Microencapsulation of β‐carotene using native pinhão starch,modified pinhão starch and gelatin by freeze‐drying

Beta‐carotene was microencapsulated by freeze‐drying using native pinhão starch, hydrolysed pinhão starch 6 dextrose equivalent (DE), hydrolysed pinhão starch 12 DE and the mixture of these materials with gelatin as coating material. The purpose of this research was to produce and characterize these microcapsules. The capsules’ efficiency, surface content, moisture, morphology, solubility, particle size and glass transition temperature were analysed. The hydrolysed pinhão starch 12 DE showed the highest total β‐carotene content and the lowest surface β‐carotene content, unlike the native starch. Using scanning electron microscopy, it was observed that all microcapsules presented undefined shapes. The samples with gelatin had wider particle size distribution, higher diameters, lower solubility and higher glass transition temperature when compared with other the samples. Results obtained suggest that the modified pinhão starch can be considered as potential wall material for encapsulation of β‐carotene.     

Enzyme stability of microencapsulated Bifidobacterium animalis ssp. lactis Bb12 after freeze drying and during storage in low water activity at room temperature

Abstract: Stability of enzymes such as β‐galactosidase (β‐gal), β‐glucosidase (β‐glu), lactate dehydrogenase (LDH), pyruvate kinase (PK), hexokinase (HK), and ATPase of microencapsulated Bifidobacterium animalis ssp. lactis Bb12 after freeze‐drying and after 10 wk of storage at low water activity (a_w) at room temperature was studied. Bacteria were microencapsulated using alginate formulation with or without mannitol fortification (sodium alginate and mannitol [SAM] and sodium alginate [SA], respectively) by creating gel beads followed by freeze drying. Two types of dried gel beads were then stored at low a_w, such as 0.07, 0.1, and 0.2; storage in an aluminum foil was used as control. All storage was carried out at room temperature of 25 °C for 10 wk. Measurement of β‐gal, β‐glu, LDH, PK, HK, and ATPase (with or without exposure to pH 2.0 for 2 h) activities was carried out before freeze drying, after freeze drying, and after 10 wk of storage. There was a significant decrease in almost all enzyme activities, except that of PK. SAM and SA showed no different effect on maintaining enzyme activities during freeze drying. Storage for 10 wk at room temperature at various low a_w using SAM and SA system had a significant effect on retention of most enzymes studied, except that of PK and LDH. Storage at a_w of 0.07 and 0.1 was more effective in maintaining enzyme activities than storage at a_w of 0.2 and in an aluminum foil. However, mannitol fortification into alginate system did not significantly improve retention of enzymes during 10 wk of storage.     

Stability of anthocyanins in frozen and freeze-dried raspberries during long-term storage: in relation to glass transition

Abstract: Anthocyanins, natural plant pigments in the flavonoid group, are responsible for the red color and some of the nutraceutical benefits of raspberries. This study explores anthocyanin degradation in frozen and freeze‐dried raspberries during storage in relation to glass transition temperatures. Frozen raspberries were stored at ?80, ?35, and ?20 °C, while freeze‐dried raspberries were stored at selected water activity (a_w) values ranging from 0.05 to 0.75 at room temperature (23 °C) for more than a year. The characteristic glass transition temperatures (T′_g) of raspberries with high water content and glass transition temperature (T_g) of raspberries with small water content were determined using a differential scanning calorimeter. The pH differential method was used to determine the quantity of anthocyanins in frozen and freeze‐dried raspberries at selected time intervals. The total anthocyanins in raspberries fluctuated during 378 d of storage at ?20 and ?35, and ?80 °C. Anthocyanin degradation in freeze‐dried raspberries ranged from 27% to 32% and 78% to 89% at a_w values of 0.05 to 0.07 and 0.11 to 0.43, respectively, after 1 y. Anthocyanins were not detectable in freeze‐dried raspberries stored at a_w values of 0.53 to 0.75 after 270 d. First order and Weibull equations were used to fit the anthocyanin degradation in freeze‐dried raspberries. The 1^st‐order rate constant (k) of anthocyanin degradation ranged from 0.003 to 0.023 days^?1 at the selected water activities. Significant anthocyanin degradation occurred in both the glassy and rubbery states of freeze‐dried raspberries during long‐term storage. However, the rate of anthocyanin degradation in freeze‐dried raspberries stored in the glassy state was significantly smaller than the rate of anthocyanin degradation in the rubbery state.     

In vitro bioaccessibility of β‐carotene in dried carrots pretreated by different methods

The effects of selected pretreatment methods, i.e. soaking in citric acid, blanching in water and blanching in citric acid, as well as hot‐air drying (at 70, 80 and 90 °C), on the retention and relative in vitro bioaccessibility of β‐carotene in dried carrots were investigated. The results indicated that the selected pretreatments and drying could enhance the relative bioaccessibility of β‐carotene in dried carrots. The relative bioaccessibility of β‐carotene in dried carrots increased to 47–73%, while the values in the fresh (13%) and dried untreated (31–47%) carrots were lower. Although significant losses of β‐carotene occurred during both the pretreatment and drying processes, bioaccessible β‐carotene contents of dried pretreated carrots were in a similar order to those of the fresh carrots, indicating the ability and hence the benefit of appropriate pretreatment and drying processes in maintaining the nutritive quality of a food product.     

Cover Caption

On the cover: SEM micrograph of freeze‐dried maltodextrin system prefrozen at ?80 °C prior to freeze‐drying, from “Porosity and Water Activity Effects on Stability of Crystalline β‐carotene in Freeze‐dried Solids” by Nathdanai Harnkarnsujarit, Sanguansri Charoenrein, and Yrjö H. Roos. The authors acknowledge Dr. Mark Auty, Moorepark Food Research Centre, Teagasc, Fermoy, Ireland for his expertise on the SEM imaging of freeze‐dried structures. p E315.     

Fatty acids and all‐trans‐β‐carotene are correlated in differently colored rice landraces

A set of 54 rice landrace samples was compiled from various Asian countries, including six red/brownish and eight black/purple varieties. Brown rice samples were analyzed for lipid content and fatty acid profile, as well as all‐trans‐β‐carotene content. Black/purple varieties were found to be higher in crude lipid content than the red/brownish and colorless varieties. They also had a higher β‐carotene content than the other two color classes. The highest β‐carotene content determined was 0.22 mg kg⁻¹. Black/purple varieties tended to have a higher proportion of saturated fatty acids in their lipid fraction and a lower proportion of unsaturated fatty acids. The differences were statistically significant (P < 0.05) for oleic acid, which accounted for 42.1% of the lipid fraction in black/purple varieties and for 45.3% and 46.3% in red/brownish and colorless varieties, respectively. β‐Carotene content showed a significantly positive correlation with the crude lipid content (P < 0.001) and the content of saturated fatty acids (P < 0.001) on a dry matter basis. However, it was not correlated with the unsaturated fatty acids content on a dry matter basis. Within the total lipid extract, β‐carotene showed a significantly positive correlation with the proportion of saturated fatty acids (P < 0.01), especially palmitic acid (P < 0.01), and a significantly negative correlation with unsaturated fatty acids (P < 0.001), especially oleic acid (P < 0.01). Copyright © 2005 Society of Chemical Industry     

State of dispersed lipid carrier and interface composition as determinants of beta-carotene stability in oil-in-water emulsions

Abstract: Liposoluble bioactive compounds are often included in foods in emulsified lipid carriers. In the present study, the impact of the physical state of the lipid carrier and the interfacial composition of oil‐in‐water emulsions on the stability of β‐carotene was studied. Emulsions with hydrogenated palm kernel oil (HPKO) concentration of 10% (w/w) dispersing 0.05% (w/w) β‐carotene, and a water phase at pH 7 containing 30% (w/w) sucrose, were stabilized by 1%, 1.5%, 2%, and 3% (w/w) whey protein isolate (WPI). Crystallization and melting behavior of emulsified and bulk HPKO were studied by differential scanning calorimetry. The hysteresis of emulsified HPKO crystallization (onset approximately 10 °C; endset approximately 6 °C) and melting (onset approximately 17 °C; endset approximately 45 °C) allowed us to operate at 15 °C on systems with identical compositions but different physical states of the same lipid phase. Surface protein coverage of emulsions was calculated and size of the dispersed particles was characterized by dynamic light scattering. β‐Carotene contents of the emulsions during storage at 15 °C was analyzed spectrophotometerically. Results highlighted an impact of the phase of the lipid carrier and of the concentration of WPI on β‐carotene degradation. β‐Carotene loss showed zero‐order kinetics. A liquid dispersed phase resulted in a low degradation rate but a high concentration of protein on a solid lipid carrier was likewise effective for β‐carotene protection. Practical Application: The inclusion of lipophilic bioactive compounds, such as carotenoids, is a current trend in the production of functional foods aiming to enhance health and well‐being. However, the use of functional ingredients in food products is complicated because of the sensitivity of the active molecules to physical and chemical factors to which they are exposed during processing, storage, and consumption. The present work gives indications of the influence of the lipid carrier physical state and surface structure on ß‐carotene stability in formulated oil‐in‐water liquid food models, suggesting possible strategies for an enhanced stabilization of lipophilic labile compounds.     

A proposed mechanism for the inhibition of soybean lipoxygenase by β‐carotene

The inhibition mechanism of soybean lipoxygenase (LOX) by β‐carotene was studied. Addition of β‐carotene into the reaction mixture decreased the rate of conjugated diene formation. Increasing the concentration of β‐carotene in the reaction mixture resulted in a decrease in the rate of conjugated diene formation. Although the rate of conjugated diene formation was lower in the presence of β‐carotene, the same amounts of linoleic acid hydroperoxides were formed by the enzyme at the end of the reaction, both with and without β‐carotene in the reaction medium. The rates of conjugated diene formation for 40, 20, 10 and 4 U mL^?1 LOX enzyme were almost equal to zero when the concentrations of β‐carotene were 20, 17.5, 15 and 10 µmol L^?1 in model reaction systems, respectively. β‐Carotene directly influences the amount of enzyme in the reaction medium available for the catalytic conversion of linoleic acid into corresponding hydroperoxides. The results obtained here suggest that β‐carotene reacts with linoleyl radical (L^?) at the beginning of the chain reaction, preventing the accumulation of conjugated diene forms (LOO^?, LOO^? and LOOH). Since L^? transforms back to its original form of LH, the enzyme cannot complete the chain reaction and thus remains at inactive Fe(II) form. Copyright © 2005 Society of Chemical Industry     

Effects of microwave and hot‐air drying methods on colour, β‐carotene and radical scavenging activity of apricots

The effects of drying by microwave and convective heating at 60 and 70 °C on colour change, degradation of β‐carotene and the 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH) scavenging activity of apricots were evaluated. Microwave heating reduced significantly the drying time (up to 25%), if compared with convective one, also owing to the higher temperature reached during the last phase of the process, as monitored by infrared thermography. Colour changes of apricot surface, described with lightness and hue angle, in both drying methods followed a first‐order reaction (0.927 ≤ R² ≤ 0.996). The apricots dried by microwave were less affected by the darkening phenomena. The evolution of β‐carotene in fresh apricots (61.2 ± 5.6 mg kg^?1 d.w.) during the drying highlighted a wider decrease (about 50%) when microwave heating was employed for both the temperatures used. Radical scavenging activity increased (P < 0.05) in all dried samples except for hot‐air dried apricots at 60 °C.     

β‐Carotene as a Membrane Antioxidant Probed by Cholesterol‐Anchored Daidzein

β‐Carotene is found to be more effective as an antioxidant in phosphatidylcholine (PC) liposomes when protecting against hydrophilic radicals compared to lipophilic radicals, as measured by the rate of formation of conjugated dienes. Daidzein alone is without effect, but decreases the antioxidative effect of β‐carotene for hydrophilic initiation and increases the effect for lipophilic initiation. The newly synthesized 7‐cholesterylglycol daidzein has the opposite effect for β‐carotene as antioxidant, with a strong enhancement for hydrophilic initiation and a slight decrease for lipophilic initiation. Redistributing β‐carotene to membrane surfaces by cholesterol‐anchoring of daidzein enhances protection against aqueous radicals significantly at the expense of protection against lipid‐derived radicals. Anchoring of daidzein to cholesterol is concluded to be useful as a mechanistic tool for controlling antioxidant distribution in membranes sensitive to radical damage, as supported by quantum mechanical calculation within the density function theory and further supported by fluorescence probes and fluorescence polarization probes.     

Drying Kinetics and β-Carotene Degradation in Carrot Undergoing Different Drying Processes

Superheated steam drying, which is an airless drying technology, has recently received much attention as an alternative to conventional hot air drying, which is a relatively oxygen‐rich drying process and causes much product quality degradation. However, because most food products are damaged when subjected to superheated steam at atmospheric or higher pressures, lowering the dryer operating pressure is preferred. In this study, the effects of a low‐pressure superheated steam drying (LPSSD), vacuum drying, and hot air drying on the drying and degradation kinetics of β‐carotene in carrot were investigated experimentally. LPSSD and vacuum drying led to less degradation of β‐carotene in carrot than in the case of hot air drying. The empirical models, which can describe the experimental data of β‐carotene degradation in carrot undergoing different drying techniques, were also proposed. β‐Carotene degradation in carrot depended more on the carrot temperature than its moisture content in all cases.     

Effect of polyglycerol esters of fatty acids on physicochemical properties and stability of β‐carotene nanodispersions prepared by emulsification/evaporation method

The effects of six different polyglycerol esters of fatty acids (PGEs) as nonionic emulsifiers on the physicochemical properties and stability of β‐carotene nanoparticles in oil‐in‐water dispersions produced by an emulsification/evaporation technique were examined. The β‐carotene particle size was measured by a laser diffraction technique, and the stability and retention of β‐carotene during various preparation steps and storage were determined by HPLC. In the prepared nanodispersions the β‐carotene particle size decreased with increasing degree of glycerol polymerisation and decreasing carbon number of the fatty acid group in the PGE. The particle size of β‐carotene in nanodispersions containing polyglycerol monooleate was generally larger than that in the presence of polyglycerol monolaurate. During storage at 4 °C, although the β‐carotene content in the nanodispersions showed a significant ( P < 0.05) decrease with increasing storage period, the size distribution of β‐carotene was almost unchanged in all prepared nanodispersions. In general, the mean diameter of β‐carotene nanoparticles ranged from 85 to 132 nm. In the light of their ability to physically stabilise β‐carotene particle formation, it is suggested that PGEs with a high degree of glycerol polymerisation may be useful in the preparation of β‐carotene nanodispersions. The best stabilisation was obtained using 10 g kg^?1 decaglycerol monolaurate. Copyright © 2004 Society of Chemical Industry     

Optimisation of drying conditions for the extraction of β‐carotene,phenolic and ascorbic acid content from yellow‐fleshed sweet potato using response surface methodology

The objective of this study was to optimise drying conditions for the extractions of β‐carotene, phenolic and ascorbic content from yellow‐fleshed sweet potato using response surface methodology. A face‐centred cubic was used to investigate the effects of three independent variables namely drying temperature 55–65 °C, citric acid concentration 1–3%w/v and soaking time 1–3 min. The optimal conditions for parameters were 55–62 °C, citric acid concentration 1.08–2.19% and soaking time 1.53–2.00 min. Under the above mentioned conditions, the experimental β‐carotene content was 14.61 mg g^?1, total phenolic and ascorbic acid content were 4.0 and 17.53 mg g^?1, respectively, which were close to the predicted values. Therefore, the results showed that optimise conditions could be used to enhance the antioxidant activities of functional foods.     

Degradation of β-carotene in amorphous polymer matrices. Effect of water sorption properties and physical state

BACKGROUND: The use of encapsulation in amorphous matrices of carbohydrate and/or polymer formed during dehydration processes to enhance the stability and retention of labile compounds is increasing in the food and pharmaceutical industries. Efforts to improve encapsulating properties have been made using mixtures of carbohydrates with proteins or gums in different proportions. The objective of the present work was to study the stability of encapsulated β‐carotene and its degradation kinetics in maltodextrin/gum arabic and maltodextrin/gelatin matrices in relation to the physical properties and state of the dehydrated matrix. RESULTS: The degradation of β‐carotene followed a first‐order kinetic model of fractional retention for all encapsulating matrices. The Guggenheim–Anderson–de Boer (GAB) model was adequate to describe the sorption isotherms of the studied systems. β‐Carotene losses were observed mainly at relative humidities (RHs) above the glass transition temperatures (T_g) of the corresponding systems, where the matrices were fully plasticised and collapsed (75 and 92% RH). At these high RHs the best β‐carotene retention was obtained in the system containing gum arabic. CONCLUSION: The results showed that pigment degradation was determined by the physical state of the matrix, related to the degree of collapse. They represent a contribution to the knowledge of physical factors that affect the retention kinetics of labile biomolecules encapsulated in dehydrated matrices. Copyright © 2011 Society of Chemical Industry     

Provitamin‐A and xanthophyll carotenoids in vegetables and food grains of nutritional and medicinal importance

This study reports carotenoid composition of vegetables (n = 56), cereals (n = 12), pulses and legumes (n = 12), analysed by HPLC. It was hypothesised that food grains, like vegetables may be good sources of carotenoids. Amongst vegetables, higher level (mg/100 g dry weight) of lutein (210–419) was detected in green/red/capsicum and yellow zucchini, whilst zeaxanthin was dominant in kenaf (4.59). β‐Carotene (mg/100 g dry weight) was higher in green capsicum and kenaf (48,159) whilst carrot, ivy gourd and green capsicum contain α‐carotene (22–110). Amongst food grains, chickpea, split red gram and flaxseed contain higher levels (μg/100 g dry weight) of lutein (185–200) whilst zeaxanthin level was highest in puffed chickpea (1.8). Red unpolished parboiled rice was richest (μg/100 g dry weight) in β‐carotene (67.6) whilst whole black gram contained higher levels of α‐carotene (52.7). Thus, results indicate that chickpea and red unpolished parboiled rice are good sources of carotenoids. These carotenoid‐rich vegetables and grains may be exploited to meet the lutein and β‐carotene requirement.     

Stability of protein‐stabilised β‐carotene nanodispersions against heating,salts and pH

BACKGROUND: Milk proteins are used in a wide range of formulated food emulsions. The stability of food emulsions depends on their ingredients and processing conditions. In this work, β‐carotene nanodispersions were prepared with selected milk‐protein products using solvent‐displacement method. The objective of this work was to evaluate the stability of these nanodispersions against heating, salts and pH. RESULTS: Sodium caseinate (SC)‐stabilised nanodispersions possessed the smallest mean particle size of 17 nm, while those prepared with whey‐protein products resulted in larger mean particle sizes (45–127 nm). Formation of large particles (mean particle size of 300 nm) started after 1 h of heating at 60 °C in nanodispersions prepared with SC. More drastic particle size changes were observed in nanodispersions prepared with whey protein concentrate and whey protein isolate. The SC‐stabilised nanodispersions were fairly stable against Na⁺ ions at concentrations below 100 mmol L^?1, but drastic aggregation occurred in ≥ 50 mmol L^?1 CaCl₂ solutions. Aggregation was also observed in whey protein‐stabilised nanodispersions after the addition of NaCl and CaCl₂ solutions. All sample exhibited the smallest mean particle size at neutral pH, but large aggregates were formed at both ends of extreme pH and at pH around the isoelectric point of the proteins. CONCLUSION: The nanodispersions prepared with SC were generally more stable against thermal processing, ionic strength and pH, compared to those prepared with whey proteins. The stable β‐carotene nanodispersions showed a good potential for industrial applications. Copyright © 2008 Society of Chemical Industry     

Effects of Heat Treatment on the Carotenoid and Tocopherol Composition of Tomato

Abstract: The objective of this study was to determine the influence of thermal processing on the assessment of tocopherols and carotenoids, as well as their isomer formation in tomatoes. The sliced tomatoes were heated in an oven at 100, 130, and 160 °C for 5, 10, and 20 min, then freeze‐dried. Freeze‐dried samples were finely ground and the analysis was performed on lyophilized samples. The average concentrations of total lycopene, lutein, β‐carotene, α‐tocopherol, and γ‐tocopherol in fresh tomatoes (in 100 g dry weight) were 21.2, 1.1, 2.7, 8.0, and 2.5 mg, respectively. Oven baking of tomato at 160 °C for 20 min led to a significant increase in the apparent measurement of lycopene, β‐carotene, and α‐tocopherol content by 75%, 81%, and 32%, respectively. Heating induced isomerization of (all‐E) to various (Z) isomers of lycopene, and we found that the total (Z)‐lycopene proportion in the tomatoes increased with longer heating time. (All‐E)‐lycopene constituted 75.4% in fresh tomatoes and decreased to 52.5% in oven‐baked tomatoes (160 °C, 20 min), while (5Z)‐lycopene increased from 9.4% to 17.9% of total lycopene. However, β‐carotene release and isomerization was less influenced by the heat treatment than that of lycopene. These results suggested that thermal processes might break down cell walls and enhance the release of carotenoids and tocopherols from the matrix, as well as increase isomerization of lycopene and β‐carotene.     

Vitamin E levels,thiobarbituric acid test and sensory evaluation of breast muscles from broilers fed α‐tocopheryl acetate‐ and β‐carotene‐supplemented diets

The objective of this study was to investigate the effect of dietary α‐tocopheryl acetate and β‐carotene supplementation on lipid oxidation of breast meat from broilers fed lard as the fat source. Supplementation of broilers with 100 mg kg^?1 α‐tocopheryl acetate increased the vitamin E levels in raw breast samples significantly (p < 0.05), whereas the presence of 1.5 mg kg^?1 dietary β‐carotene tended to decrease vitamin E deposition. The presence of vitamin E delayed lipid oxidation significantly, but thiobarbituric acid values of samples from broilers fed the β‐carotene‐supplemented diet did not differ from those of control samples. Vitamin E reduced sensory meat rancidity, whilst vitamin E, β‐carotene and their combination modified meat texture. The results show the effectiveness of dietary α‐tocopheryl acetate supplementation in protecting broiler meat against lipid oxidation. Copyright © 2004 Society of Chemical Industry     

Bioactive compounds and antioxidant potential in fresh and dried Jaffa® sweeties,a new kind of citrus fruit

Bioactive compounds in the edible parts of fresh and dried Jaffa^® sweeties, a new kind of citrus fruit, were analysed and their antioxidant capacities were assessed. Antioxidant‐rich fractions were extracted from fresh and dried sweeties with 1.2 M HCl in methanol/water (1:1 v/v), and the antioxidant activities of these extracts were evaluated. Using the β‐carotene/linoleate model system, the extracts from equivalent quantities of fresh and dried sweeties showed 89 and 87% antioxidant activity respectively. Similarly, using the DPPH radical‐scavenging method, the extracts showed 87 and 85% antioxidant activity respectively. The best correlations were between caffeic acid content and β‐carotene and DPPH antioxidant activity values (r = 0.9849 and 0.9798 respectively, p = 0.005). Both fresh and dried sweeties are bioactive natural products; when fresh fruits are not available, properly dried sweeties could be used as a substitute. Copyright © 2004 Society of Chemical Industry