelli et al.27

Chañar

277  3 mg GAE/100 g dry weight

Folin–Ciocalteu

Costamagna et al.30

Jaboticaba peel

30.24  1.37 mg GAE/g dry weight

Folin–Ciocalteu

Gurak et al.37

Jaboticaba pomace

43.39  4.45 mg GAE/g dry weight

Folin–Ciocalteu

Gurak et al.37

Mistol seed

425.2  6.0 mg GAE/100 g

Folin–Ciocalteu

Orqueda et al.42

Mistol pulp

356.0  5.1 mg GAE/100 g

Folin–Ciocalteu

Orqueda et al.42

Mistol skin

188.8  4.5 mg GAE/100 g

Folin–Ciocalteu

Orqueda et al.42

Pequi peel (epicarp and mesocarp)

17.42  0.53 g GAE/100 g

Folin–Ciocalteu

Leão et al.50

Pequi peel (mesocarp only)

15.49  0.43 g GAE/100 g

Folin–Ciocalteu

Leão et al.50

GAE, gallic acid equivalent.

A number of compounds were found in flours based on exotic fruits and their processing residues by chromatographic techniques. Using HPLC coupled with a mass spectrometer detector, Fracassetti et al.29 detected more than 30 phenolic compounds in camu-camu pulp, peel, and seed flours. The authors quantified flavonols, anthocyanins, ellagic acid derivatives, ellagitannins, proanthocyanidins, and gallic acid derivatives. Cazarin et al.44 identified eight flavonoids in passion-fruit-peel flour by ultra-performance liquid chromatography (UPLC) with mass spectrometry, with emphasis on isoorientin (C21H20O11) and vicenin (C27H30O15). Gallic acid, cathequin, epigallocatechin gallate, epicatechin, syringic acid, p-cumaric acid, and 7-quercetin were identified in acerola-bagasse flour by Marques et al.20 using HPLC. Condensed tannins (proanthocyanidins) usually are associated with polysaccharides of DF. Appreciable amounts of these compounds are not extracted by aqueous organic solvents. Perez-Jimenez et al.71 and Zurita et al.72 proposed methods for analyzing these compounds. The extraction residues with the aqueous organic solvents were reacted with HCl/butanol solution (containing FeCl3). In this chemical reaction, two products are formed: free anthocyanidins and xanthylium compounds. In the human organism, the condensed tannins associated with DF are not absorbed in the small intestine, and these compounds enter the large intestine, where they act as antioxidants.73 Leão et al.50 used the method described by Zurita et al.72 for evaluation of proanthocyanidins in pequi-peel flours. Significant amounts of nonextractable proanthocyanidins were detected—346.84 mg/100 g in epicarp- and mesocarp-pequi flours, and 215.54 mg/100 g in mesocarp-pequi flours. Carotenoids are a class of isoprenoid pigments synthesized by photosynthetic organisms. These compounds can be divided into carotenes (which contain only a hydrocarbon chain, without any functional group) and xanthophylls (which contain oxygen as a functional group). Carotenoids presented antioxidant, photoprotection, and provitamin A activities. For the chemical analyses of carotenoids, the compounds are extracted with organic solvents (such as acetone, hexane, chloroform, diethyl ether, methanol, isopropanol, and methylene chloride) and then examined by spectrophotometric and chromatographic methods.74 Carotenoids are primarily found on the surface of the tissues, such as external pericarp and peels.14 Costamagna et al.30 and Leão et al.50 quantified total carotenoids by a spectrophotometric method in chañar flour and pequi-peel flour, respectively. The authors found 0.12  0.04 mg of β-carotene equivalents per 100 g in chañar flour; 3.499 mg/100 g carotenoids in epicarp- and mesocarp-based pequi flours, and 2.116 mg/100 g carotenoids in mesocarp-based pequi flours. Rojas-Garbanzo et al.47 identified and quantified carotenoids present in the production of peach-palm fruit flour by HPLC. The researchers detected 13 carotenoids in flour, including carotenes and lycopene. Flour production reduced the total carotenoid levels, presenting a final retention rate of 63.7% by the end of the process. Pro-vitamin A value was also reduced during the process. However, the carotenoid content found in the peach-palm fruit flour remained very significant.

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TECHNOLOGICAL PROPERTIES AND APPLICATIONS IN FOOD As previously discussed, flours based on exotic fruits and their processing residues may have technological properties that would be of interest to the food industry. Foschia et al.16 highlighted that the use of fruit by-products may confer benefits such as thickening, gelling, and water binding, so these properties can be exploited in products such as baked goods. The use of these flours in food also improves their nutritional composition because they are rich in DF and antioxidant compounds. Becker et al.28 incorporated buriti-hendocarp flour in whole wheat gluten-free cookies. A mixture of brown-rice flour (70%) and cornstarch (30%) was replaced by buriti-endocarp flour at four levels (5%, 10%, 15%, and 20%). Cookies without buriti-endocarp flour were used as a control. All cookies with buriti-endocarp flour had higher contents of DF, were darker and harder, had smaller diameter, and presented smaller spread ratios compared to the control cookies. Cookies with up to 15% buriti-endocarp flour were well accepted by tasters. The authors commented that the buriti-endocarp flour could be used for gluten-free whole cookies production. Pineli et al.27 produced cookies with replacement of wheat flour by defatted baru flour, with four levels (25, 50, 75, and 100 g/100 g) of replacement. Cookies with 100 g/100 g of wheat flour were used as the control. The other ingredients were salt, butter, sugar, eggs, and baking powder. Cookies with partially defatted baru flour had a higher content of bioactive compounds than cookies made with wheat flour alone, indicating the contribution of baru residue to flour increased the antioxidant potential. The cookie with partial replacement (50 g/100 g) showed increases of 48% in the level of total phenolics, 5.6-fold the level of total flavonoids, and 4.4-fold the content of tannin. As for texture, the cookies with substitutions of up to 50 g/100 g of wheat flour by baru-residue flour showed no difference in hardness and fracturability compared to the control sample. Replacements of higher amounts of baru flour caused gradual increase in these parameters, however. The authors attributed the influence on texture to the higher content of protein and DF in cookies with baru-residue flour. However, only cookies with partial substitution of 25 g/100 g were considered to be acceptable with respect to taste and texture sensory attributes when compared to the control sample. The authors argued that the reception could be improved if consumers were informed about the potential health improvements (“source of fiber” or “food with high content of antioxidants”), but this was not investigated in this specific study. Jabuticaba-peel powder was used by Oliveira et al.39 in the production of extruded breakfast cereal with 90% corn flour and 10% corn flour over 80% whole-grain wheat flour. Jabuticaba peel increased sectional expansion and decreased bulk density in corn-flour samples. Color and overall impression were improved by the addition of jabuticaba peel. Breadfruit flour was used to produce biscuits with replacement of wheat flour in ratios of wheat:breadfruit flours of 67:33, 50:50, 33:67, and 0:100. Biscuits without breadfruit flour were set as control samples. More water was used as the proportion of breadfruit flour increased. The others ingredients were fat, sugar, skim powdered milk, salt, and sodium bicarbonate. With increasing levels of substitution of breadfruit flour, moisture and DF content increased and protein and total ash content decreased. Fat and carbohydrate content did not change significantly. The sensory analysis showed that the hedonic scores of the biscuits employing breadfruit flour were usually high, except when they were 100% breadfruit. There were no significant differences in the attributes of crispness, flavor, and overall preference among the biscuits made from 100% and 67% wheat flours, but the 100% breadfruit-flour biscuit was ranked the worst by the tasters.25 Technological properties are important to evaluate the possible applications of flours in food products. Appiah et al.26 assessed the effect of fermentation on the technological properties of breadfruit-pulp flour. Breadfruit samples were spontaneously fermented under ambient conditions in distilled water, and after fermentation, they were dried, milled, and sieved. Unfermented flour was prepared under the same conditions for comparison. Fermentation improved technological properties such as bulk density, gelation concentration, and peak viscosity. Coelho et al.46 evaluated the technological properties of passion-fruit-peel flour and compared them to those of commercially available additives (low- and high-methoxyl pectins, carrageenan, guar gum, and xanthan gum). Two flours were produced; the first (treated passion-fruit-peel flour) underwent a preprocessing step (i.e., maceration in water for 12 h) before dehydration, whereas the second did not undergo preprocessing. The authors observed that passion-fruit-peel flour showed similar emulsifying potential as xanthan and guar gums, which are commonly added to mayonnaise. They also presented significant stabilizing capacity because they hindered particle settling in nectars. Passion-fruit-residue flour still presented good thickening and good gelling in structured fruit and ice cream toppings. Among the flours, treated passion-fruit-peel flour showed higher values of stabilizing, gelling,

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POTENTIAL APPLICATIONS TO HEALTH AND DISEASE PREVENTION: IN VITRO, EXPERIMENTAL, AND CLINICAL STUDIES

397

and thickening powers. Therefore, it was concluded that the passion-fruit flours can be used to replace the commercial hydrocolloids investigated. It was also highlighted that passion-fruit flours can be obtained at a low cost and through simple procedures. The studies previously discussed in this chapter show that exotic fruit flours can be added in food preparations, aggregating their technological properties and/or improving nutritional composition. Sensory attributes could present some changes, depending on the flour amount replaced, and this factor should be taken into account.

POTENTIAL APPLICATIONS TO HEALTH AND DISEASE PREVENTION: IN VITRO, EXPERIMENTAL, AND CLINICAL STUDIES Bioactive compounds present in exotic fruit flours and their residues have shown potential uses in health and disease prevention. In vitro assays have indicated that these products present antioxidant activity21,29,50 and the ability to inhibit enzymes related to metabolic syndromes.19,31,42 Studies with animals demonstrate that these flours are effective in controlling the symptoms of chronic diseases.36,76 Finally, clinical trials show similar results in humans as well.23,38,45 Different antioxidants compounds present in the exotic fruit flours and their residues may act to defend the organism from oxidative damage. Excess reactive oxygen species (ROS) may induce severe cell damage, causing lipid and protein oxidation and deoxyribonucleic acid (DNA) modification.75 In vitro chemical assays such as 2,2diphenyl-1-picryhydrazyl free radical (DPPH), ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), and 2,20 -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) are used to measure the antioxidant activity of phytochemicals. Hassan et al.21 used the DPPH assay to analyze bambangan-peel flour, and the result, expressed as IC50, was 44.5  0.24 μg/mL, considered high by researchers. Fracassetti et al.29 also evaluated the antioxidant activity of camu-camu flours by DPPH, ABTS, and ORAC assays, and the authors observed that the residue (i.e., peel and seed) flour presented better results than the dry pulp. Peels are expected to have a higher amount of antioxidants because they protect the fruits against external aggressive agents such as bacteria and insects. Leão et al.50 evaluated antioxidant activity of pequi-peel flour by DPPH, ABTS, and FRAP assays, and the pequi mesocarp plus epicarp flour showed higher antioxidant capacity than flour made of only pequi mesocarp. These results were expected because it is known that the outermost parts of the fruits have many antioxidant compounds to protect the fruits against external aggressive agents. Inhibition of enzymes responsible for processing dietary carbohydrates and lipids is interesting for its application for the prevention and treatment of excess weight. On the other hand, the inhibition of enzymes involved in protein digestion, such as trypsin, has a malefic effect because it impairs the complete amino acid absorption in food products. Thus, flours made from exotic fruit and their residue were investigated for their ability to inhibit digestive enzymes. Marques et al.19 tested the inhibition potential of acerola-pomace flour with respect to α-amylase, α-glucosidase, lipase, and trypsin, both before and after exposure to simulated gastric fluid. Significant inhibition of α-amylase and α-glucosidase was reported, but not of lipase. The authors highlighted that the inhibition of enzymes of carbohydrate metabolism contribute to the prevention and treatment of obesity. Also, α-amylase digests carbohydrates, elevating glycemic levels after a meal. High glycemic levels are associated with the development of type 2 diabetes. Inhibition of α-glucosidase contributes to satiety and weight loss because it slows gastric emptying. However, the acerola pomace flour also inhibited the enzyme trypsin, and such behavior can be considered an antinutritional factor. The presence of trypsin inhibitors in the diet may lead to a reduction in growth rate in animals, decrease in protein digestibility, and weight loss. However, such inhibition was reduced by 63% in the presence of simulated gastric fluid. The authors attribute the inhibition of digestive enzymes to phenolic compounds present in the flour that are capable of forming soluble complexes with proteins like digestive enzymes, because they can inactivate them. Polyphenolic extract of chañar flour was able to inhibit α-amylase, α-glucosidase, lipase, and HMG-CoA reductase. The extracts were treated with digestive enzymes in order to simulate the effect of gastroduodenal digestion. The extract was still active for α-amylase after treatment, but its potency was lower than the undigested extract. Inhibition of lipase and α-glucosidase was not affected by digestion. Furthermore, results with α-glucosidase were better than with the reference compound acarbose, whose continuous use may cause several adverse effects. Inhibition of lipase and HMG-CoA reductase can contribute to the decrease of cholesterol and triglycerides in the blood by lipid digestion

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30. CHARACTERIZATION AND APPLICATION OF EXOTIC FRUIT FLOURS

and absorption, and also by inhibiting cholesterol biosynthesis.31 Slightly smaller inhibition results of α-glucosidase and lipase enzymes were found for mistol pulp and residue flours.42 Experimental studies have also shown effect of flours based on exotic fruits in the control of chronic diseases. Lenquiste et al.36 evaluated the effects of freeze-dried jaboticaba peel added to a high-fat (HF) diet in obese rats. Animals that were fed an HF diet with 1%, 2%, and 4% of freeze-dried jaboticaba peel added presented a reduction in hyperinsulinemia, reversing the development of insulin resistance. Freeze-dried jaboticaba peel at 2% increased serum levels of high-density lipoprotein (HDL) cholesterol, which is an important cardioprotector. But the freeze-dried jaboticaba peel showed no effect on weight loss or improvement in body composition. Improvement of insulin sensitivity was also reported in a clinical study with freeze-dried jaboticaba peel.38 In this study, adults with normal body mass index (BMI) received 27.6 g of jaboticaba peel powder (1.25 g of total phenolics) during breakfast with 50 g of potentially available starch. The individuals also had lunch 3 h later, with food containing the same amount of starch, but without jaboticaba peel powder. The intervention group was compared with a control group. Insulin levels were significantly decreased 240 min after consumption of the breakfast with jaboticaba peel. The authors attribute the effect to the capacity of phenolic compounds to inhibit digestive enzymes and two glucose transporters in the intestine (SGLT1 and GLUT2), which decreases glucose absorption and the postprandial response. The researchers also recall the role of DFs. Once associated with DF, phenolic compounds are slowly released into the intestine, which may explain the results even after the second meal. This effect associated with the consumption of jaboticaba peel powder indicates that there is potential for prevention of insulin resistance and diabetes. Passion-fruit-peel flour also improved insulin sensitivity in obese rats fed an HF diet.76 The animals consumed an HF diet for 4 weeks to induce metabolic conditions related to obesity. Afterward, one group consumed the HF diet with 2.5% (w/w) of passion-fruit-peel flour added for another 6 weeks. The researchers observed that passion-fruit-peel flour significantly increased the constant rate of glucose disappearance, which would suggest a protective effect against insulin resistance induced by a HF diet in rats. Passion-fruit-peel flour also contributed to counteract the body weight gain caused by the HF diet. The authors noted that passion-fruit-peel-flour consumption increased gene expression for cocaine and amphetamine-regulated transcript expression (CART), showing that the passion-fruit-peel flour enhance satiety in rats fed an HF diet. The proinflammatory cytokines IL-6, TNF-α, and MCP-1 were significantly higher for the control group than the passion-fruit-peel-flour group, indicating that this type of flour may attenuate obesity-related inflammation in rats. The researchers attributed the observed effects to the synergic action of polyphenols and DFs present in the passion-fruit-peel flour, although further studies are needed to elucidate this hypothesis.76 In another clinical study with passion-fruit-peel flour, Marques et al.45 observed improvement in plasma concentrations of cholesterol (total, LDL, and HDL) in human immunodeficiency virus (HIV) patients with lipodystrophy syndrome secondary to antiretroviral therapy who received 30 g of passion-fruit-peel flour for 90 days in addition to diet therapy. Gadour et al.23 also observed effects on total cholesterol and triglyceride levels in hyperlipidemic patients who consumed baobab powder. The study compared a control group (n ¼ 134) that received atorvastatin only with an intervention group (n ¼ 136) that received atorvastatin daily plus 30 mg of baobab powder for 28 days. The authors attributed the results to DF presented in the baobab powder, arguing that the DFs bonded to bile acids, decreasing absorption in the terminal ileum. The fermentation of the fibers in the large intestine produced short chain fatty acids, decreasing the pH, and also decreasing the absorption of bile acids, leading to its excretion. To produce new bile acids, cholesterol had to be mobilized, thus reducing its levels.23 Passion-fruit-peel flour was also tested in the dextran sodium sulfate model of mouse colitis. Mice were treated with passion-fruit-peel flour (8 mg/mL in the drinking water) for 2 weeks, and then, for 5 days, the mice received dextran sodium sulfate in the drinking water (3%) to induce colitis. Passion-fruit-peel flour consumption presented an intestinal antiinflammatory effect and attenuated the colonic damage, according to the reduced disease activity index values and histological evaluation. Proinflammatory cytokine expression decreased, and there was an increase in the intestinal protective barrier and the formation of short chain fatty acids.44 Despite the potential applications to health and disease prevention, it is necessary to evaluate the safety and other nutritional aspects of the prepared flours. For example, the inhibition of enzymes involved in protein digestion can be harmful. Silva et al.43 observed lower levels of albumin and total protein in rats fed a diet containing passion-fruit-peel flour (50% of the cellulose content replaced with flour). The total serum albumin values were within the normal range for rodents, but total serum proteins were a little below the desired levels. More studies are needed to verify this effect because other research has not reported the same condition. Same researchers tested techniques to reduce the antinutritional factors in flours based on exotic fruit and their residues. Nnan and Obiakor24 observed that the fermentation of baobab seeds decreased tannin and phytate content. Siqueira et al.49 evaluated the effect of soaking on the nutritional quality of pequi peel flour. They reported reduction

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REFERENCES

399

of phenols, tannins, and protein digestibility, as well as elimination of trypsin inhibitors. However, there was an increase in starch digestibility, which may not be interesting, as well as the abovementioned reduction of phenolic compounds. Phenolic compounds are sometimes referred to as antinutritional factors, especially tannins, and sometimes defended as antioxidant compounds. The circumstances, the necessity, as well as the dosage and concomitance of intake with other foods, should always be evaluated for an appropriate classification. With regard to toxic compounds, Jariyah et al.77 evaluated ethanol extract from pedada-fruit flour and did not find any alkaloids. No mouse died up to 168 h after consuming 21.00 g/kg in a single oral dose of ethanol extract. Pedada fruit flour was thus placed in the categories of “Nontoxic” and “Safe” for food products. However, studies are still needed on other types of flours.

PROSPECTS FOR FUTURE RESEARCH Studies of flours based on exotic fruits and their processing residues have been increasing in recent years. However, there is a need for further research investigating the safety of consuming the most diverse of these flours, especially those prepared from fruit processing by-products or wastes. As these are raw materials that are not widely consumed, or in most cases not consumed by humans, little is known about their effects on human health. The composition of these flours must be further explored as well, in order to provide a better knowledge of their constituents and to identify which compounds are involved in the physiological effects observed with their ingestion. Dose response curves should be investigated too. In addition, it is necessary to evaluate the interaction of the compounds of these flours with other components of the diet or the ingredients of the food products to which the flours are added.

CONCLUDING REMARKS Flours based on exotic fruits and their processing residues may be a good strategy for the regular supply of important sources of DF and antioxidant compounds. These flours can be added to foods and contribute to health promotion and prevention of chronic diseases.

SUMMARY POINTS • Exotic fruit pulp and residues can be used for flour production. • For the production of flour, these fruits and their residues need to be dried in a manner that minimizes the loss of antioxidant compounds. • DFs, phenolic compounds, and carotenoids are the main bioactive compounds described in these flours. • Flours based on exotic fruits and their processing residues can be added to various food preparations. • Bioactive compounds present in these flours can contribute towards health promotion and prevention of chronic diseases.

References 1. Liu R. Health benefits of fruit and vegetables are from additive and synergistic combinations of phytochemicals. Am J Clin Nutr 2003;78:517S–520S. 2. Anonymous. Position of the American dietetic association: health implications of dietary Fiber. J Am Diet Assoc 2008;108:1716–31. 3. Veronese N, Solmi M, Caruso M, Giannelli G, Osella A, Evangelou E, Maggi S, Fontana L, Stubbs B, Tzoulaki I. Dietary fiber and health outcomes: an umbrella review of systematic reviews and meta-analyses. Am J Clin Nutr 2018;107:436–44. 4. Saura-Calixto F. Antioxidant dietary fiber product: a new concept and a potential food ingredient. J Agric Food Chem 1998;46:4303–6. 5. Agama-Acevedo E, Islas-Hernandez J, Pacheco-Vargas G, Osorio-Diaz P, Bello-Perez L. Starch digestibility and glycemic index of cookies partially substituted with unripe banana flour. LWT-Food Sci Technol 2012;46:177–82. 6. Sardá F, de Lima F, Lopes N, Santos A, Tobaruela E, Kato E, Menezes E. Identification of carbohydrate parameters in commercial unripe banana flour. Food Res Int 2016;81:203–9. 7. Casarotti S, Penna A. Acidification profile, probiotic in vitro gastrointestinal tolerance and viability in fermented milk with fruit flours. Int Dairy J 2015;41(1-6). 8. O’Shea N, Ktenioudaki A, Smyth T, McLoughlin P, Doran L, Auty M, Arendt E, Gallagher E. Physicochemical assessment of two fruit by-products as functional ingredients: apple and orange pomace. J Food Eng 2015;153:89–95.

3. FORTIFICATION OF FLOURS AND BREADS

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30. CHARACTERIZATION AND APPLICATION OF EXOTIC FRUIT FLOURS

9. Urquiaga I, D’Acuna S, Perez D, Dicenta S, Echeverria G, Rigotti A, Leighton F. Wine grape pomace flour improves blood pressure, fasting glucose and protein damage in humans: a randomized controlled trial. Biol Res 2015;48:49. 10. O’Shea N, Arendt E, Gallagher E. State of the art in gluten-free research. J Food Sci 2014;79:R1067–76. 11. Brasil-Ag^encia Nacional deVigil^ancia Sanitária. Regulamento tecnico para produtos de cereais, amidos, farinhas e farelos; 2005. Resoluc¸ão RDC no. 263, de 22 de setembro de 2005, Diário Oficial da União, 23 de setembro de 2005, Sec¸ão 1, p. 368 (in Portuguese). 12. Fernandes F, Rodrigues S, Law C, Mujumdar A. Drying of exotic tropical fruits: a comprehensive review. Food Bioproc Tech 2011;4:163–85. 13. Rufino M, Alves R, de Brito E, Perez-Jimenez J, Saura-Calixto F, Mancini J. Bioactive compounds and antioxidant capacities of 18 non-traditional tropical fruits from Brazil. Food Chem 2010;121:996–1002. 14. Ayala-Zavala J, Vega-Vega V, Rosas-Dominguez C, Palafox-Carlos H, Villa-Rodriguez J, Siddiqui M, Davila-Avina J, Gonzalez-Aguilar G. Agroindustrial potential of exotic fruit byproducts as a source of food additives. Food Res Int 2011;44:1866–74. 15. Hettinger N. Exotic species, naturalisation, and biological nativism. Environ Values 2001;10:193–224. 16. Foschia M, Peressini D, Sensidoni A, Brennan C. The effects of dietary fibre addition on the quality of common cereal products. J Cereal Sci 2013;58:216–27. 17. Costa R, Andreola K, Mattietto R, de Faria L, Taranto O. Effect of operating conditions on the yield and quality of acai (Euterpe oleracea Mart.) powder produced in spouted bed. LWT-Food Sci Technol 2015;64:1196–203. 18. Marques T, Correa A, Lino J, de Abreu C, Simao A. Chemical constituents and technological functional properties of acerola (Malpighia emarginata DC.) waste flour. Food Sci Technol 2013;33:526–31. 19. Marques T, Caetano A, Simao A, Castro F, Ramos V, Correa A. Metanolic extract of Malpighia emarginata bagasse: phenolic compounds and inhibitory potential on digestive enzymes. Braz J Pharmac 2016;26:191–6. 20. Marques T, Caetano A, Rodrigues L, Simao A, Machado G, Correa A. Characterization of phenolic compounds, antioxidant and antibacterial potential the extract of acerola bagasse flour. Acta Sci Technol 2017;39:143–8. 21. Hassan F, Ismail A, Hamid A, Azlan A, Al-sheraji S. Characterisation of fibre-rich powder and antioxidant capacity of Mangifera pajang K. fruit peels. Food Chem 2011;126:283–8. 22. Osman M. Chemical and nutrient analysis of baobab (Adansonia digitata) fruit and seed protein solubility. Plant Foods Hum Nutr 2004;59:29–33. 23. Gadour M, Khidir H, Adam I, Gasim G. Effects of a powder of the fruit of Adansonia digitata (Tabaldia, Gongolase, or baobab tree) on serum lipids. J Herbal Med 2017;8:14–6. 24. Nnam N, Obiakor P. Effect of fermentation on the nutrient and antinutrient composition of baobab (Adansonia digitata) seeds and rice (Oryza sativa) grains. Ecol Food Nutr 2003;42:265–77. 25. Omobuwajo TO. Compositional characteristics and sensory quality of biscuits, prawn crackers and fried chips produced from beadfruit. Innov Food Sci Emerg Technol 2003;4(2):219–25. 26. Appiah F, Oduro I, Ellis W. Functional properties of Artocarpus altilis pulp flour as affected by fermentation. Agric Biol J North Am 2011;2:7. 27. Pineli L, de Carvalho M, de Aguiar L, de Oliveira G, Celestino S, Botelho R, Chiarello M. Use of baru (Brazilian almond) waste from physical extraction of oil to produce flour and cookies. LWT-Food Sci Technol 2015;60:50–5. 28. Becker F, Damiani C, de Melo A, Borges P, Boas E. Incorporation of Buriti endocarp flour in gluten-free whole cookies as potential source of dietary Fiber. Plant Foods Hum Nutr 2014;69:344–50. 29. Fracassetti D, Costa C, Moulay L, Tomas-Barberan F. Ellagic acid derivatives, ellagitannins, proanthocyanidins and other phenolics, vitamin C and antioxidant capacity of two powder products from camu-camu fruit (Myrciaria dubia). Food Chem 2013;139:578–88. 30. Costamagna M, Ordonez R, Zampini I, Sayago J, Isla M. Nutritional and antioxidant properties of Geoffroea decorticans, an Argentinean fruit, and derived products (flour, arrope, decoction and hydroalcoholic beverage). Food Res Int 2013;54:160–8. 31. Costamagna MS, Zampini IC, Alberto MR, Cuello S, Torres S, Perez J, Quispe C, Schmeda-Hirschmann G, Isla MI. Polyphenols rich fraction from Geoffroea decorticans fruits flour affects key enzymes involved in metabolic syndrome, oxidative stress and inflammatory process. Food Chem 2016;190:392–402. 32. Amin A, Arshad R. Proximate composition and pasting properties of durian (Durio zibethinus) seed flour. Int J Postharvest Technol Innov 2009;1:9. 33. Bai-Ngew S, Therdthai N, Dhamvithee P, Zhou W. A study of the effect of the drying process on the composition and physicochemical properties of flours obtained from durian fruits of two ripening stages. Int J Food Sci Technol 2014;49:230–7. 34. Clerici M, Kallmann C, Gaspi F, Morgano M, Martinez-Bustos F, Chang Y. Physical, chemical and technological characteristics of Solanum lycocarpum A. St.—HILL (Solanaceae) fruit flour and starch. Food Res Int 2011;44:2143–50. 35. Mokhtar S, Swailam H, Embaby H. Physicochemical properties, nutritional value and techno-functional properties of goldenberry (Physalis peruviana) waste powder concise title: Composition of goldenberry juice waste. Food Chem 2018;248:1–7. 36. Lenquiste S, Batista A, Marineli R, Dragano N, Marostica M. Freeze-dried Jaboticaba peel added to high-fat diet increases HDL-cholesterol and improves insulin resistance in obese rats. Food Res Int 2012;49:153–60. 37. Gurak P, De Bona G, Tessaro I, Marczak L. Jaboticaba Pomace powder obtained as a co-product of juice extraction: a comparative study of powder obtained from Peel and whole fruit. Food Res Int 2014;62:786–92. 38. Plaza M, Batista A, Cazarin C, Sandahl M, Turner C, Ostman E, Marstica M. Characterization of antioxidant polyphenols from Myrciaria Jaboticaba peel and their effects on glucose metabolism and antioxidant status: a pilot clinical study. Food Chem 2016;211:185–97. 39. Oliveira L, Alencar N, Steel C. Improvement of sensorial and technological characteristics of extruded breakfast cereals enriched with whole grain wheat flour and jabuticaba (Myrciaria cauliflora) peel. LWT-Food Sci Technol 2018;90:207–14. 40. Jayus, Setiawan D, Giyarto, Fleischmann P, Kim K, Hwang S. Physical and chemical characteristics of jackfruit (Artocarpus heterophyllus Lamk.) seeds flour produced under fermentation process by lactobacillus plantarum. In: International Conference on Food, Agriculture and Natural Resources, Ic-Fanres 2015 Agric Agric Sci Procedia. 9; 2016. p. 342–7. 41. Correa S, Clerici M, Garcia J, Ferreira E, Eberlin M, Azevedo L. Evaluation of dehydrated marolo (Annona crassiflora) flour and carpels by freezedrying and convective hot-air drying. Food Res Int 2011;44:2385–90. 42. Orqueda M, Zampini I, Torres S, Alberto M, Ramos L, Schmeda-Hirschmann G, Isla M. Chemical and functional characterization of skin, pulp and seed powder from the argentine native fruit mistol (Ziziphus mistol). Effects of phenolic fractions on key enzymes involved in metabolic syndrome and oxidative stress. J Funct Foods 2017;37:531–40. 43. da Silva J, Cazarin C, Batista A, Marostica M. Effects of passion fruit (Passiflora edulis) byproduct intake in antioxidant status of Wistar rats tissues. LWT-Food Sci Technol 2014;59:1213–9.

3. FORTIFICATION OF FLOURS AND BREADS

REFERENCES

401

44. Cazarin C, Rodriguez-Nogales A, Algieri F, Utrilla M, Rodriguez-Cabezas M, Garrido-Mesa J, Guerra-Hernandez E, Braga P, Reyes F, Marostica M, Galvez J. Intestinal anti-inflammatory effects of Passiflora edulis peel in the dextran sodium sulphate model of mouse colitis. J Funct Foods 2016;26:565–76. 45. Marques S, Tibonati R, Sabaa-Srur A, Luo R, Shejwalkar P, Hara K, Dobbs T, Smith R. Evaluation of the effects of passion fruit peel flour (Passilfora edulis fo. Flavicarpa) on metabolic changes in HIV patients with lipodystrophy syndrome secondary to antiretroviral therapy. Braz J Pharmac 2016;26:420–6. 46. Coelho E, Gomes R, Machado B, Oliveira R, Lima M, de Azevedo L, Guez M. Passion fruit peel flour—technological properties and application in food products. Food Hydrocoll 2017;62:158–64. 47. Rojas-Garbanzo C, Perez A, Bustos-Carmona J, Vaillant F. Identification and quantification of carotenoids by HPLC-DAD during the process of peach palm (Bactris gasipaes HBK) flour. Food Res Int 2011;44:2377–84. 48. Jariyah J, Widjanarko S, Yunianta, Estiasih T, Fleischmann P, Kim K, Hwang S. Quality evaluation of wheat-Pedada fruit flour (PFF) biscuit with different emulsifiers. In: International Conference on Food, Agriculture and Natural Resources, Ic-Fanres 2015 Agriculture and Agricultural Science Procedia. 9; 2016. p. 518–24. 49. Siqueira B, Soares M, Fernandes K, Caliari M, Damiani C. Effect of soaking on the nutritional quality of pequi (Caryocar brasiliense Camb.) peel flour. Food Sci Technol 2013;33:500–6. 50. Leao D, Franca A, Oliveira L, Bastos R, Coimbra M. Physicochemical characterization, antioxidant capacity, total phenolic and proanthocyanidin content of flours prepared from pequi (Caryocar brasilense Camb.) fruit by-products. Food Chem 2017;225:146–53. 51. Elisa Schreckinger M, Lotton J, Lila M, Mejia E. Berries from South America: a comprehensive review on chemistry, health potential, and commercialization. J Med Food 2010;13:233–46. 52. Muthai K, Karori M, Muchugi A, Indieka A, Dembele C, Mng’omba S, Jamnadass R. Nutritional variation in baobab (Adansonia digitata L.) fruit pulp and seeds based on Africa geographical regions. Food Sci Nutr 2017;5:1116–29. 53. Encyclopædia Britannica, Inc. https://www.britannica.com. 54. Vera R, Souza E. Baru. Rev Bras Frutic 2009;31:101–295. 55. Sampaio MB, Carrazza LR. Araújo R, editor. Manual Tecnológico de Aproveitamento Integral do Fruto e da Folha do Buriti (Mauritia flexuosa). Brazil: Instituto Sociedade, Populac¸ão e Natureza (ISPN); 2012. p. 76. 56. Ho L, Bhat R. Exploring the potential nutraceutical values of durian (Durio zibethinus L.)—an exotic tropical fruit. Food Chem 2015;168:80–9. 57. Baliga MS, Shivashankara AR, Haniadka R, Dsouza J, Bhat HP. Phytochemistry, nutritional and pharmacological properties of Artocarpus heterophyllus Lam (jackfruit): a review. Food Res Int 2011;44:1800–11. 58. Moorthy I, Maran J, Ilakya S, Anitha S, Sabarima S, Priya B. Ultrasound assisted extraction of pectin from waste Artocarpus heterophyllus fruit peel. Ultrason Sonochem 2017;34:525–30. 59. Cardozo ML, Ordoñez RM, Alberto MR, Zampini IC, Isla MI. Antioxidant and anti-inflammatory activity characterization and genotoxicity evaluation of Ziziphus mistol ripe berries, exotic Argentinean fruit. Food Res Int 2011;44:2063–71. 60. Correa R, Peralta R, Haminiuk C, Maciel G, Bracht A, Ferreira I. The past decade findings related with nutritional composition, bioactive molecules and biotechnological applications of Passiflora spp. (passion fruit). Trends Food Sci Technol 2016;58:79–95. 61. Clement CR, Weber JC, van Leeuwen J, Astorga Domian C, Cole DM, Arevalo Lopez LA, Arg€ uello H. Why extensive research and development did not promote use of peach palm fruit in Latin America. Agr Syst 2004;61:195–206. 62. Tropicos. http://www.tropicos.org. [Accessed April 2018]. 63. Ratti C. Hot air and freeze-drying of high-value foods: a review. J Food Eng 2001;49:311–9. 64. Ciurzy nska A, Lenart A. Freeze-drying—application in food processing and biotechnology—a review. Pol J Food Nutr Sci 2011;61:165–71. https://doi.org/10.2478/v10222-011-0017-5. 65. Silva N, Santana R, Duarte C, Barrozo M. Impact of freeze-drying on bioactive compounds of yellow passion fruit residues. J Food Process Eng 2017;40:e12514. 66. Shishir MRI, Chen W. Trends of spray drying: a critical review on drying of fruit and vegetable juices. Trends Food Sci Technol 2017;65:49–67. 67. Codex Alimentarius. Guidelines on nutrition labelling CAC/GL 2-1985 as last revision in 2015. Rome: Joint FAO/WHO, Codex Alimentarius International Food Standards, FAO; 2015. 68. Macagnan FT, da Silva LP, Hecktheuer LH. Dietary fibre: the scientific search for an ideal definition and methodology of analysis, and its physiological importance as a carrier of bioactive compounds. Food Res Int 2016;85:144–54. 69. Balasundram N, Sundram K, Samman S. Phenolic compounds in plants and Agri-industrial by-products: antioxidant activity, occurrence, and potential uses. Food Chem 2006;99:191–203. 70. Naczk M, Shahidi F. Extraction and analysis of phenolics in food. J Chromatogr A 2004;1054:95–111. 71. Perez-Jimenez J, Torres J. Analysis of nonextractable phenolic compounds in foods: the current state of the art. J Agric Food Chem 2011;59:12713–24. 72. Zurita J, Diaz-Rubio M, Saura-Calixto F. Improved procedure to determine non-extractable polymeric proanthocyanidins in plant foods. Int J Food Sci Nutr 2012;63:936–9. 73. Saura-Calixto F. Dietary fiber as a carrier of dietary antioxidants: an essential physiological function. J Agric Food Chem 2011;59:43–9. 74. Saini RK, Keum Y-S. Carotenoid extraction methods: a review of recent developments. Food Chem 2018;240:90–103. 75. Meng D, Zhang P, Zhang L, Wang H, Ho C-T, Li S, Shahidi F, Zhao H. Detection of cellular redox reactions and antioxidant activity assays. J Funct Foods 2017;37:467–79. 76. Lima G, Vuolo M, Batista A, Dragano N, Solon C, Marostica M. Passiflora edulis peel intake improves insulin sensitivity, increasing incretins and hypothalamic satietogenic neuropeptide in rats on a high-fat diet. Nutrition 2016;32:863–70. 77. Jariyah J, Widjanarko S, Yunianta Y, Estiasih T. Phytochemical and acute toxicity studies of ethanol extract fromPedada (Sonneratia caseolaris) fruit flour (PFF). Int J Ad Sci Eng Inf Technol 2015;5:4.

3. FORTIFICATION OF FLOURS AND BREADS