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Encapsulation of Orange Peel Oil by Co-crystallization
Lebensm.-Wiss. u.-Technol., 29, 645–647 (1996)
Encapsulation of Orange Peel Oil by Co-crystallization Cesar ´ I. Beristain*, Alma Vazquez, Hugo S. Garcia and Eduardo J. Vernon-Carter C. I. Beristain, A. Vazquez: Instituto de Ciencias Basicas, ´ Universidad Veracruzana, Apartado Postal 575, Xalapa, Ver (Mexico) ´ H. S. Garcia: Departamento de Ingenieria Quimica y Bioquimica, ITV, Veracruz, Ver (Mexico) ´ E. J. Vernon-Carter: Universidad Autonoma ´ Metropolitana-Iztapalapa, DCBI, D.F. (Mexico) ´ (Received July 31, 1995; accepted December 8, 1995)
Orange peel oil was microencapsulated by co-crystallization. Encapsulation capacity of sucrose syrups was found to be greater than 90% for a range of 100 to 250 g oil/kg of sugar. Surface oil, a measurement of encapsulation efficiency, varied from 3350 to 8880 mg oil/kg solids. Moisture content of the crystals was lower than 10 g/kg and bulk density was greater than 670 kg/m3 for all the co-crystallizates prepared. Sensory evaluation showed that all of the panelists were able to detect oxidized flavours in oils without antioxidant added after storage at 35 °C for 1 d. When butylated hydroxyanisole (BHA) was added to the oil prior to cocrystallization, no signs of oxidized flavours were detected after 2 months of storage at ambient temperature. ©1996 Academic Press Limited
Derivados Veracruzanos Mexico).
Introduction The encapsulation of food flavours presents a unique, challenging area of investigation. Commercial production of encapsulated flavours is accomplished by a variety of methods: spray-drying, extrusion, coacervation and adsorption techniques are among the most widely used (1). Encapsulation of flavours via cocrystallization is a relatively new method that offers an economical and flexible alternative since the procedure is relatively simple (2). During recent years, a small number of studies have reported on the encapsulation process by co-crystallization (3–5), in which the crystal structure of sucrose is modified from a perfect crystal to a conglomerate. This structure provides a porous configuration which can accept the addition of a second ingredient. Careful incorporation of the second ingredient is also very important (4) since it plays two major roles in the production of co-crystallizates: first, it inhibits premature sucrose crystallization, allowing the process to proceed at manageable and reproducible rates; and second it improves the functionality of the co-crystallized product. The objective of this study was to evaluate the cocrystallization process for the encapsulation of orange peel oil with sucrose.
Materials and Methods Raw materials Single strength orange peel oil was obtained from *To whom correspondence should be addressed.
0023-6438/96/070645 + 03$25.00/0
S.A.
de
C.V.
(Xalapa,
Co-crystallization Experiments were performed in 100 g batches of mixture. A sucrose syrup of 70 °Brix was concentrated by heating on a hot plate with magnetic stirring until a concentration greater than 95 °Brix was attained. Then the core material (orange peel oil) was added at ratios of 100, 150, 170, 200 and 250 g of oil/kg sugar, using a Cole Parmer high shear mixer at position 1, until crystallization occurred. Once crystallization started, heating was stopped and the heat of crystallization facilitated water elimination until a dry granular product was obtained. BHA was added before the orange peel was incorporated into the sucrose syrup BHA was added at a concentration of 0.2 g/kg peel oil to protect against autoxidation. Moisture Moisture content of the powders was determined by the toluene distillation method. A 40 g sample of powder was added to 250 mL of toluene in a 500 mL flask. The flask was fitted with a Bidwell-Stearling trap and the sample brought to the boil on a hot plate. Water distillation was carried out for 3 h and the volume of water collected was recorded. Total oil Total oil in the powders was determined using a clevenger apparatus. Twenty grams of powder were dissolved in 150 mL of distilled water in a 250 mL flask. A few boiling spheres and ca. 0.5 mL antifoam (silicone ©1996 Academic Press Limited
645
lwt/vol. 29 (1996) No. 7
oil, Aldrich) were added. A clevenger oil trap and water cooled condenser were attached. The solution was slowly brought to the boil and allowed to distill for 3 h. The oil volume, read directly from the oil collection arm, was converted to weight by multiplying by its density (846 kg/m3).
Bulk density Bulk density was determined by the tapping method. Thirty grams of powder were loosely weighed and placed into a 100 mL graduated cylinder. The cylinder was tapped on a flat surface to a constant volume of powder. The final volume was recorded and bulk density was calculated by dividing the samples weight by the volume. Sensory evaluation Sensory evaluation of the samples was done by the paired comparison test, using a panel of eight members trained to detect oxidized orange peel oil flavour. Encapsulated samples stored at 35 °C were evaluated against control samples stored at 4 °C. Appropriate amounts of the stored co-crystallized products were dissolved in cold water such that the final concentration of the oil in the solution was 50 mg/L. The judges were asked to chose the sample having the oxidized flavour. When all of the panelists detected the oxidized flavour in the samples, that time was taken as the end of the samples shelf-life. Results and Discussion Co-crystallization can be described according to Beristain et al. (5) using the solubility diagram of sucrose as presented in Fig. 1. In the figure the degree of supersaturation of a sugar solution is measured in terms of the supersaturation coefficient (S), where: S =
Concentration (w/w) of sugar in water at a given temperature Concentration (w/w) of sugar in water in a saturated solution at the same temperature
Eqn [1]
The solution is supersaturated if S > 1, and S = 1 defines the solubility curve. The metastable zone comprises the range of S from 1.0 to 1.25, in which conditions permit only the growth of existing crystals, but not allowing formation of new nucleii. At the same temperature and as sugar concentration is increased from C.A. to C.M, crystallization rates increase toward the points A, B, C and M, where the maximum crystallization rate is
Labile zone Concentration
Surface oil Surface oil in the unencapsulated oil was determined gravimetrically. Thirty grams of powder were placed in an extraction thimble and covered with glass wool. The powder was extracted with hexane for 4 h. Each extract was evaporated to dryness in a water-bath at 30 °C using a stream of nitrogen and then dried in a vacuum oven at 60 °C for 24 h. The residue or surface oil was determined by direct weighing of the residue.
1.25 1.2 1.15 1.1 1.0
C.M C.C C.B C.A C.O
M C B A O
e
ble
sta ta-
zon
Me
Zone of unsaturation T Temperature
Fig. 1 Solubility diagram for sucrose
found. At point ‘O’ on the saturation line, crystallization is nill. The labile zone is located at S > 1.25, where crystallization rates are so high that spontaneous nucleation occurs. When sugar concentrations are maintained constant and temperature is decreased, S increases; conversely at higher temperatures S is smaller and sugars go into solution. At constant temperature, increased sugar concentrations elevate S and upon dilution, S becomes smaller. During cocrystallization, the orange peel oil was added when the concentrated syrup was at the supersaturation zone that corresponds to the labile zone. This induced formation of irregular agglomerates which resulted from uncontrolled crystallization rates. These structural irregularities were suitable for entrapping the second nonsugar ingredient. The width of the meta-stable zone depends on the purity of the sugar solution, being narrower for pure sucrose solutions. Above this zone, and in the labile region, co-crystallization may be carried out since the rate of crystal formation is so high that nuclei form spontaneously and without control. Results of the total oil, surface oil, moisture and density are presented in Table 1. All values represent the average of three samples. It can be noted that the proportion of encapsulated oil varies with the initial amount of oil added to the sucrose solution from 86 g/kg powder (94.6% of the starting oil) to 188 g/kg powder (94.0% of the starting oil). When compared to other encapsulation processes, the co-crystallization products can retain amounts of volatile oil as high as those reported for spray-dried products, which typically yield products with volatile oil contents ranging from 150–200 g/kg, depending on the wall material (6–8). Extruded products contain volatile oil in the range of Table 1 Encapsulation performance crystallization of orange peel oil
for
the
co-
Starting oil (g/kg)
Total oil (g/kg)
Surface oil (mg/kg oil)
Moisture Bulk density (g/kg) (kg/m3)
90.9 130.4 166.6 200.0
86.0 120 154 188
3350 5333 6940 8888
6.0 7.0 7.5 8.0
646
752.3 718.2 700.4 674.4
lwt/vol. 29 (1996) No. 7
80–100 g/kg and for a β-cyclodextrin complex a lower volatile oil content of 82 g/kg has been reported (9). Surface oil increased as the amount of peel oil was increased, starting at 3350 mg/kg crystals for 9% starting oil to 8880 mg/kg crystals for 20% starting oil. It has generally been accepted that shelf-life is related to surface oil because it is not protected from oxygen. However, controversy exists because it has been reported that surface oil is not the primary determinant for oxidative stability (10–12). Moisture content of the crystals was lower than 10 g/kg and bulk density, as determined by the tapping method, ranged from 674.4 to 752.3 kg/cm3. Density increased as the amount of sucrose increased. These values were higher than those reported when spray-drying was used with a modified food starch as wall material (13) and those for gum Arabic and mesquite gum (14). Results from the sensory evaluation showed that all of the panelists were able to detect oxidized flavours in plain co-crystallizates to which 100 and 250 g oil/kg sugar were added after 3 and 1 d, respectively. However, when BHA was added as an antioxidant, no flavour changes were detected after a storage period of 2 months. Chen et al. (3) reported no significant changes in flavour retention after 15 weeks of storage for three different orange-based flavours, synthetic peppermint oil, and natural lemon flavour in cocrystallized products packed and stored in polyethylene bags under ambient conditions. However, the authors measured retention in encapsulated oil, but did not analyse the oils for compounds associated with development of oxidized flavours. According to Reineccius (15), probably the major determinant of shelf-life in this type of product is the porosity of the particle to oxygen, and in this case porosity of the co-crystallizates may be too high so that oxygen can easily reach the oil. Conclusions Orange peel oil co-crystallizates prepared in this work were granular, easy to handle, had good flowing characteristics and did not form aggregates. The crystals retained all the orange oil and colour distinctive of the original product; however, addition of a strong antioxidant is necessary to retard development of oxidized flavours during storage. The co-crystallizate is oxidation-prone probably due to its porous structure which does not offer any barrier to oxygen diffusion. References 1 ANANDARAMAN, S. AND REINECCIUS, G. A. Microencapsulation of flavour. Food Flavourings Ingredients. Pack. Process, 2, 14, 17–18, 25 (1980)
2 JACKSON, L. S. AND LEE, K. Microencapsulation in the food industry. Lebensmittel-Wissenschaft und-Technologie, 24, 289–297 (1991) 3 CHEN, A. C., VEIGA, M. F. AND RIZZUTO, A. R. Cocrystallization: An encapsulation process. Food Technology, 42, 87–90 (1988) 4 AWAD, A. AND CHEN, A. A new generation of sucrose products made by co-crystallization. Food Technology, 47, 146–148 (1993) 5 BERISTAIN, C. I., MENDOSA, R. E., GARCIA, H. S. AND VAZQUEZ, A. Co-crystallization of jamaica (Hibiscus sabdarifa L.) granules. Lebensmittel-Wissenschaft undTechnologie, 27, 347–349 (1994) 6 TRUBIANO, P. C. AND LACOURSE, N. L. Emulsion-stabilizing starches: Use in flavour encapsulation. In: RISCH, S. J. AND REINECCIUS, G. A. (Eds), Flavour Encapsulation. Washington, D.C.: ACS Symposium Series 370, American Chemical Society, pp. 45–54 (1988) 7 RISCH, S. J. AND REINECCIUS, G. A. Encapsulated orange oil: Effect of emulsion size on flavour retention and shelf stability. In: RISCH, S. J. AND REINECCIUS, G. A. (Eds), Flavour Encapsulation. Washington D.C.: ACS Symposium Series 370, American Chemical Society, pp. 67–77 (1988) 8 BERISTAIN, C. I. AND VERNON-CARTER, E. J. Studies on the interaction of arabic (Acacia senegal) and mesquite (Prosopis juliflora) gum as emulsion stabilizing agents for spray-dried encapsulated orange peel oil. Drying Technology, 13, 455–461 (1995) 9 WESTING, L. L., REINECCIUS, G. A. AND CAPORASO, F. Shelf life of orange oil: Effects of encapsulation by spray-drying, extrusion, and molecular inclusion. In: RISCH, S. J. AND REINECCIUS, G. A. (Eds), Flavour Encapsulation. Washington D.C.: ACS Symposium Series 370, American Chemical Society, pp. 110–121 (1988) 10 ANANDARAMAN, S. AND REINECCIUS, G. A. Stability of encapsulated orange peel oil. Food Technology, 40, 88–93 (1986) 11 INGLET, G. E., GELBMAN, P. AND REINECCIUS, G. A. Encapsulation of orange oil: Use of oligosaccharides from α-amylase modified starches of maize, rice, cassava and potato. In: RISCH, S. J. AND REINECCIUS, G. A., (Eds), Flavour Encapsulation. Washington D.C.: ACS Symposium Series 370, American Chemical Society, pp. 29–36 (1988) 12 ANKER, M. H. AND REINECCIUS, G. A. Influence of spray dryer air temperature on the retention and shelf life of encapsulated orange peel oil. In: RISCH, S. J. AND REINECCIUS, G. A. (Eds), Flavour Encapsulation. Washington D.C.: ACS Symposium Series 370, American Chemical Society, pp. 78–86 (1988) 13 CHANG, Y. I., SCIRE, J. AND JACOBS, B. Effect of particle size and microstructure properties on encapsulated orange peel oil. In: RISCH, S. J. AND REINECCIUS, G. A. (Eds), Flavour Encapsulation. Washington D.C.: ACS Symposium Series 370, American Chemical Society, pp. 87–102 (1988) 14 BERISTAIN, C. I. AND VERNON-CARTER, E. J. Utilization of Mesquite (Prosopis juliflora) gum as emulsion stabilizing agent for spray dried encapsulated orange peel oil. Drying Technology, 12, 1727–1733 (1994) 15 REINECCIUS, G. A. Spray-drying of food flavours. In: RISCH, S. J. AND REINECCIUS, G. A. (Eds), Flavour Encapsulation. Washington D.C.: ACS Symposium Series 370, American Chemical Society, pp. 55–66 (1988)
647
Encapsulation of Orange Peel Oil by Co-crystallization Cesar ´ I. Beristain*, Alma Vazquez, Hugo S. Garcia and Eduardo J. Vernon-Carter C. I. Beristain, A. Vazquez: Instituto de Ciencias Basicas, ´ Universidad Veracruzana, Apartado Postal 575, Xalapa, Ver (Mexico) ´ H. S. Garcia: Departamento de Ingenieria Quimica y Bioquimica, ITV, Veracruz, Ver (Mexico) ´ E. J. Vernon-Carter: Universidad Autonoma ´ Metropolitana-Iztapalapa, DCBI, D.F. (Mexico) ´ (Received July 31, 1995; accepted December 8, 1995)
Orange peel oil was microencapsulated by co-crystallization. Encapsulation capacity of sucrose syrups was found to be greater than 90% for a range of 100 to 250 g oil/kg of sugar. Surface oil, a measurement of encapsulation efficiency, varied from 3350 to 8880 mg oil/kg solids. Moisture content of the crystals was lower than 10 g/kg and bulk density was greater than 670 kg/m3 for all the co-crystallizates prepared. Sensory evaluation showed that all of the panelists were able to detect oxidized flavours in oils without antioxidant added after storage at 35 °C for 1 d. When butylated hydroxyanisole (BHA) was added to the oil prior to cocrystallization, no signs of oxidized flavours were detected after 2 months of storage at ambient temperature. ©1996 Academic Press Limited
Derivados Veracruzanos Mexico).
Introduction The encapsulation of food flavours presents a unique, challenging area of investigation. Commercial production of encapsulated flavours is accomplished by a variety of methods: spray-drying, extrusion, coacervation and adsorption techniques are among the most widely used (1). Encapsulation of flavours via cocrystallization is a relatively new method that offers an economical and flexible alternative since the procedure is relatively simple (2). During recent years, a small number of studies have reported on the encapsulation process by co-crystallization (3–5), in which the crystal structure of sucrose is modified from a perfect crystal to a conglomerate. This structure provides a porous configuration which can accept the addition of a second ingredient. Careful incorporation of the second ingredient is also very important (4) since it plays two major roles in the production of co-crystallizates: first, it inhibits premature sucrose crystallization, allowing the process to proceed at manageable and reproducible rates; and second it improves the functionality of the co-crystallized product. The objective of this study was to evaluate the cocrystallization process for the encapsulation of orange peel oil with sucrose.
Materials and Methods Raw materials Single strength orange peel oil was obtained from *To whom correspondence should be addressed.
0023-6438/96/070645 + 03$25.00/0
S.A.
de
C.V.
(Xalapa,
Co-crystallization Experiments were performed in 100 g batches of mixture. A sucrose syrup of 70 °Brix was concentrated by heating on a hot plate with magnetic stirring until a concentration greater than 95 °Brix was attained. Then the core material (orange peel oil) was added at ratios of 100, 150, 170, 200 and 250 g of oil/kg sugar, using a Cole Parmer high shear mixer at position 1, until crystallization occurred. Once crystallization started, heating was stopped and the heat of crystallization facilitated water elimination until a dry granular product was obtained. BHA was added before the orange peel was incorporated into the sucrose syrup BHA was added at a concentration of 0.2 g/kg peel oil to protect against autoxidation. Moisture Moisture content of the powders was determined by the toluene distillation method. A 40 g sample of powder was added to 250 mL of toluene in a 500 mL flask. The flask was fitted with a Bidwell-Stearling trap and the sample brought to the boil on a hot plate. Water distillation was carried out for 3 h and the volume of water collected was recorded. Total oil Total oil in the powders was determined using a clevenger apparatus. Twenty grams of powder were dissolved in 150 mL of distilled water in a 250 mL flask. A few boiling spheres and ca. 0.5 mL antifoam (silicone ©1996 Academic Press Limited
645
lwt/vol. 29 (1996) No. 7
oil, Aldrich) were added. A clevenger oil trap and water cooled condenser were attached. The solution was slowly brought to the boil and allowed to distill for 3 h. The oil volume, read directly from the oil collection arm, was converted to weight by multiplying by its density (846 kg/m3).
Bulk density Bulk density was determined by the tapping method. Thirty grams of powder were loosely weighed and placed into a 100 mL graduated cylinder. The cylinder was tapped on a flat surface to a constant volume of powder. The final volume was recorded and bulk density was calculated by dividing the samples weight by the volume. Sensory evaluation Sensory evaluation of the samples was done by the paired comparison test, using a panel of eight members trained to detect oxidized orange peel oil flavour. Encapsulated samples stored at 35 °C were evaluated against control samples stored at 4 °C. Appropriate amounts of the stored co-crystallized products were dissolved in cold water such that the final concentration of the oil in the solution was 50 mg/L. The judges were asked to chose the sample having the oxidized flavour. When all of the panelists detected the oxidized flavour in the samples, that time was taken as the end of the samples shelf-life. Results and Discussion Co-crystallization can be described according to Beristain et al. (5) using the solubility diagram of sucrose as presented in Fig. 1. In the figure the degree of supersaturation of a sugar solution is measured in terms of the supersaturation coefficient (S), where: S =
Concentration (w/w) of sugar in water at a given temperature Concentration (w/w) of sugar in water in a saturated solution at the same temperature
Eqn [1]
The solution is supersaturated if S > 1, and S = 1 defines the solubility curve. The metastable zone comprises the range of S from 1.0 to 1.25, in which conditions permit only the growth of existing crystals, but not allowing formation of new nucleii. At the same temperature and as sugar concentration is increased from C.A. to C.M, crystallization rates increase toward the points A, B, C and M, where the maximum crystallization rate is
Labile zone Concentration
Surface oil Surface oil in the unencapsulated oil was determined gravimetrically. Thirty grams of powder were placed in an extraction thimble and covered with glass wool. The powder was extracted with hexane for 4 h. Each extract was evaporated to dryness in a water-bath at 30 °C using a stream of nitrogen and then dried in a vacuum oven at 60 °C for 24 h. The residue or surface oil was determined by direct weighing of the residue.
1.25 1.2 1.15 1.1 1.0
C.M C.C C.B C.A C.O
M C B A O
e
ble
sta ta-
zon
Me
Zone of unsaturation T Temperature
Fig. 1 Solubility diagram for sucrose
found. At point ‘O’ on the saturation line, crystallization is nill. The labile zone is located at S > 1.25, where crystallization rates are so high that spontaneous nucleation occurs. When sugar concentrations are maintained constant and temperature is decreased, S increases; conversely at higher temperatures S is smaller and sugars go into solution. At constant temperature, increased sugar concentrations elevate S and upon dilution, S becomes smaller. During cocrystallization, the orange peel oil was added when the concentrated syrup was at the supersaturation zone that corresponds to the labile zone. This induced formation of irregular agglomerates which resulted from uncontrolled crystallization rates. These structural irregularities were suitable for entrapping the second nonsugar ingredient. The width of the meta-stable zone depends on the purity of the sugar solution, being narrower for pure sucrose solutions. Above this zone, and in the labile region, co-crystallization may be carried out since the rate of crystal formation is so high that nuclei form spontaneously and without control. Results of the total oil, surface oil, moisture and density are presented in Table 1. All values represent the average of three samples. It can be noted that the proportion of encapsulated oil varies with the initial amount of oil added to the sucrose solution from 86 g/kg powder (94.6% of the starting oil) to 188 g/kg powder (94.0% of the starting oil). When compared to other encapsulation processes, the co-crystallization products can retain amounts of volatile oil as high as those reported for spray-dried products, which typically yield products with volatile oil contents ranging from 150–200 g/kg, depending on the wall material (6–8). Extruded products contain volatile oil in the range of Table 1 Encapsulation performance crystallization of orange peel oil
for
the
co-
Starting oil (g/kg)
Total oil (g/kg)
Surface oil (mg/kg oil)
Moisture Bulk density (g/kg) (kg/m3)
90.9 130.4 166.6 200.0
86.0 120 154 188
3350 5333 6940 8888
6.0 7.0 7.5 8.0
646
752.3 718.2 700.4 674.4
lwt/vol. 29 (1996) No. 7
80–100 g/kg and for a β-cyclodextrin complex a lower volatile oil content of 82 g/kg has been reported (9). Surface oil increased as the amount of peel oil was increased, starting at 3350 mg/kg crystals for 9% starting oil to 8880 mg/kg crystals for 20% starting oil. It has generally been accepted that shelf-life is related to surface oil because it is not protected from oxygen. However, controversy exists because it has been reported that surface oil is not the primary determinant for oxidative stability (10–12). Moisture content of the crystals was lower than 10 g/kg and bulk density, as determined by the tapping method, ranged from 674.4 to 752.3 kg/cm3. Density increased as the amount of sucrose increased. These values were higher than those reported when spray-drying was used with a modified food starch as wall material (13) and those for gum Arabic and mesquite gum (14). Results from the sensory evaluation showed that all of the panelists were able to detect oxidized flavours in plain co-crystallizates to which 100 and 250 g oil/kg sugar were added after 3 and 1 d, respectively. However, when BHA was added as an antioxidant, no flavour changes were detected after a storage period of 2 months. Chen et al. (3) reported no significant changes in flavour retention after 15 weeks of storage for three different orange-based flavours, synthetic peppermint oil, and natural lemon flavour in cocrystallized products packed and stored in polyethylene bags under ambient conditions. However, the authors measured retention in encapsulated oil, but did not analyse the oils for compounds associated with development of oxidized flavours. According to Reineccius (15), probably the major determinant of shelf-life in this type of product is the porosity of the particle to oxygen, and in this case porosity of the co-crystallizates may be too high so that oxygen can easily reach the oil. Conclusions Orange peel oil co-crystallizates prepared in this work were granular, easy to handle, had good flowing characteristics and did not form aggregates. The crystals retained all the orange oil and colour distinctive of the original product; however, addition of a strong antioxidant is necessary to retard development of oxidized flavours during storage. The co-crystallizate is oxidation-prone probably due to its porous structure which does not offer any barrier to oxygen diffusion. References 1 ANANDARAMAN, S. AND REINECCIUS, G. A. Microencapsulation of flavour. Food Flavourings Ingredients. Pack. Process, 2, 14, 17–18, 25 (1980)
2 JACKSON, L. S. AND LEE, K. Microencapsulation in the food industry. Lebensmittel-Wissenschaft und-Technologie, 24, 289–297 (1991) 3 CHEN, A. C., VEIGA, M. F. AND RIZZUTO, A. R. Cocrystallization: An encapsulation process. Food Technology, 42, 87–90 (1988) 4 AWAD, A. AND CHEN, A. A new generation of sucrose products made by co-crystallization. Food Technology, 47, 146–148 (1993) 5 BERISTAIN, C. I., MENDOSA, R. E., GARCIA, H. S. AND VAZQUEZ, A. Co-crystallization of jamaica (Hibiscus sabdarifa L.) granules. Lebensmittel-Wissenschaft undTechnologie, 27, 347–349 (1994) 6 TRUBIANO, P. C. AND LACOURSE, N. L. Emulsion-stabilizing starches: Use in flavour encapsulation. In: RISCH, S. J. AND REINECCIUS, G. A. (Eds), Flavour Encapsulation. Washington, D.C.: ACS Symposium Series 370, American Chemical Society, pp. 45–54 (1988) 7 RISCH, S. J. AND REINECCIUS, G. A. Encapsulated orange oil: Effect of emulsion size on flavour retention and shelf stability. In: RISCH, S. J. AND REINECCIUS, G. A. (Eds), Flavour Encapsulation. Washington D.C.: ACS Symposium Series 370, American Chemical Society, pp. 67–77 (1988) 8 BERISTAIN, C. I. AND VERNON-CARTER, E. J. Studies on the interaction of arabic (Acacia senegal) and mesquite (Prosopis juliflora) gum as emulsion stabilizing agents for spray-dried encapsulated orange peel oil. Drying Technology, 13, 455–461 (1995) 9 WESTING, L. L., REINECCIUS, G. A. AND CAPORASO, F. Shelf life of orange oil: Effects of encapsulation by spray-drying, extrusion, and molecular inclusion. In: RISCH, S. J. AND REINECCIUS, G. A. (Eds), Flavour Encapsulation. Washington D.C.: ACS Symposium Series 370, American Chemical Society, pp. 110–121 (1988) 10 ANANDARAMAN, S. AND REINECCIUS, G. A. Stability of encapsulated orange peel oil. Food Technology, 40, 88–93 (1986) 11 INGLET, G. E., GELBMAN, P. AND REINECCIUS, G. A. Encapsulation of orange oil: Use of oligosaccharides from α-amylase modified starches of maize, rice, cassava and potato. In: RISCH, S. J. AND REINECCIUS, G. A., (Eds), Flavour Encapsulation. Washington D.C.: ACS Symposium Series 370, American Chemical Society, pp. 29–36 (1988) 12 ANKER, M. H. AND REINECCIUS, G. A. Influence of spray dryer air temperature on the retention and shelf life of encapsulated orange peel oil. In: RISCH, S. J. AND REINECCIUS, G. A. (Eds), Flavour Encapsulation. Washington D.C.: ACS Symposium Series 370, American Chemical Society, pp. 78–86 (1988) 13 CHANG, Y. I., SCIRE, J. AND JACOBS, B. Effect of particle size and microstructure properties on encapsulated orange peel oil. In: RISCH, S. J. AND REINECCIUS, G. A. (Eds), Flavour Encapsulation. Washington D.C.: ACS Symposium Series 370, American Chemical Society, pp. 87–102 (1988) 14 BERISTAIN, C. I. AND VERNON-CARTER, E. J. Utilization of Mesquite (Prosopis juliflora) gum as emulsion stabilizing agent for spray dried encapsulated orange peel oil. Drying Technology, 12, 1727–1733 (1994) 15 REINECCIUS, G. A. Spray-drying of food flavours. In: RISCH, S. J. AND REINECCIUS, G. A. (Eds), Flavour Encapsulation. Washington D.C.: ACS Symposium Series 370, American Chemical Society, pp. 55–66 (1988)
647