Water Vapor Adsorption Isotherms of Guava, Mango and Pineapple

Isotherms were determined at 25° and 50°C, using an electronic water activity meter. For the 3 fruits temperature had practically no effect on the isotherms. Sorption capacity of freeze-dried pineapple was higher than that for vacuum dried. The higher sorption capacity of mango and pineapple in comparison to guava corresponded to the respective sugar contents of the fruits.     

热改性蛋清粉的贮藏稳定性

为了解热改性蛋清粉的贮藏稳定性,文中对室温贮藏(12个月)的热改性蛋清蛋白功能性和分子特点进行了分析。研究表明:在贮藏期热改性蛋清粉的凝胶性、乳化性、泡沫性都有不同程度的降低,同时疏水性、巯基含量和分子柔性也有明显变化。相关性分析表明:热改性蛋清粉功能性的下降与分子结构的变化显著(P<0.05)相关。蛋白质分子特点是影响热改性蛋清粉的贮藏稳定性主要因素。     

Physicochemical Responses and Quality Changes of Turbot (Psetta maxima) During Refrigerated Storage

The sensory, physicochemical, microbiological, and volatiles changes of postmortem turbot during 20 days of chilled storage at 4°C were studied. No significant changes were found in pH value and whiteness during the storage, while total viable counts, total volatile base nitrogen, and K-values increased significantly with storage time. The textures profile, springiness and resilience, and sensory attributes changed significantly during storage. A total of 50 volatile compounds including aldehydes, ketones, esters, alcohols, alkenes, alkanes, aromatics, amines, and others were identified in turbot muscle during storage by the solid-phase microextraction and gas chromatography–mass spectrometry methods. Among these volatile components, the relative content of some decreased significantly with time, while others increased significantly. The results suggested that hardness, springiness, resilience, sensory attributes, total volatile base nitrogen, K-value, and total viable counts combined with some volatile compounds could more perfectly reflect the quality changes of turbot during storage. The study indicated that turbot fillets stored at 4°C maintain better quality for 16 days during storage.     

超滤法浓缩分离免疫初乳中的抗体

收集经大肠杆菌、沙门氏菌混合疫苗免疫处理的乳牛产后７天之内初乳,经去脂、去酪蛋白后所得免疫初乳乳清,用中空纤维超滤器（分子截留为１００ｋｕ（１００ｋｄ）进行浓缩分离,浓缩４．５～７倍、ＩｇＧ收率在９０％以上。为了制得高纯度ＩｇＧ分离物,可和３５％饱和度的硫胺进行盐析,然后再进行超滤脱盐、浓缩、制得的ＩｇＧ浓缩物纯度达８０％以上,这一工艺适合工业化生产。     

喷雾干燥与冷冻干燥鸡蛋粉特性研究

以鲜鸡蛋为原料,利用喷雾干燥和冷冻干燥技术制备鸡蛋粉,对比2种蛋粉水分含量、水分活度、溶解度、色差、微观结构等理化性质,同时检测起泡性、乳化性,并选用喷雾干燥蛋黄粉制备凝胶探讨功能特性。结果表明:喷雾干燥蛋粉和冷冻干燥的蛋粉水分含量、水分活度、溶解度和色差差异显著(P<0.05),且喷雾干燥蛋粉和冷冻干燥蛋粉起泡性及乳化性均在氯化钠浓度为0.5 g/100 mL时达到最大值;制备凝胶最佳条件为加水量为150%、氯化钠浓度为3%、温度100℃、热处理15 min。此项研究将对蛋粉的应用奠定理论基础。     

玉米黄色素稳定性的研究

以玉米为原料,对影响玉米黄色素稳定性的因素进行研究.结果表明:玉米黄色素的最大吸收波长为448 nm,该色素不耐高温,日光照稳定性差;pH对玉米黄色素的稳定性无影响;除金属离子Fe3+、Al3+外,大多数金属离子对玉米黄色素无影响;低浓度糖、高浓度抗坏血酸对玉米黄色素有一定保护作用;而双氧水、苯甲酸钠、山梨酸钾对色素有明显的破坏作用.     

Survival of Microencapsulated Probiotic Bacteria after Processing and during Storage: A Review

The use of live probiotic bacteria as food supplement has become popular. Capability of probiotic bacteria to be kept at room temperature becomes necessary for customer's convenience and manufacturer's cost reduction. Hence, production of dried form of probiotic bacteria is important. Two common drying methods commonly used for microencapsulation are freeze drying and spray drying. In spite of their benefits, both methods have adverse effects on cell membrane integrity and protein structures resulting in decrease in bacterial viability. Microencapsulation of probiotic bacteria has been a promising technology to ensure bacterial stability during the drying process and to preserve their viability during storage without significantly losing their functional properties such acid tolerance, bile tolerance, surface hydrophobicity, and enzyme activities. Storage at room temperatures instead of freezing or low temperature storage is preferable for minimizing costs of handling, transportation, and storage. Concepts of water activity and glass transition become important in terms of determination of bacterial survival during the storage. The effectiveness of microencapsulation is also affected by microcapsule materials. Carbohydrate- and protein-based microencapsulants and their combination are discussed in terms of their protecting effect on probiotic bacteria during dehydration, during exposure to harsh gastrointestinal transit and small intestine transit and during storage.     

速溶即食板栗粉的防褐变和稳定性研究

针对板栗原料的特性和板栗深加工产品的现状 ,对速溶即食板栗粉加工过程中的防褐变和稳定性问题进行了详细实验分析研究 ,提出了抑制其褐变、提高其稳定性的有效方法     

Storage Stability of Protein Hydrolysate from Yellow Stripe Trevally (Selaroides leptolepis)

Storage stability of protein hydrolysate from yellow stripe trevally prepared using Flavourzyme with a degree of hydrolysis of 25% (HF₂₅) was determined. During storage, slight increases in water activity and moisture content and a slight decrease in lightness of HF₂₅ and Bacto Peptone were observed. Generally, browning intensity, A₂₉₄, and fluorescent intensity of HF₂₅ and Bacto Peptone increased. Both samples had an excellent solubility at pH 5 and 7. Thiobarbituric acid reactive substances in HF₂₅ and Bacto Peptone increased (p < 0.05). The efficacy of HF₂₅ as media for bacteria was equivalent to that of Bacto Peptone and was quite stable during storage.     

Effect of Encapsulating Materials on Water Sorption,Glass Transition and Stability of Juice From Immature Acerola

Immature acerola juice was dehydrated by spray drying, using as encapsulating material maltodextrin DE25, arabic gum, or a mixture of both in different proportions. A constant ratio of 1:1 was kept between juice solids and encapsulating material. The effect of encapsulation materials on water sorption, glass transition, and physical properties of encapsulated immature acerola juice was investigated. The monolayer moisture of the encapsulated juices, calculated according to the GAB theory, varied from 5.11 to 5.73g H₂O/100g of solids (25°C). The glass transition temperature (T_g) of maltodextrin and gum arabic varied from 60 (a_w 0.33) to 38°C (a_w 0.54), and from 62 (a_w 0.33) to 42.6°C (a_w 0.54), respectively. The addition of juice to the encapsulating materials decreased the T_g of the juice powder to 39.5–41.3°C (a_w 0.33) and 1.84–8.05°C (a_w 0.54), but no marked differences were found among the juice powders. The critical a_w, i.e., the point of onset of physical alterations in the encapsulated materials, was higher than the corresponding monolayer values. Stickiness was observed at temperatures close to T_g, and collapse occurred at temperatures of 20°C or more above the T_g. Maltodextrin DE25 and gum arabic offered equivalent contributions to the stability of the system.     

Stability of bixin in annatto oleoresin and dye powder during storage

Annatto dye is a natural colour extracted from the pericarp of seed of Bixa orellana L. Bixin is the principle colouring agent, and can be extracted from the annatto seeds into oil, alkali and organic solvents. Considerable losses were reported during storage in bixin content of annatto dye depending upon the conditions. In the present study, the loss of bixin in annatto dye stored in the form of dye powder or annatto oleoresin at three different conditions, viz; cold conditions in darkness, in darkness at room temperature (RT) and at RT in diffused daylight were evaluated spectrophotometrically at 470 nm in choloroform. Accordingly, annatto oleoresin and dye powder of approximately equivalent bixin strengths were exposed to different storage conditions in glass bottles for a period of 360 days. The losses were very high in the case of dye powder when compared to the oleoresin under all the storage conditions. Mass fraction of bixin lost in oleoresin stored at cold dark conditions was negligible (0.011) throughout the study, whereas considerable losses were observed in dye powder (0.229). The mass fraction of bixin lost in oleoresin and dye powder samples stored at RT (dark) were 0.082 and 0.542 respectively. Similarly in case of RT (diffused day light) conditions, the losses of bixin in oleoresin and dye powder were 0.136 and 0.600, respectively. Loss of 0.154 was observed in bixin content in the seed stored in jute bags during the period. The second-order rate constants for degradation of bixin were calculated, and were found to be much lower for oleoresin when compared to dye powder. It is recommended that the dye can be conveniently stored in the oleoresin form until it is formulated for application in foods.     

Effects of nanorod-rich ZnO on rheological,sorption isotherm,and physicochemical properties of bovine gelatin films

The effects of nanorod-rich zinc oxide (ZnO–nr) on the flow properties of bovine gelatin solution and on the sorption isotherm, antimicrobial, and physchochemical properties of gelatin films were investigated. ZnO–nr was incorporated into gelatin solutions at different concentrations (0.01, 0.02, 0.03, and 0.05 g/g dried gelatin). The introduction of low ZnO–nr concentrations (0.05 g/g dried gelatin) to gelatin solutions significantly increased the viscosity of the solution from 9 to 11.9 mPa s and decreased the permeability of the films to water vapor from 8.9 × 10⁻¹¹ to 1.78 × 10⁻¹¹ (g m⁻¹ s⁻¹ Pa⁻¹). Solubility in water decreased from 30% to 20%, and monolayer water content of the films decreased from 0.13 to 0.10 (g water/g dried solid), whereas their contact angle increased from 45° to 85° with increasing ZnO–nr concentration from 0 to 0.05 g/g dried gelatin. The ZnO–nr gelatin films had very low UV transmittance and were able to absorb more than 50% of the near-infrared spectra. These films showed excellent antimicrobial activity against Staphylococcus aureus. These properties suggest that ZnO–nr can be potentially used as fillers in gelatin-based films for active packaging materials in the pharmaceutical and food packaging industries.     

Recent Trends and Applications of Encapsulating Materials for Probiotic Stability

The importance of probiotics and their live delivery in the gastrointestinal tract has gained much importance in the recent past. Many reports have indicated that there is poor viability of probiotic bacteria in dairy based products, both fermented and non-fermented, and also in the human gastro-intestinal system is questionable. In this case, microencapsulation is the most significant emerging and efficient technology that is being used for the preservation of probiotics against adverse environmental conditions. Apart from different techniques of microencapsulation, various types of encapsulating materials are also used for the process, namely, alginate, chitosan, carrageenan, gums (locust bean, gellan gum, xanthan gum, etc.), gelatin, whey protein, starch, and compression coating. Each one of the encapsulating materials has its own unique characteristics of capsule formation and provision of shape, appearance, and strength to microbeads. The type of encapsulating material also influences the viability of probiotics during storage, processing, and in the gastrointestinal tract. The effectiveness of any material depends not upon its capsule forming capability, strength, and enhancing viability but also on its cheapness, availability, and biocompatibility. So, added convenience and reduced packaging costs may also be used to offset the cost of encapsulating one or more ingredients. Encapsulated forms of ingredients provide a longer shelf life for the product.     

Storage Stability of Chicken as Affected by Map and Lactic Acid Treatment

The effects of MAP and/or pretreatment with lactic acid buffer were studied on the shelf-life of broiler carcasses, under conditions simulating market storage (4 and 7°C) in the State of Kuwait. Pretreatment with lactic acid buffer increased treated carcass shelf-life by 6–7 days when stored at 4°C and 5–6 days at 7°C. Likewise, pretreatment of MAP carcasses with the same buffer extended the shelf-life to >36 and 35 days, compared with 22 and 13 days for the untreated MAP carcasses. Pretreatment of poultry with lactic acid buffer, with or without MAP, provides a potential alternative for improving the storage quality of poultry.     

干燥方式对湿法加工奶茶固体饮料感官和稳定性的影响

为了考察干燥方式对湿法加工奶茶固体饮料感官和稳定性的影响,本实验以喷雾干燥和真空干燥两种方式干燥奶茶固体饮料。结果表明,经过真空干燥的奶茶粉冲泡浮油严重,口感和组织状态显著差于喷雾干燥奶茶粉。真空干燥奶茶粉表面油含量为13.44%,而喷雾干燥仅为0.78%,通过粒径分布和透光率测定,均显示真空干燥奶茶粉稳定性差,喷雾干燥稳定性较佳。在得率方面,喷雾干燥得率59%,真空干燥74%。综合各项结果,喷雾干燥更适合干燥湿法奶茶固体饮料。     

Stability of quercetin derivatives in vacuum impregnated apple slices after drying (microwave vacuum drying,air drying,freeze drying) and storage

Microwave vacuum drying (MVD) was investigated for apple slices enriched with quercetin derivatives by vacuum impregnation (VI). Additional freeze drying (FD) and air drying (AD) were conducted. Compared to native apples, the impregnated tissue resulted in higher moisture content, elevation of weight and significant browning, due to the incorporated VI solution. The total quercetin content and quercetin glycoside composition were not affected by MVD and FD. The vacuum conditions protect the polyphenols from oxygen dependent degradation and browning reactions. AD resulted in an average quercetin glycoside loss of 44% and undesirable changes, particularly discoloration. The degradation is caused by both non-enzymatic and enzymatic reactions. The pulsed microwave energy intake improved the drying result in structure and led to a faster drying process of 130 min. The bulk density of MVD apple chips (0.69 g/ml) ranged between 0.33 g/ml for FD and 0.75 g/ml for AD. The final moisture content was the lowest after FD (6.8 g/100 g), followed by 9.0 g/100 g after MVD and 12.7 g/100 g after AD. The shelf life was significantly influenced by storage temperature and time. After 12 month at 20 °C, the total quercetin content decreased by 21%.     

原位协同鞣提高废弃皮粉热稳定性

我国是皮革生产和消费大国,每年要产生大量的皮革废弃物,其资源化再利用现已成为国内外关注的热点。将原位协同鞣制材料及方法应用于废弃皮粉处理过程,提高废弃皮粉的热稳定性,以满足废弃皮粉作为橡塑填充材料的工艺加工要求。实验结果显示：pH=3．0时,原位物为Indusol ATO,协同物为B1ancotan BC,用量分别为皮粉重量的10％和20％,处理后的废弃皮粉的热变性温度可达236．0℃,具有较高的热稳定性。当原位协同鞣制体系中均为大分子物质时,其加料顺序对处理后样品的Td有较大的影响;而原位物、协同物中有至少一种为小分子物质时,加入顺序对处理后样品Td影响较小。     

温度及光照对婴幼儿配方乳粉中VA、VD稳定性的影响

为研究不同温度条件下婴幼儿配方乳粉中VA和VD的稳定性,分别考察其在25、40、60℃及80℃储藏条件下乳粉中的含量变化;通过采用透光和避光2种方式储存的乳粉进行光照试验,研究了光照对乳粉中VA和VD稳定性的影响.结果 表明,25℃储藏条件下,乳粉中VA和VD含量均无明显变化;40、60℃和80℃条件下,VA含量有不同...