Lipid oxidation in glassy and rubbery-state starch extrudates

This work describes the principle of protecting polyunsaturated fatty acids by holding them in the low moisture/solid/glassy-state starch matrix. One strategy already employed commercially is to encapsulate oil droplets within a solid wall that is highly impermeable to oxygen. These microencapsulated powders can then be added to foods. A shorter route would be to add PUFA-rich oils directly into a food formulation during the processing of a low moisture product. This should effectively encapsulate the valuable oils and protect them from oxidation. ω-6 Linoleic acid was incorporated into a waxy maize starch matrix via extrusion cooking. Linoleic acid oxidation occurred when this model food system was held in both the glassy and rubbery states (0.3 and 0.95 Aw, respectively) at 50 °C. The initial oxidation, not surprisingly, occurs near the surface, but interestingly the highest initial rate of lipid oxidation occurred, not in the rubbery samples, but in glassy state starch extrudates with surface micro-cracks.     

Influence of relative humidity on oxidation of the free and encapsulated oil fractions in freeze-dried microencapsulated oils

The objective of this work was to evaluate the effect of relative humidity (RH) on oxidation of the free and encapsulated oil fractions of dried microencapsulated oils (DMOs) during long-term storage at 30 °C. Sunflower and fish oils with different tocopherol content were encapsulated in a milk-based encapsulation matrix. The total non-volatile oxidation products and tocopherol were quantitated. Results showed that 0% and 32% RH were, respectively, the most unfavourable and favourable conditions against lipid oxidation. The 32% RH atmosphere exerted a great protective effect on the free oil as compared to 0% RH, while no or a negligible effect was found in the encapsulated oil. Except for the samples most susceptible to oxidation, the free oil remarkably oxidized more slowly than the encapsulated oil regardless of RH. Therefore, there were factors other than moisture that determined the oxidation rate in the free and encapsulated fractions of the DMOs.     

Effect of total solids content in feed emulsion on the physical properties and oxidative stability of microencapsulated kenaf seed oil

Kenaf (Hibiscus cannabinus L.) seed oil has high potential to be used as edible oil. Despite the high content of polyunsaturated fatty acids, one of the major complications in commercialisation kenaf seed oil is its rapid oxidation, which leads to the production of undesirable toxic substances such as peroxides. The objective of this study was to investigate the effect of total solids content (TSC) on the oxidative stability of microencapsulated kenaf seed oil (MKSO) and to compare its oxidative stability with bulk kenaf seed oil upon accelerated storage. Microcapsules with 20%, 30% and 40% total solids content were prepared. Physical properties, such as the emulsion characteristics and microcapsules characteristics were also studied. Results showed that bulk kenaf seed oil was oxidised to a greater extent compared to the microencapsulated samples. The results showed that 40% total solids content microcapsules had the lowest peroxide value (PV), p-anisidine value (AnV), total oxidation (TOTOX) value and free fatty acid (FFA) value, which were 3.70 ± 0.83 meq O₂/kg oil, 16.12 ± 0.19, 23.52 ± 1.67 and 2.54 ± 0.06%, respectively. The microencapsulation of kenaf seed oil showed protective effect against lipid oxidation.     

Stability of Crude Herring Oil Produced from Fresh Byproducts: Influence of Temperature during Storage

ABSTRACT: Crude herring oil, extracted from fresh byproducts, was stored at 0, 20, and 50°C in order to study the effect of temperature on lipid oxidation. The oil had an initial peroxide value (PV), anisidine value (AV), and free fatty acids of 0.7 meq peroxides/kg of lipid, 0.4, and 0.6%, respectively. During storage, the oil reached the secondary oxidation stage for all 3 temperatures. The formation of fluorescent compounds was inhibited at 0°C. Significant decrease of the α-tocopherol content was found after storage at 0 and 20°C, but no consumption occurred at 50°C. The development of oxidation products over time exhibited a temperature-dependency with a very good correlation.     

响应面试验优化盐焗鸡卤汁分离鸡油微胶囊化工艺

以辛烯基琥珀酸淀粉钠和麦芽糊精为复合壁材对精炼过后的鸡油进行喷雾制作微胶囊鸡油。通过响应面分析法获得最佳微胶囊制作工艺条件为进风温度190 ℃、均质压力39 MPa、进样速率15 mL/min,最终微胶囊鸡油产品包埋率为95.9%。微胶囊鸡油呈规则球状,表明较光滑,减少了与外界接触的机会,减慢了氧化速率。产品经（60±1）℃加速氧化5 d后,过氧化值仅为对照样品的1/3,抗氧化效果明显。     

Encapsulation and Oxidative Stability of PUFA-Rich Oil Microencapsulated by Spray Drying Using Pea Protein and Pectin

This study aimed at evaluating the potential of pectin combination with pea protein isolate (PPI) in the microencapsulation of polyunsaturated fatty acids (PUFA)-rich oil by spray drying, in order to maximize encapsulation efficiency and minimize lipid oxidation. The feed emulsions used for particle production consisted of PUFA-rich oil droplets coated by either PPI (primary emulsion) or PPI–pectin (secondary emulsion). Dry emulsions characteristics and oxidative stability of microencapsulated oil as a function of relative humidity (RH; from 11 % to 75 %) were determined. Scanning electron microscopy (SEM) images revealed considerable structural changes. Oil droplets retained their shape upon drying and reconstitution. However, a shift in oil droplet size upon reconstitution indicated that oil droplet coalescence occurred within the process. Oxidation of microencapsulated oil in secondary emulsion was delayed from that of primary emulsion but followed the same pattern with regards to humidity. A high rate of oxidation was found for intermediate RH conditions (33 % and 57 % RH). The lowest rate of oxidation as followed by hydroperoxide and thiobarbituric acid reactive substances values was found at 75 % RH, a condition that is likely to diverge significantly from the monolayer moisture value. The oxidative stability of encapsulated oil was influenced by both physical state of the emulsions and the different constituents at the oil-in-water interface with PPI–pectin secondary emulsion giving the best protection of the oil.     

Vitamin E and Oxidative Stability During Storage of Raw and Dry Roasted Peanuts Packaged under Air and Vacuum

ABSTRACT: The relationship between vitamin E and the oxidative stability of raw and dry roasted peanuts was studied during storage at 21°C under air and vacuum. Lipid oxidation was monitored by peroxide values (PVs) and conjugated diene values (CDVs). In air, PV (meq/kg) for roasted peanuts reached 47 by 12 wk, whereas that for raw peanuts was below 2 after 38 wk. Under vacuum, lipid oxidation was significantly retarded ( P < 0.05). Tocopherols of raw and roasted peanuts exponentially decreased with increasing PV. After 12 wk, about 50% of α-tocopherol (α-T) was lost for roasted peanuts under vacuum compared with about 90% under air. For raw peanuts, more than 70% of each tocopherol remained after 38 wk under air and vacuum. In general, α-T showed the least stability in roasted peanuts compared with other tocopherols under the reported storage conditions.     

Effect of black tea, garlic and onion on corn oil stability and fatty acid composition under accelerated oxidation

Fresh black tea, garlic bulbs and onion skin were macerated in refined corn oil to evaluate their antioxidant properties and the effect of heat on oil stability and fatty acid composition in accelerated oxidation experiments at 55 ° and 140 °C. At the lowest temperature control and onion treatments showed an induction time of 3 days with maximum peroxide values of 62 and 45 meq kg^?1, respectively. Addition of black tea and garlic increased oil stability with peroxide values of 5 meq kg^?1, without appreciable changes in the fatty acid composition. Heating at 140 °C for 48 h produced an accelerated deterioration of corn oil in all treatments. A reduction of polyunsaturated fatty acids of about 40% was observed, with high concentrations of non‐eluted materials which contained thermo‐oxidized substances. It was found that natural extract of black tea and garlic were effective to preserve corn oil under accelerated oxidation at 55 °C which simulates oil behaviour during storage, but cannot reduce the rate of oxidation at frying temperatures.     

Effects of Blueberry (Vaccinium corymbosum) Juice on Lipid Oxidation During Spray Drying of Microencapsulated Menhaden Oil

This study investigated the effect of blueberry juice on menhaden oil lipid oxidation during microencapsulation. Oil in water emulsions containing menhaden oil with 0, 5, or 10% blueberry juice were spray dried to produce control-M, 5% BJ-M, and 10% BJ-M microencapsulated powders, respectively. All microencapsulated powders had similar encapsulation efficiencies with low surface oil content. Peroxide value (meq/kg of oil) was 4.50, 4.31, and 3.38 for control-M, 5% BJ-M and 10% BJ-M, respectively. Ten percent BJ-M had lower (P < 0.05) anisidine value, and totox values than 5% BJ-M and control-M. This indicated that 10% blueberry juice reduced lipid oxidation in menhaden oil during microencapsulation to a greater extent than the other formulations.     

Spray‐drying encapsulation of citral in sucrose or trehalose matrices: physicochemical and sensory characteristics

The potential of the disaccharide trehalose as carrier for producing spray‐dried citral was examined. Some physical and sensory characteristics of citral encapsulated in matrices containing either trehalose or sucrose and maltodextrin (MD) were analysed. They included water sorption, glass transition temperatures (T_g), nuclear magnetic resonance (NMR) relaxation and citral retention during spray‐drying. The glassy state at room temperature (25 °C) was maintained as far as 33% relative humidities (RH) for the spray‐dried trehalose formulation and 43% RH for trehalose–MD; however, for sucrose–MD and for sucrose formulations, the glassy state was limited to RHs lower than 33% and 22%, respectively. Sensory evaluation and gas chromatographic analysis indicated that citral retention after spray‐drying was similar for matrices containing either trehalose or sucrose. However, trehalose formulations had improved physical stability as compared to sucrose.     

Interconversions of Isoflavones in Soybeans as Affected by Storage

ABSTRACT: Conversions of isoflavones in soybeans under 4 conditions were investigated. Soybeans were stored in 84% RH, 30 °C for 9 mo and in 57% RH, 20 °C, cold (4 °C), and an uncontrolled ambient garage for 18 mo. Isoflavones were analyzed by HPLC. In 84% RH, 30 °C, the interconversion between aglycones and β-glucosides was significant ( p < 0.001). The percentage of β-glucosides and malonylglucosides in total isoflavones decreased from 99% to 3% in 9 mo. In contrast, the aglycones increased from 1% to 97%. In 57% RH, 20 °C, and ambient conditions, the glucoside forms increased with storage time, but malonylglucosides tend to decrease. In the 4 °C condition, isoflavone distribution had no significant ( p > 0.05) changes during storage.     

Enhanced survival of spray-dried microencapsulated Lactobacillus rhamnosus GG in the presence of glucose

The survival of spray dried Lactobacillus rhamnosus GG (LGG) preparations encapsulated in whey protein isolate (WPI)-maltodextrin, WPI-maltodextrin-glucose, WPI-inulin, and WPI-inulin-glucose mixtures during storage at 25 °C (11%, 57% and 70% relative humidity, RH) was examined. The glass transition temperature of each encapsulant formulation was also assessed. RH was most important for maintaining viability over time; the inclusion of glucose improved viability, irrespective of when all formulations were in a glassy or rubbery state. When LGG microcapsule powders were stored at the same RH, the addition of glucose in the encapsulant formulation had a greater influence on survival of LGG during storage than the maintenance of a glassy state. Both the maintenance of a glassy state during storage and the incorporation of glucose in the encapsulant formulation were required for optimal survival of probiotic microcapsule powders prepared from fresh cultures.

Practical significance

The incorporation of glucose into the encapsulant formulation prior to spray drying of protein-carbohydrate based LGG formulations improves the survival of LGG during long term storage.     

Water sorption and the plasticization effect in wafers

Wafers are low moisture food products whose crunchiness or crispness is considered a primary textural attribute, highly affected by the product's physical state (glassy or rubbery). The water activity–water content–glass transition relationships for commercial wafers are reported, using Gordon and Taylor's equation to model the water plasticization effect and also Brunnaver‐Emmett‐Teller (BET) and Guggenheim‐Anderson‐DeBoer (GAB) sorption models. BET monolayer moisture content was 6.2% and the moisture limit to fit this model was about 11.5%. Critical water activity and critical water content for the glass transition of the product at 20 °C were 0.591 and 0.118 (mass fraction) respectively. Abrupt changes in the mechanical product properties, evaluated from a three‐point bend test, could be observed at these limits. Moisture levels between 6 and 11% give rise to a glassy state matrix in the product and so to acceptable product crispness. Below this range, the glassy matrix seems to turn fragile and, above this range, the product becomes rubbery.     

Temperature-dependence of rate of oxidation of rapeseed oil encapsulated in a glassy food matrix

Oxidation of stripped rapeseed oil, encapsulated in a carbohydrate/protein glassy matrix, initiated by a lipophilic free radical initiator (or not initiated) and monitored as peroxide value and conjugated dienes for 45 days, developed differently depending on storage temperature. At low temperature (5 °C), the encapsulated oil and bulk oil, as reference, showed little oxidation which, moreover, could be accounted for by the oxygen dissolved in the oil. At intermediate temperatures (25 and 45 °C), oxidation exceeded the level corresponding to dissolved oxygen and became dependent on oxygen transport through the matrix. At high temperature (60 °C), a rapid, linear increase in peroxide concentration was followed by an autocatalytic phase with a rapid increase in peroxides, subsequently reaching a steady-state concentration. The oxidation of the encapsulated oil was found to have a lower energy of activation (around 60 kJ/mol) than the bulk oil (around 80 kJ/mol), resulting in a protection of the encapsulated oil at higher temperatures. However, the temperature-dependence of the zeroth order rate constants for initial peroxide formation in the encapsulated oil showed a shift from a rate determining reaction at low temperature with a high energy of activation to a reaction at higher temperature with a smaller energy of activation, especially for the encapsulated oil without initiator added. At low temperature, lipid oxidation seems rate-determining while, at higher temperature, oxygen permeation through the matrix with a lower energy of activation becomes rate-determining. The glassy matrix yields only partly protection against lipid oxidation as it allows permeation of oxygen and other small molecules, as further confirmed by the effect of a hydrophilic radical initiator, incorporated in the matrix, on peroxide value of the encapsulated oil.     

Process engineering parameters and type of n-octenylsuccinate-derivatised starch affect oxidative stability of microencapsulated long chain polyunsaturated fatty acids

Aim of the present study was to investigate the impact of the emulsifying carrier matrix constituent, n-octenylsuccinate-derivatised (OSA)-starch, and process conditions on physical characteristics and oxidative stability of microencapsulated fish oil. Furthermore, the effect of the drying medium, i.e. air or nitrogen, on lipid oxidation during spray-drying and subsequent storage was investigated. Particle characteristics and lipid oxidation of microencapsulated fish oil were both influenced by the type of OSA-starch and the drying conditions. The highest oxidative stability was observed for fish oil microencapsulated in OSA-starch with the lowest average molecular weight and glucose syrup spray-dried at a moderate temperature setting. Particle characteristics of the microcapsules were not attributable for differences in lipid oxidation during storage. In spray-dried carrier matrix particles, the particle size increased with increasing average molecular weight of the OSA-starch and was attributed to an increase in air inclusion. Thus differences in lipid oxidation of the microencapsulated fish oil were attributed to differences in air inclusion as affected by the type of OSA-starch. In terms of spray-drying under inert conditions and in the presence of air, lipid oxidation of microencapsulated fish oil was rather attributed to oxygen availability in the feed emulsion than in the drying gas.     

Effect of Water Activity on the Stability to Oxidation of Spray-Dried Encapsulated Orange Peel Oil Using Mesquite Gum (Prosopis Juliflora) as Wall Material

ABSTRACT: Mesquite gum solutions (30% w/v) were used to emulsify orange peel oil in an oil-gum solids ratio of 0.25. Emulsions were spray dried in laboratory scale equipment. The powders were stored in a_w (s) from 0.108 to 0.743 at 35 °C. Quantitative analysis of limonene oxide indicated that the sample at 0.628 showed a very good stability against oxidation after thirty d, without caking and stickiness occurring. At this water activity the system was within rubbery state, and the moisture content corresponded to that of the minimum integral entropy.     

INFLUENCE OF TEMPERATURE AND RELATIVE HUMIDITY ON THE PHYSICAL STATES OF COTTON CANDY

Cotton candy is made by melting crystalline sucrose above 210C in a bowl which shoots molten liquid sucrose into the air where it rapidly cools and dries into an amorphous glassy solid state. As such, it is highly hygroscopic, picking up moisture as %RH increases and becoming rubbery. The glass transition line (T_g vs. %RH) divides the two states. When rubbery, cotton candy should collapse forming crystalline sucrose becoming unsaleable. Cotton candy was stored at 25C and at %RH from ～0% to 75%. Moisture gain/loss, visual observations, and powder X‐ray diffraction using a Seimens 5005‐powder X‐ray diffractometer were used to evaluate collapse and crystallization. At ～0% and 11% RH (below T_g), cotton candy maintained a stable structure for at least 12 months. At 33% RH (just at T_g), it collapsed and crystallized within 3 days while at 45, 54 and 75% RH, collapse and crystallization occurred in less than 1 day.     

茶籽油微胶囊的制备及其产品特性研究

采用喷雾干燥法制备茶籽油微胶囊粉末油脂,并对产品配方和啧雾干燥工艺参数进行优化,同时系统分析产品的理化性质、稳定性和体外释放特性.结果 表明,最佳配方为麦芽糊精/大豆分离蛋白/阿拉伯胶质量比为1:1.5:1.5,芯材/壁材质量比为1:1.5,乳化液固形物质量分数为20％;喷雾干燥加热温度为180℃,进料泵速25 r/m...     

Physicochemical characterization and oxidative stability of fish oil encapsulated in an amorphous matrix containing trehalose

Fish oil with 33% omega-3 fatty acids was microencapsulated by spray-drying in a matrix of n-octenylsuccinate-derivatized starch and either glucose syrup or trehalose. Samples showed no difference in physicochemical properties as determined by measurement of particle size, oil droplet size, true density and BET surface. Upon storage at low relative humidity, lipid oxidation was decreased in trehalose containing samples indicating that in the amorphous state trehalose is a more suitable wall material for microencapsulation than glucose syrup. The retarded oxidation of trehalose containing samples may be attributed to the unique binding properties of trehalose to dienes. At 54% relative humidity, a rapid oxidation of the microencapsulated oil was observed upon crystallization of trehalose, which limits the range of applications to products to be stored at low humidity.     

Microencapsulation of linseed oil by spray drying for functional food application

Health benefits associated to ω-3 fatty acids consumption together with the high susceptibility to oxidation of ω-3 containing oils have led to the development of microencapsulated oils for nutraceutical and food enrichment applications. The aim of this work is to obtain different formulations for linseed oil microencapsulation by spray-drying with high encapsulation efficiency and evaluate their resistance to oxidation through the accelerated Rancimat test. Four formulations were tested; using different combinations of gum arabic (GA), maltodextrin (MD), methyl cellulose (MC) and whey protein isolate (WPI). Microcapsules made of 100% GA and ternary mixtures of GA, MD and WPI presented the highest protection from oxidation and microencapsulation efficiencies higher than 90%. They also presented spherical structures with smooth surfaces which kept unaltered after 10-month storage. GA containing formulation was included in bread manufacturing. Fortified bread resulted similar in appearance to control bread without microcapsules, but α-linolenic acid content was reduced significantly after preparation.