Crystallization behavior of lactose/sucrose mixtures during water-induced crystallization

The crystallization behavior of lactose/sucrose mixtures during water-induced crystallization was studied to gain more insight about their crystallization during storage. Solutions with different ratios of lactose and sucrose, 75:25 and 50:50, were spray dried to produce amorphous powders. The powders were kept at a controlled temperature and humidity to study their sorption–desorption behavior. X-ray diffraction and light microscopy analysis were performed to study their crystallization behavior. Two-step desorption was observed after sieving the powders as sample preparation. Sieving decreased the crystallization time for lactose/sucrose mixture 75:25 from 22 days to 2.5 days. Based on the X-ray diffraction analysis during this two-step process of water desorption, it was concluded that lactose crystallizes first and more quickly than sucrose. The degree of crystallization for the lactose crystals increases by 89% (relative to their final level of crystallinity), whereas sucrose crystals increase their level of crystallinity by only 28% during the first step of crystallization in the lactose/sucrose (75:25) mixtures. The light microscopy images also suggested that the crystallization of amorphous lactose/sucrose powders during water-induced crystallization may occur as a solution rather than in the solid phase.     

Lipid and water crystallization in protein-stabilised oil-in-water emulsions

Phase and state transitions occurring during freezing and thawing of oil-in-water emulsions with different water phase formulations, interfacial compositions and two lipid types were studied as crucial factors affecting emulsion stability. Emulsions containing 0–40% (w/w) sucrose in the water phase at pH 7, and 10, 20, 30, 40% (w/w) dispersed lipid phase (sunflower oil, SO or hydrogenated palm kernel oil, HPKO) with whey protein isolate, WPI, or sodium caseinate, NaCAS, (protein:lipid = 1:10 and 2:10) as emulsifier were prepared. Phase/state behaviour of the continuous and dispersed phases was determined by differential scanning calorimetry (DSC). Emulsion stability and morphology were derived from DSC data, gravitational separation and particle size analysis during 4 freeze-thaw cycles. Systems were stable when only lipid crystallization occurred. DSC data showed that lipid crystallization prior to water crystallization (i.e. emulsions containing HPKO) caused destabilisation at low sucrose concentrations (0, 2.5 and 5% w/w). Emulsions were stable if the dispersed oil phase crystallized after the dispersing water phase (i.e. emulsions containing SO). A concentration of sucrose ≥10% (w/w) in the aqueous phase gave stable emulsions. At 10:1 lipid to protein ratio, WPI showed better stabilising properties than NaCAS at 2.5 and 5% (w/w) sucrose. Double concentration of WPI (lipid:protein = 10:2) at 0% (w/w) sucrose significantly improved systems stability, whereas no positive effect was observed when the concentration of NaCAS was increased. From morphology study, in addition to lipid destabilisation, thickening and flocculation caused instability of the systems. These were extensive in systems containing WPI and were ascribed to interactions between whey proteins during thermal cycling.     

Stability and Oil Migration of Oil‐in‐Water Emulsions Emulsified by Phase‐Separating Biopolymer Mixtures

Oil‐in‐water (O/W) emulsions with varying concentration of oil phase, medium‐chain triglyceride (MCT), were prepared using phase‐separating gum arabic (GA)/sugar beet pectin (SBP) mixture as an emulsifier. Stability of the emulsions including emulsion phase separation, droplet size change, and oil migration were investigated by means of visual observation, droplet size analysis, oil partition analysis, backscattering of light, and interfacial tension measurement. It was found that in the emulsions prepared with 4.0% GA/1.0% SBP, when the concentration of MCT was greater than 2.0%, emulsion phase separation was not observed and the emulsions were stable with droplet size unchanged during storage. This result proves the emulsification ability of phase‐separating biopolymer mixtures and their potential usage as emulsifiers to prepare O/W emulsion. However, when the concentration of MCT was equal or less than 2.0%, emulsion phase separation occurred after preparation resulting in an upper SBP‐rich phase and a lower GA‐rich phase. The droplet size increased in the upper phase whereas decreased slightly in the lower phase with time, compared to the freshly prepared emulsions. During storage, the oil droplets exhibited a complex migration process: first moving to the SBP‐rich phase, then to the GA‐rich phase and finally gathering at the interface between the two phases. The mechanisms of the emulsion stability and oil migration in the phase‐separated emulsions were discussed.     

Mechanical,Thermal, and Interfacial Characterization of Randomly Oriented Short Sisal Fibers Reinforced Epoxy Composite Modified with Epoxidized Soybean Oil

Short sisal fibers were reinforced in epoxidized soybean oil (ESO) modified toughened epoxy blends to improve the mechanical and thermo mechanical properties. Tensile modulus and tensile strength of the composite with 15 wt% sisal fiber were found to be increased as compared with bio-based epoxy blend. From DTG analysis, rate of degradation peak is found to be shifted to higher temperature revealing enhanced thermal stability of composite over base matrix. Dynamic mechanical analysis predicted higher storage modulus and higher glass transition temperature of bio-based epoxy composite. Scanning electron micrographs showed strong fiber-matrix adhesion. Contact angle measurement reveals the hydrophilic character of bio-based epoxy composite     

Microstructure and color of starch–gum films: Effect of gum deacetylation and additives. Part 2

Xanthan gum deacetylation, additives (sucrose, soybean oil, sodium phosphate and propylene glycol) and pH modifications influence on cassava starch-based films microstructure and color has been studied. X-ray diffraction and microscopic analysis have demonstrated that sucrose addition influenced (p<0.05) the film crystallinity during 60 days storage (75% RH, 23 °C). Although not enough to prevent sucrose crystallization, deacetylated xanthan gum addition delayed the crystallization process. Comparing to the control, only cassava starch concentration and the additives sucrose and sodium phosphate affected samples total color difference (ΔE). However, all samples presented high lightness and low color values for ‘a’ redness and ‘b’ yellowness, indicating that, independent of the additives or pH modifications, the materials were almost colorless, with a high brilliancy.     

Influence of SFC, microstructure and polymorphism on texture (hardness) of binary blends of fats involved in the preparation of industrial shortenings

Several binary blends of vegetable oils commonly used in industrial shortenings (i.e., palm oil (PO), hydrogenated palm oil (HPO), soybean oil (SO), hydrogenated soybean oil (HSO), low-erucic acid rapeseed oil (LERO), hydrogenated low-erucic acid rapeseed oil (HLERO)) were studied for their physical properties such as solid fat content (SFC) by nuclear magnetic resonance (NMR) and textural properties (hardness). Microstructure was also observed by microscopy in order to explain the variability in hardness for samples having the same SFC values. The blends studied by microscopy were the following: HSO, HPO and HLERO diluted in LERO. For these three blends which had the same SFC, the level of network structure was different. HSO diluted in LERO had more crystals, closer to each other and overlapped. This can explain that HSO has a higher hardness than HPO or HLERO, for a same SFC value, when diluted in LERO. Polymorphism was also observed by powder X-ray diffraction. The variability in hardness for samples having the same SFC is due to various crystal types and/or network structures that are formed upon crystallization of hard fats. This work demonstrates that for binary blends of studied oils, changes in the hardness are controlled mostly by the SFC, polymorphism and also by the material’s microstructure.     

Oxidatively Derived Volatile Compounds in Microencapsulated Fish Oil Monitored by Solid-phase Microextraction (SPME)

The stability of microencapsulated fish oil was studied during storage at 4 °C for up to 20 wk. Different coating mixtures consisting of gelatin or caseinate in blends with carbohydrates (sucrose, lactose, maltodextrin) were investigated. Oxidative stability of the microencapsulated fish oil was monitored by analysis of volatile compounds using gas chromatography olfactometry (GC‐O) or GC flame ionization (GC‐FID) (SPME‐HS‐GC/O or GC/ FID and HS‐GC/MS), Oxipres test, thiobarbituric acid‐reactive substances (TBARS), and sensory analysis. Coating mixture of caseinate and lactose showed slightly better stability than the sucrose and maltodextrin caseinate mixtures. Combination of fish gelatin and maltodextrin did not show as good oxidative stability as the coating blend of caseinate, lactose, and lecithin. Hexanal, 2‐nonenal and 2,4‐decadienals were selected as quality indicators to monitor the lipid oxidation during storage of the samples. SPME‐GC‐O analysis of these indicators showed that they were representative for the oxidation occurring in the microencapsulated fish oil. SPME‐GC‐FID analysis was sensitive enough to detect oxidative changes during storage. Oxidative stability test, TBARS results, and sensory analysis were in agreement with the SPME, indicating that SPME (polydimethylsiloxane/divinylbenzene [PDMS/ DVB] fiber) can be a useful tool for rapid analysis of lipid oxidation in microencapsulated fish oil.     

Evaluation of a reversed phase high performance liquid chromatographic column for estimation of legume seed oligosaccharides

The retention characteristics of the major legume seed oligosaccharides (sucrose, raffinose, stachyose and verbascose), and also those of some minor oligosaccharide components of soybeans, lupin seeds and fermented soybean products, were investigated using an RP-18 reversed phase column. Excellent separation of sucrose, raffinose and stachyose from one another and from minor oligosaccharide components was achieved using distilled water as the mobile phase, but verbascose could not be determined separately as it coeluted with raffinose. Addition of salts to the mobile phase increased retention and improved selectivity of separation. Rapid and reasonably efficient separation of sucrose, raffinose, stachyose and verbascose was achieved when 0.3 m ammonium sulphate was used as the mobile phase. These oligosaccharides were clearly resolved from minor oligosaccharide components. A comparison of the retention characteristics of the reversed phase column with those of a continuously modified plain silica column, using an acetonitrile/water/ amine modifier mixture as mobile phase, revealed major differences in selectivity which may be of value for separation and identification purposes.     

响应曲面法优化合成大豆油蔗糖多酯工艺

以大豆油脂肪酸乙酯和蔗糖为原料,十六烷基三甲基溴化铵作相转移催化剂,采用两步法合成大豆油蔗糖多酯。采用响应曲面分析法中的Box-Behnken 模型对影响大豆油蔗糖多酯产率的4 个主要因素(反应温度、催化剂用量、酯糖物质的量比、反应时间)进行优化。优化出的最佳合成条件为反应温度135.6℃、催化剂用量4.1%、酯糖物质的量比13.5:1、反应时间5.5h。在此条件下,蔗糖多酯的产率达90.72%,酯化度达7.1。     

Time- and temperature-dependent changes in the adsorbed layer on caseinate-stabilized emulsion droplets

Changes in composition of the adsorbed layer in sodium caseinate emulsions stored at different temperatures have been observed. These changes are, in part, dependent on the oil droplet phase (milk-fat or soybean oil). At storage temperatures below 15°C the milk-fat emulsion adsorbed layer exhibits a decrease in surface coverage as a result of casein molecule desorption. This was not observed for soybean oil emulsions. Above 15°C storage temperatures there is a time-dependent and temperature-dependent polymerization of casein molecules in both milk-fat and soybean oil emulsion droplet adsorbed layers. At temperatures below 15°C these changes are explained in terms of the different solid-fat contents of milk-fat and soybean oil. Above 15°C it is hypothesized that chemical changes in the adsorbed layer are taking place.     

豆乳加工中晚期糖基化终产物的调控

目的:通过模拟豆乳的加工条件,考察影响豆乳加工中晚期糖基化终产物(advanced glycation end products,AGEs)形成的因素。方法:采用荧光光谱法(λ_(ex)/λ_(em)=340 nm/465 nm)检测豆乳中荧光性AGEs含量,考察各因素:加工条件(煮沸时间、糖种类、糖添加量和脂肪含量)、贮藏条件(温度和时间)和食源性黄酮(槲皮素、芦丁、染料木素、木犀草素和儿茶素)对荧光性AGEs形成的影响;结果:豆乳体系中,糖种类对荧光性AGEs的影响从低到高依次为:木糖醇蔗糖果葡糖浆葡萄糖果糖;煮沸时间、糖添加量和脂肪含量均与荧光性AGEs形成呈正相关;在贮藏过程中,荧光性AGEs随着贮藏温度的提高、贮藏时间的延长而增多;黄酮能够有效抑制豆乳加工和贮藏过程中荧光性AGEs的形成,芦丁在2 mmol/L时,抑制效果最好。结论:通过部分条件的改变,如煮沸保持时间、糖种类、糖添加量、脂肪含量、贮藏条件和加入适量的AGEs抑制剂,在一定程度上调控AGEs的形成是可行的。     

低聚物对生物基聚对苯二甲酸丙二醇酯结晶性能的影响

逐步缩聚聚合物中通常含有一定比例的线性及环状低聚物,会影响纤维材料的成形加工、纤维性能、纺织品加工等。为探究低聚物对生物基对苯二甲酸丙二醇酯(PTT)结晶性能的影响,通过外部添加法制备得到具有不同低聚物质量分数(主要以环状二聚体为主)的生物基 PTT ,采用差示扫描量热仪分析方法对生物基PTT的结晶动力学进行研究。结果表明:低聚物的存在主要起成核剂的作用,其质量分数的增加可提高生物基 PTT的结晶速率、结晶温度及结晶度;添加低聚物质量分数为10%时,生物基 PTT的结晶速率常数由未添加的0.528提升至0.603,同时结晶温度由172.11 ℃提升至178.85 ℃。     

大豆种子萌发后油脂体乳液稳定性的研究

以大豆为原料,大豆种子经萌发处理后的油脂体乳液为研究对象,通过测量乳化稳定性、过氧化值、硫代巴比妥酸值（TBARS值）及酸价等指标,比较了大豆种子不同萌发时间油脂体乳液的稳定性,研究了不同处理条件（NaCl浓度、pH、贮藏温度）对大豆种子萌发后油脂体乳液稳定性的影响。实验结果表明,大豆种子萌发后油脂体提取率逐渐降低,20 h（12.36%±0.21%）至27 h（10.89%±0.28%）油脂体提取率呈逐渐下降趋势,且27 h后提取率下降显著（P<0.05）。室温下贮藏14 d样品出现不同程度的絮凝。不同萌发时间油脂体乳液稳定性也不同,27 h表面疏水性（99.78±0.88）最大,且乳化稳定性（23.49±0.39）最好。经不同NaCl浓度、pH、贮藏温度处理后,随NaCl浓度的增加,萌发后的大豆油脂体乳液乳化活性无显著变化（P>0.05）,乳化稳定性在NaCl浓度为0~150 mmol/L时呈下降趋势,大于150 mmol/L时无显著变化,150与200 mmol/L时分别为（4.75±0.12）和（4.74±0.14）min,但过氧化值在贮藏0~6 d时显著增加（P<0.05）;pH越高,萌发大豆油脂体乳液的ζ-电势及乳化活性越小,pH为4时乳化活性为（19.13±0.23）m2/g,过氧化值和TBARS值变化显著（P<0.05）;贮藏温度上升,萌发大豆油脂体乳液过氧化值升高,酸价无显著性变化（P>0.05）。不同萌发时间大豆种子油脂体乳液稳定性均存在差异,且萌发27 h后的大豆油脂体较其他萌发时间更稳定。NaCl浓度和pH都对萌发大豆油脂体乳液稳定性有较大影响,且贮藏温度对其影响相对较小。可为今后萌发大豆油脂体的应用提供理论基础。     

Droplet characterization and stability of soybean oil/palm kernel olein O/W emulsions with the presence of selected polysaccharides

Droplet characteristics, flow properties and stability of egg yolk-stabilized oil-in-water (O/W) emulsions as affected by the presence of xanthan gum (XG), carboxymethyl cellulose (CMC), guar gum (GG), locust bean gum (LBG) and gum Arabic (AG) were studied. The dispersed phase (40%) of the emulsions was based on soybean oil/palm kernel olein blend (70:30) that partially crystallized during extended storage at 5 °C. In freshly prepared emulsions, the presence of XG, CMC, GG and LBG had significantly decreased the droplet mean diameters. XG, LBG, GG and CMC emulsions exhibited a shear-thinning behavior but AG emulsion exhibited a Bingham plastic behavior and control (without gum) emulsion almost exhibited a Newtonian behavior. Both control and AG emulsions exhibited a severe phase separation after storage (30 days, 5 °C). The microstructure of stored XG emulsion showed the presence of partially coalesced droplets, explaining a large increase in its droplet mean diameters. Increases in droplet mean diameters and decreases in flow properties found for stored GG and LBG emulsions were attributed to droplet coalescence. Nevertheless, the occurrence of droplet coalescence in these emulsions was considered to be small as no free oil could be separated under centrifugation force. Increases in flow properties and excellent stability towards phase separation found for stored CMC emulsion suggested that CMC could retard partial coalescence. Thus, the results support the ability of CMC, GG and LBG in reducing partial coalescence either by providing a sufficiently thick continuous phase or by acting as a protective coating for oil droplets.     

High-intensity ultrasound assisted-emulsification using ionic liquids as novel naturally-derived emulsifiers for food industry applications

Over the last decade, conscious food consumption has been revolutionizing the food industry. The search for additives that meet concepts of naturalness, healthiness and sustainability represents one of the major challenges in food industry. The development of emulsifiers in the ionic liquid (IL) form using compounds that can be obtained from natural sources to replace conventional ones is a promising approach. In this work, we have reported the application of bio-based ILs derived from fatty acids (FAs) and choline (Ch) as novel emulsifiers to produce potential food-grade oil-in-water emulsions by pre-mixing (PM) or PM followed by high-intensity ultrasound (HIUS)-assisted process (PM + U). The effects of the type of IL, considering molecular structures of FAs (C₁₈OOH or C_18:1OOH) and vegetable oil concentration (30:70 or 70:30, oil:water ratio) to form and stabilize emulsions were evaluated. The study was focused on the following aspects: synthesis and characterization of ILs, and kinetic stability, droplet size and size distribution, optical microscopy, viscosity profile and rheological behavior of the emulsions. ILs presented high emulsifier ability, since some emulsions were stable after storage time of at least 30 days, being such stability related to the type of IL, oil concentration and emulsifying process. The observed behavior was associated to lower droplet size and/or emulsion viscosity. [Ch][C₁₈OO] presented higher emulsifier ability than [Ch][C_18:1OO], and this behavior was more evident at higher oil concentration. Emulsions obtained by PM presented phase separation after their preparation, whereas most of those prepared by PM + U were visually stable, being those containing higher oil concentration the formulations that presented higher viscoelasticity, with a gel like behavior. Therefore, bio-based ILs have promising application potential as emulsifiers, and their use to obtain high stable emulsions can be enhanced by using the HIUS technique.     

大豆-坚果奶酪类似物的制备及其性质研究

该研究采用大豆乳、腰果乳及巴旦木蛋白为原料制备一种奶酪类似物,目的是确定最佳工艺配方以制备出高品质的大豆-坚果奶酪类似物,然后评价其理化性质、感官特性、储藏稳定性和消化特性。研究结果显示：具有最佳品质的大豆-坚果奶酪类似物基本配方为（皆为质量分数）：腰果乳50.00%,大豆乳50.00%;并以植物乳质量为基准,依次添加植物油3.09%（椰子油与葵花籽油比例为7:3）、巴旦木蛋白2.01%、TG酶0.33%、柠檬酸0.10%、乳酸0.10%;以凝乳质量为基准,添加胶体1.08%、蔗糖4.00%。大豆-坚果奶酪类似物硬度值0.88 N、整体感官评分7.71分,可以与商品化动物奶酪相媲美。此外,随着储藏时间增加其硬度值从0.94 N增加到1.15 N,无明显变硬和析水现象。体外消化结果显示其蛋白电泳条带在肠道消化180 min后全部消失,游离脂肪酸释放速率为60%。因此,制备的大豆- 坚果奶酪类似物营养价值高,具有较佳的感官品质,储藏稳定性好且蛋白易于消化,能够作为动物奶酪的替代物以满足人们对奶酪的需求。     

Improvement of Freeze-Dried Lactobacillus Plantarum Survival Using Water Extracts and Crude Fibers from Food Crops

A synbiotic product of combined Lactobacillus plantarum TISTR 875 with water extracts and crude fibers from corn, mungbean, and soybean was formulated to investigate the survival of L. plantarum during freeze-drying and storage. The impacts of those water extracts and crude fibers on probiotic survival were determined in both a cultural medium and a freeze-drying medium. L. plantarum cultivated in de Man, Rogosa, and Sharpe (MRS) broth containing 2 % of water extract from soybean with 2 % mungbean fiber showed only 0.11 log CFU/ml cell reduction. The survival of L. plantarum harvested at the late log phase, mid stationary, phase and late stationary phase did not show statistical significance (P?>?0.05), whereas an initial pH of 6.5 and growth temperature of 37 °C showed greater impact (P?<?0.05). The addition of corn extract to the freeze-drying medium as a cryoprotectant had a similar effect on L. plantarum survival as sucrose, but it was better (P?<?0.05) than fructo-oligosaccharide and exopolysaccharides from Weissella cibaria A2, soybean extract, mungbean extract, soybean, corn, and mungbean fibers. A protective coating of corn extract was revealed and observed using scanning electron microscopy. The freeze-dried L. plantarum, cultivated in MRS broth containing soybean extract and mungbean fiber with corn extract as a cryoprotectant, retained high viability of 7.21 and 6.88 log CFU/ml after 8-week storage in a vacuum-packed aluminum foil-laminated polyethylene sachet and a nitrogen-flushed glass vial, respectively.     

番茄红素的提取及其在大豆油中稳定性、抗氧化性的研究

用有机溶剂从番茄原料中提取番茄红素油树脂,采用皂化法与重结晶相结合的方法来纯化番茄红素油树脂得到番茄红素晶体。考察了时间、温度、光照对溶于大豆油中的番茄红素稳定性的影响;并对不同添加量番茄红素对大豆油的抗氧化性进行了实验。结果表明,番茄红素在大豆油中的保存率随着贮存时间的延长而降低,低温避光贮存比高温光照贮存的保存率高。高添加量番茄红素对大豆油的抗氧化效果显著。     

FULLY HYDROGENATED VEGETABLE OIL AS A STABILIZER FOR LOW FAT BUTTER SPREADS

A blend containing hydrogenated fat and a liquid oil was used for preparation of low fat butter spreads. The effects of maltodextrin (MD), skim milk powder (SKMP), guar gum and fully hydrogenated (hardened) vegetable oil on spreadability and phase separation of low fat butter spreads with 30% water were studied. Oil separation in bulk storage and on centrifugation in spreads containing MD, SKMP and guar gum was observed. However, the products prepared by incorporation of 2% hardened oil did not show any oil separation at 25 or 36C. The fat content of the spreads was reduced to 57% by incorporating MD or SKMP along with hardened oil. The spreads showed better spreadability at refrigerated temperatures and better stand up properties at high storage temperatures compared to commercial butter.     

大豆油在储存过程中的变化

收集储备大豆原油在储存过程中酸值和过氧化值的数据,分析其在储存过程中的变化规律。结果表明:大豆原油的酸值和过氧化值变化规律相同,酸值随着储存时间的延长呈缓慢线性增长,年变化值在0.2～0.4 mg/g,过氧化值随着储存时间延长呈平稳慢慢上升趋势,其变化值受环境温度影响较大,在外部温度和氧气突然增加时过氧化值迅速上升,当达到一定值后分解下降。