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Slowly digestible cookies prepared from resistant starch-rich lintnerized banana starch
ARTICLE IN PRESS JOURNAL OF FOOD COMPOSITION AND ANALYSIS Journal of Food Composition and Analysis 20 (2007) 175–181 www.elsevier.com/locate/jfca
Original Article
Slowly digestible cookies prepared from resistant starch-rich lintnerized banana starch Alejandro Aparicio-Saguila´na, Sonia G. Sa´yago-Ayerdib, Apolonio Vargas-Torresa, Juscelino Tovarc, Tania E. Ascencio-Oterob, Luis A. Bello-Pe´reza, a
Centro de Desarrollo de Productos Bio´ticos del IPN, Km 8.5 carr. Yautepec-Jojutla, colonia San Isidro, apartado postal 24, 62731 Yautepec, Morelos, Me´xico b Instituto Tecnolo´gico de Acapulco, Calzada Instituto Tecnolo´gico S/N Crucero Cayaco-Puerto Marque´s, 39905 Acapulco, Guerrero, Me´xico c Instituto de Biologı´a Experimental, Facultad de Ciencias, Universidad Central de Venezuela, Apartado Postal 47069, Caracas 1041A, Venezuela Received 10 May 2005; received in revised form 15 July 2006; accepted 17 July 2006
Abstract Experimental cookies were formulated with a resistant starch-rich powder (RSRP) prepared from autoclave-treated lintnerized banana starch. The products were studied regarding chemical composition, available starch (AS), resistant starch (RS) and rate of starch digestion in vitro. In order to evaluate the acceptance of RSRP-products, a first affective test was carried out on four cookie formulations containing different RSRP levels. The formulation chosen corresponded to a wheat flour:RRSP ratio of 15:85. Chemical composition of the cookies showed no difference in ash and lipid contents between control (100% wheat flour) and RSRP-cookies (Po0.05). RSRPcookies had higher AS and RS levels than control cookies, from the addition of RSRP. The hydrolysis index (HI)-based predicted glycemic index for the RSRP-cookies was 60.53, which was significantly lower than for control samples (77.62), suggesting a ‘‘slow carbohydrate’’ feature for the RSRP-based goods. The second affective test indicated similar preference for RSRP-containing cookies and control samples. Results reveal RSRP from banana starch as a potential ingredient for bakery products containing slowly digestible carbohydrates. r 2006 Elsevier Inc. All rights reserved. Keywords: Starch; Banana; Bakery product; Affective test; Resistant starch; Starch digestibility; Lintnerized starch; Slow food; Slow carbohydrate
1. Introduction The development of new products is a strategic area of the food industry. Consumers are demanding foods that show two main properties: the first-one deals with the traditional nutritional aspects of the food, whereas, as a second feature, additional health benefits are expected from its regular ingestion. These kinds of food products are often called nutraceutical foods. In a rapidly changing world, with altered food habits and stressful life styles, it is more and more recognized that a healthy digestive system is essential for the overall quality of life (Brouns et al., 2002). Corresponding author. Tel.: +52 735 3942020; fax: +5273941896.
E-mail address: [email protected] (L.A. Bello-Pe´rez). 0889-1575/$ - see front matter r 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.jfca.2006.07.005
One of the current tendencies in nutrition and health is to consume low-carbohydrate food products. In the 1980s, dietary fiber was identified as an important component of a healthy diet, and the food industry looked for palatable ways to increase the fiber content of their products. The first commercially available product to provide a concentrated source of RS was reported in the mid 1990s. Nowadays, a number of industries prepare RS-rich powders using a technology developed by Prof. Paul Seib’s group, at Kansas State University (Shin et al., 2003). The patent covers a special type of modification applied to any starch derived from cereal grains, roots, tubers and legumes, such as wheat, corn, oat, rice, potato, tapioca and mung (Vigna radiata L.) bean. However, it should be kept in mind that the starch source may play an important role in the nutritional and functional properties of RS
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products. In this sense, the nutritional/nutraceutical potential of banana starch has been claimed by several authors (Englyst et al., 1992; Pacheco-Delahaye et al., 2004). Resistant starches are not digested in the human small intestine and are fermented by bacterial microflora in the large bowel, affecting a number of physiological functions and thus having different effects on health, e.g., reduction of the glycemic and insulinemic responses to food, hypocholesterolemic action and protective effects against colorectal cancer (Asp et al., 1996). In recent years, there has been a considerable interest in the possibility of improving control of diabetic patients by altering the glycemic impact of the carbohydrates ingested. A tool for ranking foods with respect to how they potentially raise blood glucose is the glycemic index (GI) concept (Jenkins et al., 1981), which leads to the preferred selection of ‘‘slow carbohydrate’’ food items/diets (Jenkins et al., 1981; Bjo¨rck et al., 1994). Although it cannot be regarded as a general rule, a nutritional variable that may be linked to low GI properties is the RS content of a food or complete meal (Truswell, 1992). Various RS types have been characterized in common foods. According to Englyst et al. (1992), these indigestible starch fractions may be classified according both to the nature of the starch and its environment in the food. Thus, RS1 corresponds to physically inaccessible starches, entrapped in a cellular matrix, as in cooked legume seeds, and RS2 are native uncooked granules of some starches, such as those in raw potatoes and green bananas, whose crystallinity makes them scarcely susceptible to hydrolysis. RS3, on the other hand, consists mainly of retrograded starch fractions, which may be formed in cooked foods that are kept at low or room temperature. More recently, a fourth type (RS4), has been associated to certain fractions of chemically modified starches (Tovar et al., 1999; Laurentı´ n et al., 2003). Resistant starch can be found in both processed and raw food materials. From the four RS types, RS3 seems to be particularly interesting because it retains its indigestibility when added as an ingredient to processed foods. RS3 is produced by a combination of the gelatinization process, which is a disruption of the granular structure by heating starch with an excess of water (Farhat et al., 2001); and retrogradation, a slow recrystalization of starch components (amylose and amylopectin) upon cooling or dehydration (Shamai et al., 2003). As it was mentioned before, modern food manufacturing methods destroy most forms of resistant starch, making them unsuitable as ingredients in highly processed food systems. This fact gives importance to the production of RS-rich powders that may be used in the formulation of diverse products. Potential applications for such a type of ingredient include breads, tortillas, pizza crust, cookies, muffins, waffles, breakfast cereals, snack products and nutritional bars, as well as lowfat fermented milks, ultra-heat treatment (UHT) flavored milk drinks, and ready-to-use powdered mixes, such as
instant soups and chocolate drinks. In a recent study, a resistant starch-rich powder (RSRP) was prepared from lintnerized banana starch, which retains its amylolysis resistant features after subsequent heat treatment (Aparicio-Saguila´n et al., 2005). Lintnerized starch is obtained by mild acid hydrolysis of both a-1,4 and a-1,6 glycosidic linkages of amylose and amylopectin, preferentially in the amorphous regions of granules (amylose and branched regions of amylopectin). Such a treatment leaves starch preparations with increased crystalline contents, which results in augmented resistance to enzymatic hydrolysis. The objective of this study was to evaluate starch digestibility and the in vitro predicted GI of cookies prepared with banana RSRP preparation. 2. Materials and methods 2.1. Banana starch isolation Banana starch was isolated using a previously described procedure (Flores-Gorosquera et al., 2004). Unripe (green) cooking bananas were purchased at the local market in Cuautla (Mexico); they were peeled, cut into 5–6 cm3 (100 kg total wt), immediately rinsed in citric acid solution (0.5 g/L) and then macerated at low speed in a Waring blender (10 kg fruit:10 L of solution) for 2 min. The homogenate was consecutively sieved through screens (20, 40, 100 and 200 US mesh) and washed with distilled water; it was then centrifuged in a semi-continuous Veronesi centrifuge (BSGAR 1500, Verona, Italy) at 10,750 rpm. The sediments from 100 and 200 US mesh were further purified by washing and additional centrifugation under the above-mentioned conditions. The white-starch sediments were dried in a spray dryer (Niro Atomizer, Model P-6.3, Copenhagen, Denmark), with a feeding temperature of 130–150 1C, a solid concentration in the feeding line of 30–40%, and an outlet temperature of 70–80 1C. The powder was ground to pass a US No. 100 sieve and stored at room temperature (25 1C) in a glass container. 2.2. Preparation of resistant starch-rich powder (RSRP) The RSRP was prepared as described by AparicioSaguila´n et al. (2005) from lintnerized banana starch. Lintner-modified starch (60 g) was mixed with 210 mL of water, and the mixture was pressure-cooked at 121 1C for 1 h in an autoclave. The mixture was cooled to room temperature and stored at 4 1C for 24 h. After three repetitions of the autoclaving and cooling cycles, the sample was freeze-dried and ground into fine particles (100 mesh US). 2.3. Preparation of cookies For the preparation of the cookies, raw materials were acquired in local supermarkets and stored in glass/plastic
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containers at room temperature (25 1C), or under refrigeration depending on the stored requirements of the material (Aparicio-Saguila´n et al., 2005). The formulation used for the cookies is shown in Table 1. In all cases, the products contained either wheat flour (control) (Gamesa, S.A. de C.V., Me´xico) or the wheat flour/RSRP mix. Margarine (containing a blend of vegetable oils, whey milk, soy lecithin, citric acid, etc.) was creamed, mixed with confectioner’s sugar and a whole egg, added to the wheat flour or the wheat flour/RSRP blend and mixed thoroughly; dough was rolled out to a 2 cm height on flat surface. Cookies were cut with a circular mold (6 cm diameter) and placed on greased aluminum cookie sheets. The cookies were baked in a household oven (Hotpoint, 6B4411LO, Leisser S.A. de C.V., San Luis Potosi, Me´xico), at an approximate temperature of 200 1C for 20 min. Once baked, cookies were allowed to cool down during 30 min and stored in a plastic container with hermetic cover. 2.4. Affective test on cookies with RSRP This test was applied to cookies prepared with different RSRP levels, with the purpose of choosing a suitable formulation for the next studies. Fifty non-trained students (35 females and 15 males, ages 18–23 years) chosen at random from Instituto Tecnolo´gico de Acapulco, took part in the trial, using a preference scale (4 ¼ like much, 3 ¼ like, 2 ¼ dislike, 1 ¼ dislike much). The cookies (2–3 g) were tested at random and identified with random numbers (Pedrero and Pangborn, 1989). When analysis showed significant differences (Po0.05), results were analyzed using a Friedman repeated measures analysis of variance on ranks procedure. Means were compared using Tukey’s tests. Statistical analyses were run using the computer SPSS V. 6.0 software (SPSS Institute Inc., Cary, NC). Once the proper cookie formulation was chosen, a second affective test (paired test) was carried out for comparing control and RSRP-cookie formulations. One hundred randomly chosen consumers (68 females and 32 males, age between 18 and 25 years) expressed their preference between both cookie formulations. The cookies (2–3 g) were tested at random and identified with random
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numbers (Pedrero and Pangborn, 1989). Statistical analysis was realized with Student t-test (Po0.05) using the SPSS program. 2.5. Chemical composition Moisture content was determined by gravimetric heating (13072 1C for 2 h) using a 2–3 g sample. Ash, protein and fat were analyzed according to AACC methods 08–01, 46–13, and 30–25, respectively (American Association of Cereal Chemists: Approved Methods of the AACC, 2000). 2.6. Digestibility tests Potentially available starch content was assessed following the multi-enzymatic protocol of Holm et al. (1986). The sample (300 mg db) was suspended in 20 mL of distilled water and incubated with a-amylase (Termamyls novo A/ S. Copenhagen) in a boiling water bath for 20 min. This mixture was then diluted to 100 mL with distilled water. In total, 0.5 mL of this suspension were mixed with amyloglucosidase (Boehringer, Mannheim, Germany) and 1.0 mL 0.1 mol/L Na acetate buffer, pH 4.75 was added. This mixture was incubated for 30 min at 60 1C. It was then diluted to 10 mL with distilled water and analyzed for glucose using the glucose oxidase peroxidase assay (SERAPAK Plus, Bayer de Me´xico, S.A. de C.V., Me´xico). Resistant starch was assessed by the method of Gon˜i et al. (1996), to estimate the total amount of indigestible starch (comprising RS2 and RS3 fractions). The method consists of the removal of protein with pepsin (P-7012, Sigma Chemical CO, St. Louis, MO) at 40 1C, 1 h pH 1.5, incubation with amylase (A-3176, Sigma Chemical CO, St. Louis, MO) at 37 1C for 16 h to hydrolyze digestible starch, treatment of the precipitate with 2 M KOH, incubation with amyloglucosidase (A-7255, Sigma Chemical CO, St. Louis, MO) at 60 1C, 45 min, pH 4.75 and determination of glucose using the glucose oxidase peroxidase assay (SERAPAK Plus, Bayer de Me´xico, S.A. de C.V, Me´xico). Soluble (SIF) and insoluble (IIF) indigestible fractions (IIFs) were assessed using the sequential pepsin/amylase hydrolysis method of Saura-Calixto et al. (2000); after the enzymatic treatments the sample was centrifuged and the residue
Table 1 Formulation of cookies with diverse resistant starch-rich powder (RSRP)* levels Ingredient (g)
Regular margarine Wheat flour RSRP Granulated sugar Whole egg *RSRP ¼ resistant starch-rich powder.
Control
22.5 44.9 0 15.7 16.8
Wheat flour:RSRP 35:65
25:75
15:85
10:90
22.5 15.7 29.2 15.7 16.8
22.5 11.2 33.7 15.7 16.8
22.5 6.7 38.2 15.7 16.8
22.5 4.5 40.4 15.7 16.8
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dried for gravimetric determination of the IIF. In order to calculate the SIF content, the supernatant was dialyzed and hydrolyzed with sulfuric acid for the assessment of reducing carbohydrate, using dinitrosalicilic acid. This method has been proposed as an alternative to enzymatic dietary fiber assays, aiming to include most of the physiologically indigestible part of foods, regardless of their chemical nature. The dietary fiber analysis measures non-*starch polysaccharides and lignin, whereas the IIF method also includes RS, indigestible protein, oligosaccharides, certain polyphenolic compounds, etc., that are not quantified in conventional DF tests. Starch hydrolysis index (HI) of products ‘‘as eaten’’ (chewing/dialysis test) was assessed with the protocol developed by Granfeldt et al. (1992). Samples of cookies containing 1 g of available starch were tested. Six healthy subjects (4 females and 2 males, ages between 20 and 22 years) participated in the chewing phase of the experiments, which was followed by pepsin digestion (P-7012, Sigma Chemical CO, St. Louis, MO) and incubation with porcine pancreatic amylase (A-6255, Sigma Chemical CO, St. Louis, MO) in a dialysis bag. The reducing amylolysis products appearing in the dialysate were measured colorimetrically, and expressed as maltose equivalents. Data were plotted as ‘‘hydrolysis degree’’ vs. ‘‘time’’ curves and the HI was calculated as the area under the curve (0–180 min) for the test product, expressed as a percentage of the corresponding area for a white bread reference sample, chewed by the same person. 2.7. Statistical analysis Results were expressed by means of values7standard error of three separate determinations. Comparison of means was performed by one-way analysis of variance (ANOVA) followed by Tukey’s test. The average HI was calculated from six digestion replicates runs for each sample and means were compared by the Wilcoxon matched-pair signed-rank test, each person being his own control. The predicted glycemic index (pGI) was calculated from HI values, using the empiric formula proposed by Granfeldt (1994): pGI ¼ 0.862 HI+8.198, for which the reported correlation coefficient (r) is 0.026 (Po0.00001). Statistical analyzes were run using the computer SPSS V. 6.0 software (SPSS Institute Inc., Cary, NC).
3. Results and discussion 3.1. Affective tests at cookies According to previous data, the banana RSRP preparation exhibits a resistant starch content of 19.34% (Aparicio-Saguila´n et al., 2005). Here, it was mixed with wheat flour in different proportions for cookie baking. The first affective test was carried out in order to choose the better taste formulation. Such a formulation was later evaluated in terms of chemical composition, starch digestibility, pGI and compared to a control wheat flour cookie by means of a second affective test. The statistical analysis of the first affective test (Table 2) showed that cookies prepared with the 35:65 and 15:85 (wheat flour:RSRP) proportions were preferred, with qualifications between 2.5 and 3.0 (Po0.05), although cookies prepared with the 35:65 and 25:75 ratios were accepted similarly. Therefore, the formulation with the highest RSRP level (15:85) was selected for further evaluation. The second affective test (Table 2) showed no difference in preference between the RSRP-cookie and control sample. Hence, besides its potential nutritional features, the RSRP-cookie has organoleptic acceptance by consumers. 3.2. Chemical composition The moisture content of the RSRP-cookie (5.70%) was slightly higher compared with the control sample (Table 3). This difference may be attributed to the particular formulation of each cookie, a fact that can be related to the relative abundance of amorphous starch zones in each material, which influences water absorption to a large extent (Slade and Levine, 1991). In a previous study from this group, a similar cookie type was prepared adding native corn or banana starches to wheat flour (Bello-Pe´rez et al., 2004), showing moisture levels that resemble those recorded here (4–5%). No difference (Po0.05) in fat content (12.55% and 12.69%) was detected between cookies (Table 3), which is in accordance with the equivalent margarine level used in both formulations. Similarly, the incorporation of RSRP did not produce a noticeable change in the final cookie ash content, reflecting the low mineral level in this ingredient
Table 2 Affective tests indices for cookies with diverse resistant starch-rich powder (RSRP*) levels** Test
First affective test: ANOVA on ranks Second affective test: t-student
Wheat flour:RSRP 35:65
25:75
15:85
10:90
2.5a,b
2.0b Wheat flour control 7.8270.45a
3.0a Wheat flour: RSRP (15:85) 6.9670.36a
1.0c
*RSRP ¼ resistant starch-rich powder. **Means in a row not sharing the same letter are significantly different (Po0.05).
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Sample Moisture Ash$ Protein$,& Lipid$ Available starch$ Resistant starch$ Insoluble indigestible fraction Soluble indigestible fraction Total indigestible fraction
Control cookie a
4.4970.34 0.3770.1a 11.970.40a 12.670.36a 37.270.40a 1.4870.05a 13.471.50a 3.4070.19a 16.870.92a
RSRP-cookie 5.7070.23b 0.4970.1a 5.0970.21b 12.770.01a 40.170.63b 8.4270.30b 20.571.04b 2.9270.13b 23.470.73b
*RSRP ¼ resistant starch-rich powder. **Dry matter basis. Values are means of three replicates7standard error. Means in row not sharing the same letter are significantly different (Po0.05). # RSRP:wheat flour ¼ 15:85. $ dry basis. & N 5.85.
(0.15%, Aparicio-Saguila´n et al., 2005). Although protein content (Table 3) in the control cookie (11.93%) was higher than in RSRP-containing sample (5.09%), this type of product is generally characterized by low protein contents and, evidently, the actual level depends on the formulation employed. Cookies formulated with banana and corn starches showed protein content between 6.18 and 9.2, respectively (Bello-Pe´rez et al., 2004). Other authors have reported protein content around 8–9% in cookies with grape skin added (Cannet-Romero et al., 2004). Potentially available starch in the RSRP-cookie was higher than in the control cookie (Table 3), although the difference is moderate (40% vs. 37%, respectively). Thus, RSRP appears to be a richer starch source (80% available starch content, Aparicio-Saguila´n et al., 2005) than wheat flour. Nonetheless, it should be mentioned that potentially AS is determined after fine grinding and boiling of the sample (Holm et al., 1988) and it therefore reports the sum of starch fractions that are readily available to enzymatic hydrolysis, plus RS1 and RS2 (Tovar and Velasco, 1995). Since the latter portions are not available for absorption in vivo (Englyst et al., 1992; Gon˜i et al., 1996), AS values in the RSRP-containing cookies may be larger than their actual digestible carbohydrate content. 3.3. Digestibility tests As expected, RS content in RSRP-cookies (8.42%) was markedly higher than in the control cookie (1.48%). These values indicate that RSRP contributes significantly to the final cookie RS content and confirm that the baking process does not alter this indigestible component. A˚kerberg et al. (1998) reported a 10.3% RS value in experimental bread; however, baking conditions in that study were chosen to produce no degradation of RS and to maximize its production due to the retrogradation
phenomenon. The use of native banana starch in cookie formulation resulted in up to 4.9% RS values (Bello-Pe´rez et al., 2004). The IIF was assessed as an alternative analysis for dietary fiber content (Saura-Calixto et al., 2000). The insoluble IIF for the control cookie was of 13.37% as compared to a 3.40% soluble indigestible fraction (SIF) level (Table 3). In the case of RSRP-cookie, the IIF was notably higher (20.5%), whereas only a slight difference in SIF was found between both cookies. The difference determined in total indigestible fraction (TIF) is in agreement with the different RS contents determined in these two products. Therefore, it can be concluded that the RSRP-cookie has considerable indigestible carbohydrate content. Enzymatic starch digestion curves for the different products are depicted in Fig. 1 and corresponding hydrolysis parameters are summarized in Table 4. White bread, used as reference, showed a digestion value of about 50% after 180 min, which agrees with the values reported in the original protocol by Granfeldt et al. (1992). Hydrolysis was markedly slow for RSRP-cookie and faster for the control cookie. Although the control-cookie and white bread showed similar hydrolysis rates until 90 min, the digestion velocity decreased for the control cookie thereafter, leading to a calculated HI of only 80.54. The low and slow hydrolysis of starch in the RSRP-cookie (60.71 HI) is noteworthy, since the digestion experiment was performed at equivalent AS levels. Thus, the presence of RS in this product seems to affect the susceptibility to digestion of the available starch portions. A similar situation was observed by Granfeldt et al. (1995) for high amylose arepas (corn bread). A HI of 73 was determined in barley bread (A˚kerberg et al., 1998), which is not too different from that of RSRP-cookie (Table 4), showing that glucose liberation from starch is lower in these samples than in white bread. This pattern is important in the mechanisms governing post-prandial glycemia for wheat flour based-products
60 50 Hydrolysis (%)
Table 3 Chemical composition of cookies with diverse resistant starch-rich powder (RSRP*) levels (%)**,#
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40 30 20 10 0 0
50
100
150
200
Time (min) Fig. 1. Average hydrolysis curves of: RSRP*-cookie (’), control cookie (m), white bread used as reference (E).
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Table 4 Hydrolysis index (HI) and predicted glycemic index (pGI) of cookies with diverse resistant starch-rich powder levels (RSRP*)**,& Sample
HI*
pGI#
Control cookie RSRP-cookie White bread reference
80.5472.64a 60.7172.28b 100c
77.62 60.53 94
*RSRP ¼ resistant starch-rich powder. **Hydrolysis index (HI) was related to bread ¼ 100 (Granfeldt et al., 1992). Values are mean of six chewing and dialysis replicates7standard error (Po0.05). & RSRP:wheat flour ¼ 15:85. # Predicted glucemic index (pIG) ¼ 0.862 HI+8.198 (Granfeldt, 1994). Means in columns not sharing the same letter are significantly different (Po0.05).
(Giacco et al., 2001) and foods with high RS content (Bjo¨rck and Liljeberg-Elmsta˚hl, 2003). The predicted GI value for the RSRP-sample (60.53) was below that determined in the control cookie (77.62). Predicted GI (Table 4) suggests important ‘‘slow digestion’’ features for the RSRP-cookie, which is in line with perceived health-beneficial characteristics of RS (Asp et al., 1996; Champ et al., 2003). The pGI value determined in RSRP-cookie suggests that this product has a low in vivo GI. Higher pGI values were determined in two barley breads containing different amylose/amylopectin ratio (A˚kerberg et al., 1998). Also, a GI value of 81 has been reported for energy bars (Foster-Powell et al., 2002), which is quite a bit higher than that recorded here for the RSRPcookie. In addition to the intrinsic properties of starch in the RSRP, the possible influence of the product compactness on the observed HI and pGI values cannot be ruled out. This might result in a slower diffusion of in vivo amylolytic products to the absorptive mucosa, as it has been demonstrated for other types of products (Bjo¨rck et al., 1994; Jenkins et al., 1987). The combined action of these factors results in moderate glycemic responses.
4. Conclusions A bakery product showing moderate available starch and slow release carbohydrate features was prepared using a resistant starch-rich powder (RSRP) from banana starch. The use of nutraceutical ingredients, such as RSRPs, may be useful in the development of new products for population sectors with reduced caloric and glycemic requirements.
Acknowledgments We appreciate the economic support from CGPI-IPN, COSNET-Me´xico, COFAA-IPN, EDI-IPN and LANFOODS.
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ARTICLE IN PRESS A. Aparicio-Saguila´n et al. / Journal of Food Composition and Analysis 20 (2007) 175–181 Holm, J., Lundquist, I., Bjorck, I., Eliasson, A.C., Asp, N.G., 1988. Degree of starch gelatinization, digestion rate of starch in vitro, and metabolic response in rats. American Journal of Clinical Nutrition 47, 1010–1016. Jenkins, D.J.A., Wolever, T.M.S., Collier, G.R., Ocana, A., Rao, A.V., Buckley, G., Lam, Y., Mayer, A., Thompson, L.U., 1987. Metabolic effects of a low-glycemic-index diet. American Journal of Clinical Nutrition 46, 968–975. Jenkins, D.J.A., Wolever, T.M.S., Taylor, R.H., Barker, H., Fielder, H., Baldwin, J.M., Bowling, A.C., Newman, H.C., Jenkins, A.L., Goff, D.V., 1981. Glycemic index of foods: a physiological basis for carbohydrates exchange. American Journal of Clinical Nutrition 34, 362–366. Laurentı´ n, A., Ca´rdenas, M., Ruales, J., Pe´rez, E., Tovar, J., 2003. Preparation of indigestible pyrodextrins from different starch sources. Journal of Agricultural and Food Chemistry 51, 5510–5515. Pacheco-Delahaye, E., Pe´rez, R., Schnell, M., 2004. Nutritional and sensory evaluation of powder drinks based on papaya, green plantain and rice bran. Glycemic index. Interciencia 29, 46–51. Pedrero, D., Pangborn, R.M., 1989. Evaluacio´n Sensorial de los Alimentos. Alhambra Editores, Me´xico, D.F., 75pp.
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Saura-Calixto, F., Garcı´ a-Alonso, A., Gon˜i, I., Bravo, L., 2000. In vitro determination of the indigestible fraction in foods: an alternative to dietary fiber analysis. Journal of Agricultural and Food Chemistry 48, 3334–3342. Shamai, K., Bianco-Peled, H., Simo´n, E., 2003. Polymorphism of resistant starch type III. Carbohydrate Polymers 54, 363–369. Shin, M., Woo, K., Seib, P., 2003. Hot-water solubility and water sorption of resistant starches at 25 1C. Cereal Chemistry 80, 564–566. Slade, L., Levine, H., 1991. Beyond water activity. Recent advances based on an alternative approach to the assessment of food quality and safety. Critical Review of Food Science and Nutrition 30, 115–360. Tovar, J., Velasco, Z., 1995. Available and resistant starch content in some Venezuelan foods. Acta Cientifica Venezolana 45, 208–209. Tovar, J., Herrera, E., Laurentı´ n, A., Melito, C., Pe´rez., E., 1999. In vitro digestibility of modified starches. In: Pandalai, S.G. (Ed.), Recent Research Advances in Agricultural and Food Chemistry, vol. 3. Research Signpost, Trivandrum, pp. 1–10. Truswell, A.S., 1992. Glycaemic index of foods. European Journal of Clinical Nutrition 46 (S1), S91–S101.
Original Article
Slowly digestible cookies prepared from resistant starch-rich lintnerized banana starch Alejandro Aparicio-Saguila´na, Sonia G. Sa´yago-Ayerdib, Apolonio Vargas-Torresa, Juscelino Tovarc, Tania E. Ascencio-Oterob, Luis A. Bello-Pe´reza, a
Centro de Desarrollo de Productos Bio´ticos del IPN, Km 8.5 carr. Yautepec-Jojutla, colonia San Isidro, apartado postal 24, 62731 Yautepec, Morelos, Me´xico b Instituto Tecnolo´gico de Acapulco, Calzada Instituto Tecnolo´gico S/N Crucero Cayaco-Puerto Marque´s, 39905 Acapulco, Guerrero, Me´xico c Instituto de Biologı´a Experimental, Facultad de Ciencias, Universidad Central de Venezuela, Apartado Postal 47069, Caracas 1041A, Venezuela Received 10 May 2005; received in revised form 15 July 2006; accepted 17 July 2006
Abstract Experimental cookies were formulated with a resistant starch-rich powder (RSRP) prepared from autoclave-treated lintnerized banana starch. The products were studied regarding chemical composition, available starch (AS), resistant starch (RS) and rate of starch digestion in vitro. In order to evaluate the acceptance of RSRP-products, a first affective test was carried out on four cookie formulations containing different RSRP levels. The formulation chosen corresponded to a wheat flour:RRSP ratio of 15:85. Chemical composition of the cookies showed no difference in ash and lipid contents between control (100% wheat flour) and RSRP-cookies (Po0.05). RSRPcookies had higher AS and RS levels than control cookies, from the addition of RSRP. The hydrolysis index (HI)-based predicted glycemic index for the RSRP-cookies was 60.53, which was significantly lower than for control samples (77.62), suggesting a ‘‘slow carbohydrate’’ feature for the RSRP-based goods. The second affective test indicated similar preference for RSRP-containing cookies and control samples. Results reveal RSRP from banana starch as a potential ingredient for bakery products containing slowly digestible carbohydrates. r 2006 Elsevier Inc. All rights reserved. Keywords: Starch; Banana; Bakery product; Affective test; Resistant starch; Starch digestibility; Lintnerized starch; Slow food; Slow carbohydrate
1. Introduction The development of new products is a strategic area of the food industry. Consumers are demanding foods that show two main properties: the first-one deals with the traditional nutritional aspects of the food, whereas, as a second feature, additional health benefits are expected from its regular ingestion. These kinds of food products are often called nutraceutical foods. In a rapidly changing world, with altered food habits and stressful life styles, it is more and more recognized that a healthy digestive system is essential for the overall quality of life (Brouns et al., 2002). Corresponding author. Tel.: +52 735 3942020; fax: +5273941896.
E-mail address: [email protected] (L.A. Bello-Pe´rez). 0889-1575/$ - see front matter r 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.jfca.2006.07.005
One of the current tendencies in nutrition and health is to consume low-carbohydrate food products. In the 1980s, dietary fiber was identified as an important component of a healthy diet, and the food industry looked for palatable ways to increase the fiber content of their products. The first commercially available product to provide a concentrated source of RS was reported in the mid 1990s. Nowadays, a number of industries prepare RS-rich powders using a technology developed by Prof. Paul Seib’s group, at Kansas State University (Shin et al., 2003). The patent covers a special type of modification applied to any starch derived from cereal grains, roots, tubers and legumes, such as wheat, corn, oat, rice, potato, tapioca and mung (Vigna radiata L.) bean. However, it should be kept in mind that the starch source may play an important role in the nutritional and functional properties of RS
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products. In this sense, the nutritional/nutraceutical potential of banana starch has been claimed by several authors (Englyst et al., 1992; Pacheco-Delahaye et al., 2004). Resistant starches are not digested in the human small intestine and are fermented by bacterial microflora in the large bowel, affecting a number of physiological functions and thus having different effects on health, e.g., reduction of the glycemic and insulinemic responses to food, hypocholesterolemic action and protective effects against colorectal cancer (Asp et al., 1996). In recent years, there has been a considerable interest in the possibility of improving control of diabetic patients by altering the glycemic impact of the carbohydrates ingested. A tool for ranking foods with respect to how they potentially raise blood glucose is the glycemic index (GI) concept (Jenkins et al., 1981), which leads to the preferred selection of ‘‘slow carbohydrate’’ food items/diets (Jenkins et al., 1981; Bjo¨rck et al., 1994). Although it cannot be regarded as a general rule, a nutritional variable that may be linked to low GI properties is the RS content of a food or complete meal (Truswell, 1992). Various RS types have been characterized in common foods. According to Englyst et al. (1992), these indigestible starch fractions may be classified according both to the nature of the starch and its environment in the food. Thus, RS1 corresponds to physically inaccessible starches, entrapped in a cellular matrix, as in cooked legume seeds, and RS2 are native uncooked granules of some starches, such as those in raw potatoes and green bananas, whose crystallinity makes them scarcely susceptible to hydrolysis. RS3, on the other hand, consists mainly of retrograded starch fractions, which may be formed in cooked foods that are kept at low or room temperature. More recently, a fourth type (RS4), has been associated to certain fractions of chemically modified starches (Tovar et al., 1999; Laurentı´ n et al., 2003). Resistant starch can be found in both processed and raw food materials. From the four RS types, RS3 seems to be particularly interesting because it retains its indigestibility when added as an ingredient to processed foods. RS3 is produced by a combination of the gelatinization process, which is a disruption of the granular structure by heating starch with an excess of water (Farhat et al., 2001); and retrogradation, a slow recrystalization of starch components (amylose and amylopectin) upon cooling or dehydration (Shamai et al., 2003). As it was mentioned before, modern food manufacturing methods destroy most forms of resistant starch, making them unsuitable as ingredients in highly processed food systems. This fact gives importance to the production of RS-rich powders that may be used in the formulation of diverse products. Potential applications for such a type of ingredient include breads, tortillas, pizza crust, cookies, muffins, waffles, breakfast cereals, snack products and nutritional bars, as well as lowfat fermented milks, ultra-heat treatment (UHT) flavored milk drinks, and ready-to-use powdered mixes, such as
instant soups and chocolate drinks. In a recent study, a resistant starch-rich powder (RSRP) was prepared from lintnerized banana starch, which retains its amylolysis resistant features after subsequent heat treatment (Aparicio-Saguila´n et al., 2005). Lintnerized starch is obtained by mild acid hydrolysis of both a-1,4 and a-1,6 glycosidic linkages of amylose and amylopectin, preferentially in the amorphous regions of granules (amylose and branched regions of amylopectin). Such a treatment leaves starch preparations with increased crystalline contents, which results in augmented resistance to enzymatic hydrolysis. The objective of this study was to evaluate starch digestibility and the in vitro predicted GI of cookies prepared with banana RSRP preparation. 2. Materials and methods 2.1. Banana starch isolation Banana starch was isolated using a previously described procedure (Flores-Gorosquera et al., 2004). Unripe (green) cooking bananas were purchased at the local market in Cuautla (Mexico); they were peeled, cut into 5–6 cm3 (100 kg total wt), immediately rinsed in citric acid solution (0.5 g/L) and then macerated at low speed in a Waring blender (10 kg fruit:10 L of solution) for 2 min. The homogenate was consecutively sieved through screens (20, 40, 100 and 200 US mesh) and washed with distilled water; it was then centrifuged in a semi-continuous Veronesi centrifuge (BSGAR 1500, Verona, Italy) at 10,750 rpm. The sediments from 100 and 200 US mesh were further purified by washing and additional centrifugation under the above-mentioned conditions. The white-starch sediments were dried in a spray dryer (Niro Atomizer, Model P-6.3, Copenhagen, Denmark), with a feeding temperature of 130–150 1C, a solid concentration in the feeding line of 30–40%, and an outlet temperature of 70–80 1C. The powder was ground to pass a US No. 100 sieve and stored at room temperature (25 1C) in a glass container. 2.2. Preparation of resistant starch-rich powder (RSRP) The RSRP was prepared as described by AparicioSaguila´n et al. (2005) from lintnerized banana starch. Lintner-modified starch (60 g) was mixed with 210 mL of water, and the mixture was pressure-cooked at 121 1C for 1 h in an autoclave. The mixture was cooled to room temperature and stored at 4 1C for 24 h. After three repetitions of the autoclaving and cooling cycles, the sample was freeze-dried and ground into fine particles (100 mesh US). 2.3. Preparation of cookies For the preparation of the cookies, raw materials were acquired in local supermarkets and stored in glass/plastic
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containers at room temperature (25 1C), or under refrigeration depending on the stored requirements of the material (Aparicio-Saguila´n et al., 2005). The formulation used for the cookies is shown in Table 1. In all cases, the products contained either wheat flour (control) (Gamesa, S.A. de C.V., Me´xico) or the wheat flour/RSRP mix. Margarine (containing a blend of vegetable oils, whey milk, soy lecithin, citric acid, etc.) was creamed, mixed with confectioner’s sugar and a whole egg, added to the wheat flour or the wheat flour/RSRP blend and mixed thoroughly; dough was rolled out to a 2 cm height on flat surface. Cookies were cut with a circular mold (6 cm diameter) and placed on greased aluminum cookie sheets. The cookies were baked in a household oven (Hotpoint, 6B4411LO, Leisser S.A. de C.V., San Luis Potosi, Me´xico), at an approximate temperature of 200 1C for 20 min. Once baked, cookies were allowed to cool down during 30 min and stored in a plastic container with hermetic cover. 2.4. Affective test on cookies with RSRP This test was applied to cookies prepared with different RSRP levels, with the purpose of choosing a suitable formulation for the next studies. Fifty non-trained students (35 females and 15 males, ages 18–23 years) chosen at random from Instituto Tecnolo´gico de Acapulco, took part in the trial, using a preference scale (4 ¼ like much, 3 ¼ like, 2 ¼ dislike, 1 ¼ dislike much). The cookies (2–3 g) were tested at random and identified with random numbers (Pedrero and Pangborn, 1989). When analysis showed significant differences (Po0.05), results were analyzed using a Friedman repeated measures analysis of variance on ranks procedure. Means were compared using Tukey’s tests. Statistical analyses were run using the computer SPSS V. 6.0 software (SPSS Institute Inc., Cary, NC). Once the proper cookie formulation was chosen, a second affective test (paired test) was carried out for comparing control and RSRP-cookie formulations. One hundred randomly chosen consumers (68 females and 32 males, age between 18 and 25 years) expressed their preference between both cookie formulations. The cookies (2–3 g) were tested at random and identified with random
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numbers (Pedrero and Pangborn, 1989). Statistical analysis was realized with Student t-test (Po0.05) using the SPSS program. 2.5. Chemical composition Moisture content was determined by gravimetric heating (13072 1C for 2 h) using a 2–3 g sample. Ash, protein and fat were analyzed according to AACC methods 08–01, 46–13, and 30–25, respectively (American Association of Cereal Chemists: Approved Methods of the AACC, 2000). 2.6. Digestibility tests Potentially available starch content was assessed following the multi-enzymatic protocol of Holm et al. (1986). The sample (300 mg db) was suspended in 20 mL of distilled water and incubated with a-amylase (Termamyls novo A/ S. Copenhagen) in a boiling water bath for 20 min. This mixture was then diluted to 100 mL with distilled water. In total, 0.5 mL of this suspension were mixed with amyloglucosidase (Boehringer, Mannheim, Germany) and 1.0 mL 0.1 mol/L Na acetate buffer, pH 4.75 was added. This mixture was incubated for 30 min at 60 1C. It was then diluted to 10 mL with distilled water and analyzed for glucose using the glucose oxidase peroxidase assay (SERAPAK Plus, Bayer de Me´xico, S.A. de C.V., Me´xico). Resistant starch was assessed by the method of Gon˜i et al. (1996), to estimate the total amount of indigestible starch (comprising RS2 and RS3 fractions). The method consists of the removal of protein with pepsin (P-7012, Sigma Chemical CO, St. Louis, MO) at 40 1C, 1 h pH 1.5, incubation with amylase (A-3176, Sigma Chemical CO, St. Louis, MO) at 37 1C for 16 h to hydrolyze digestible starch, treatment of the precipitate with 2 M KOH, incubation with amyloglucosidase (A-7255, Sigma Chemical CO, St. Louis, MO) at 60 1C, 45 min, pH 4.75 and determination of glucose using the glucose oxidase peroxidase assay (SERAPAK Plus, Bayer de Me´xico, S.A. de C.V, Me´xico). Soluble (SIF) and insoluble (IIF) indigestible fractions (IIFs) were assessed using the sequential pepsin/amylase hydrolysis method of Saura-Calixto et al. (2000); after the enzymatic treatments the sample was centrifuged and the residue
Table 1 Formulation of cookies with diverse resistant starch-rich powder (RSRP)* levels Ingredient (g)
Regular margarine Wheat flour RSRP Granulated sugar Whole egg *RSRP ¼ resistant starch-rich powder.
Control
22.5 44.9 0 15.7 16.8
Wheat flour:RSRP 35:65
25:75
15:85
10:90
22.5 15.7 29.2 15.7 16.8
22.5 11.2 33.7 15.7 16.8
22.5 6.7 38.2 15.7 16.8
22.5 4.5 40.4 15.7 16.8
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dried for gravimetric determination of the IIF. In order to calculate the SIF content, the supernatant was dialyzed and hydrolyzed with sulfuric acid for the assessment of reducing carbohydrate, using dinitrosalicilic acid. This method has been proposed as an alternative to enzymatic dietary fiber assays, aiming to include most of the physiologically indigestible part of foods, regardless of their chemical nature. The dietary fiber analysis measures non-*starch polysaccharides and lignin, whereas the IIF method also includes RS, indigestible protein, oligosaccharides, certain polyphenolic compounds, etc., that are not quantified in conventional DF tests. Starch hydrolysis index (HI) of products ‘‘as eaten’’ (chewing/dialysis test) was assessed with the protocol developed by Granfeldt et al. (1992). Samples of cookies containing 1 g of available starch were tested. Six healthy subjects (4 females and 2 males, ages between 20 and 22 years) participated in the chewing phase of the experiments, which was followed by pepsin digestion (P-7012, Sigma Chemical CO, St. Louis, MO) and incubation with porcine pancreatic amylase (A-6255, Sigma Chemical CO, St. Louis, MO) in a dialysis bag. The reducing amylolysis products appearing in the dialysate were measured colorimetrically, and expressed as maltose equivalents. Data were plotted as ‘‘hydrolysis degree’’ vs. ‘‘time’’ curves and the HI was calculated as the area under the curve (0–180 min) for the test product, expressed as a percentage of the corresponding area for a white bread reference sample, chewed by the same person. 2.7. Statistical analysis Results were expressed by means of values7standard error of three separate determinations. Comparison of means was performed by one-way analysis of variance (ANOVA) followed by Tukey’s test. The average HI was calculated from six digestion replicates runs for each sample and means were compared by the Wilcoxon matched-pair signed-rank test, each person being his own control. The predicted glycemic index (pGI) was calculated from HI values, using the empiric formula proposed by Granfeldt (1994): pGI ¼ 0.862 HI+8.198, for which the reported correlation coefficient (r) is 0.026 (Po0.00001). Statistical analyzes were run using the computer SPSS V. 6.0 software (SPSS Institute Inc., Cary, NC).
3. Results and discussion 3.1. Affective tests at cookies According to previous data, the banana RSRP preparation exhibits a resistant starch content of 19.34% (Aparicio-Saguila´n et al., 2005). Here, it was mixed with wheat flour in different proportions for cookie baking. The first affective test was carried out in order to choose the better taste formulation. Such a formulation was later evaluated in terms of chemical composition, starch digestibility, pGI and compared to a control wheat flour cookie by means of a second affective test. The statistical analysis of the first affective test (Table 2) showed that cookies prepared with the 35:65 and 15:85 (wheat flour:RSRP) proportions were preferred, with qualifications between 2.5 and 3.0 (Po0.05), although cookies prepared with the 35:65 and 25:75 ratios were accepted similarly. Therefore, the formulation with the highest RSRP level (15:85) was selected for further evaluation. The second affective test (Table 2) showed no difference in preference between the RSRP-cookie and control sample. Hence, besides its potential nutritional features, the RSRP-cookie has organoleptic acceptance by consumers. 3.2. Chemical composition The moisture content of the RSRP-cookie (5.70%) was slightly higher compared with the control sample (Table 3). This difference may be attributed to the particular formulation of each cookie, a fact that can be related to the relative abundance of amorphous starch zones in each material, which influences water absorption to a large extent (Slade and Levine, 1991). In a previous study from this group, a similar cookie type was prepared adding native corn or banana starches to wheat flour (Bello-Pe´rez et al., 2004), showing moisture levels that resemble those recorded here (4–5%). No difference (Po0.05) in fat content (12.55% and 12.69%) was detected between cookies (Table 3), which is in accordance with the equivalent margarine level used in both formulations. Similarly, the incorporation of RSRP did not produce a noticeable change in the final cookie ash content, reflecting the low mineral level in this ingredient
Table 2 Affective tests indices for cookies with diverse resistant starch-rich powder (RSRP*) levels** Test
First affective test: ANOVA on ranks Second affective test: t-student
Wheat flour:RSRP 35:65
25:75
15:85
10:90
2.5a,b
2.0b Wheat flour control 7.8270.45a
3.0a Wheat flour: RSRP (15:85) 6.9670.36a
1.0c
*RSRP ¼ resistant starch-rich powder. **Means in a row not sharing the same letter are significantly different (Po0.05).
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Sample Moisture Ash$ Protein$,& Lipid$ Available starch$ Resistant starch$ Insoluble indigestible fraction Soluble indigestible fraction Total indigestible fraction
Control cookie a
4.4970.34 0.3770.1a 11.970.40a 12.670.36a 37.270.40a 1.4870.05a 13.471.50a 3.4070.19a 16.870.92a
RSRP-cookie 5.7070.23b 0.4970.1a 5.0970.21b 12.770.01a 40.170.63b 8.4270.30b 20.571.04b 2.9270.13b 23.470.73b
*RSRP ¼ resistant starch-rich powder. **Dry matter basis. Values are means of three replicates7standard error. Means in row not sharing the same letter are significantly different (Po0.05). # RSRP:wheat flour ¼ 15:85. $ dry basis. & N 5.85.
(0.15%, Aparicio-Saguila´n et al., 2005). Although protein content (Table 3) in the control cookie (11.93%) was higher than in RSRP-containing sample (5.09%), this type of product is generally characterized by low protein contents and, evidently, the actual level depends on the formulation employed. Cookies formulated with banana and corn starches showed protein content between 6.18 and 9.2, respectively (Bello-Pe´rez et al., 2004). Other authors have reported protein content around 8–9% in cookies with grape skin added (Cannet-Romero et al., 2004). Potentially available starch in the RSRP-cookie was higher than in the control cookie (Table 3), although the difference is moderate (40% vs. 37%, respectively). Thus, RSRP appears to be a richer starch source (80% available starch content, Aparicio-Saguila´n et al., 2005) than wheat flour. Nonetheless, it should be mentioned that potentially AS is determined after fine grinding and boiling of the sample (Holm et al., 1988) and it therefore reports the sum of starch fractions that are readily available to enzymatic hydrolysis, plus RS1 and RS2 (Tovar and Velasco, 1995). Since the latter portions are not available for absorption in vivo (Englyst et al., 1992; Gon˜i et al., 1996), AS values in the RSRP-containing cookies may be larger than their actual digestible carbohydrate content. 3.3. Digestibility tests As expected, RS content in RSRP-cookies (8.42%) was markedly higher than in the control cookie (1.48%). These values indicate that RSRP contributes significantly to the final cookie RS content and confirm that the baking process does not alter this indigestible component. A˚kerberg et al. (1998) reported a 10.3% RS value in experimental bread; however, baking conditions in that study were chosen to produce no degradation of RS and to maximize its production due to the retrogradation
phenomenon. The use of native banana starch in cookie formulation resulted in up to 4.9% RS values (Bello-Pe´rez et al., 2004). The IIF was assessed as an alternative analysis for dietary fiber content (Saura-Calixto et al., 2000). The insoluble IIF for the control cookie was of 13.37% as compared to a 3.40% soluble indigestible fraction (SIF) level (Table 3). In the case of RSRP-cookie, the IIF was notably higher (20.5%), whereas only a slight difference in SIF was found between both cookies. The difference determined in total indigestible fraction (TIF) is in agreement with the different RS contents determined in these two products. Therefore, it can be concluded that the RSRP-cookie has considerable indigestible carbohydrate content. Enzymatic starch digestion curves for the different products are depicted in Fig. 1 and corresponding hydrolysis parameters are summarized in Table 4. White bread, used as reference, showed a digestion value of about 50% after 180 min, which agrees with the values reported in the original protocol by Granfeldt et al. (1992). Hydrolysis was markedly slow for RSRP-cookie and faster for the control cookie. Although the control-cookie and white bread showed similar hydrolysis rates until 90 min, the digestion velocity decreased for the control cookie thereafter, leading to a calculated HI of only 80.54. The low and slow hydrolysis of starch in the RSRP-cookie (60.71 HI) is noteworthy, since the digestion experiment was performed at equivalent AS levels. Thus, the presence of RS in this product seems to affect the susceptibility to digestion of the available starch portions. A similar situation was observed by Granfeldt et al. (1995) for high amylose arepas (corn bread). A HI of 73 was determined in barley bread (A˚kerberg et al., 1998), which is not too different from that of RSRP-cookie (Table 4), showing that glucose liberation from starch is lower in these samples than in white bread. This pattern is important in the mechanisms governing post-prandial glycemia for wheat flour based-products
60 50 Hydrolysis (%)
Table 3 Chemical composition of cookies with diverse resistant starch-rich powder (RSRP*) levels (%)**,#
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40 30 20 10 0 0
50
100
150
200
Time (min) Fig. 1. Average hydrolysis curves of: RSRP*-cookie (’), control cookie (m), white bread used as reference (E).
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Table 4 Hydrolysis index (HI) and predicted glycemic index (pGI) of cookies with diverse resistant starch-rich powder levels (RSRP*)**,& Sample
HI*
pGI#
Control cookie RSRP-cookie White bread reference
80.5472.64a 60.7172.28b 100c
77.62 60.53 94
*RSRP ¼ resistant starch-rich powder. **Hydrolysis index (HI) was related to bread ¼ 100 (Granfeldt et al., 1992). Values are mean of six chewing and dialysis replicates7standard error (Po0.05). & RSRP:wheat flour ¼ 15:85. # Predicted glucemic index (pIG) ¼ 0.862 HI+8.198 (Granfeldt, 1994). Means in columns not sharing the same letter are significantly different (Po0.05).
(Giacco et al., 2001) and foods with high RS content (Bjo¨rck and Liljeberg-Elmsta˚hl, 2003). The predicted GI value for the RSRP-sample (60.53) was below that determined in the control cookie (77.62). Predicted GI (Table 4) suggests important ‘‘slow digestion’’ features for the RSRP-cookie, which is in line with perceived health-beneficial characteristics of RS (Asp et al., 1996; Champ et al., 2003). The pGI value determined in RSRP-cookie suggests that this product has a low in vivo GI. Higher pGI values were determined in two barley breads containing different amylose/amylopectin ratio (A˚kerberg et al., 1998). Also, a GI value of 81 has been reported for energy bars (Foster-Powell et al., 2002), which is quite a bit higher than that recorded here for the RSRPcookie. In addition to the intrinsic properties of starch in the RSRP, the possible influence of the product compactness on the observed HI and pGI values cannot be ruled out. This might result in a slower diffusion of in vivo amylolytic products to the absorptive mucosa, as it has been demonstrated for other types of products (Bjo¨rck et al., 1994; Jenkins et al., 1987). The combined action of these factors results in moderate glycemic responses.
4. Conclusions A bakery product showing moderate available starch and slow release carbohydrate features was prepared using a resistant starch-rich powder (RSRP) from banana starch. The use of nutraceutical ingredients, such as RSRPs, may be useful in the development of new products for population sectors with reduced caloric and glycemic requirements.
Acknowledgments We appreciate the economic support from CGPI-IPN, COSNET-Me´xico, COFAA-IPN, EDI-IPN and LANFOODS.
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