Moisture sorption and thermodynamic properties of cassava starch and soy protein concentrate based edible films

Moisture sorption isotherms and thermodynamic properties of cassava starch and soy protein concentrate–based edible films were investigated. Equilibrium moisture content was determined at various temperatures (10, 20, 30 and 40 °C) and relative humidities (17–83%) using gravimetric method, and the results were analysed using four sorption isotherm models. The equilibrium moisture of edible films (both adsorption and desorption modes) decreased with soy protein concentrate addition and temperature at constant water activity. The monolayer moisture content values of cassava starch–soy protein concentrate edible films decreased with increase in temperature and soy protein level. GAB and Oswin models (%RMS ≤10) best described the isotherms of the biofilms with the monolayer moisture contents, isosteric enthalpy and entropy higher for adsorption with significant kinetic compensations. The moisture sorption and thermodynamic properties of cassava starch–soy protein concentrate edible films showed that they are suitable for packaging applications.     

Effect of the amount of concentrate offered in an automated milking system on dry matter intake,milk yield,milk composition,ruminal digestion,and behavior of primiparous Holstein cows fed isocaloric diets

The objective of this study was to determine if the quantity of concentrate provided in an automated milking system (AMS) affects dry matter intake (DMI), attendance to the AMS, milk and milk component yield, feeding behavior, cow activity, and ruminal fermentation of lactating dairy cows fed isocaloric diets. Eight ruminally cannulated primiparous Holstein cows were used in a replicated 4 × 4 Latin square design with 28-d periods. Cows were housed in a freestall facility with a guided-traffic (feed-first) flow barn design. Treatments included 0.5, 2.0, 3.5, or 5.0 kg/d of dry matter of pellet in the AMS with an equivalent reduction of the same pellet in the partial mixed ration (PMR). Days 21 to 24 of each treatment period were used for DMI, milking performance (visits, yield, and composition), behavior, and ruminal pH determination, and d 25 to 28 were used for ruminal short-chain fatty acid and ammonia concentrations as well as total-tract digestibility. As imposed, consumption of AMS pellet linearly increased, equating to 0.50, 2.00, 3.49, and 4.93 kg of dry matter/d for the 0.5, 2.0, 3.5, and 5.0 kg/d treatments, respectively. Correspondingly, the standard deviation in AMS pellet intake among days linearly increased from 0.06 to 0.85 kg of dry matter/d as the quantity of concentrate in the AMS increased from 0.5 to 5.0 kg. The PMR DMI decreased linearly with increasing AMS concentrate allocation, but total DMI (PMR + AMS) was not affected (25.3 kg/d). As the AMS concentrate allocation increased, the selection against particles retained on an 18-mm sieve linearly increased and selection against particles retained on the pan decreased. Milking frequency (3.22 milkings/d), milk yield (37.5 kg/d), milk fat yield (1.43 kg/d), and milk protein yield (1.22 kg/d) were not affected; however, milk urea nitrogen concentration decreased linearly with increasing AMS concentrate. Ruminal pH averaged 6.18 and was not affected by AMS concentrate. Total ruminal short-chain fatty acid concentration was greatest when 3.5 kg of concentrate was allocated in the AMS and ruminal ammonia decreased linearly with increasing AMS concentrate. Time spent lying, the number of lying bouts, and average bout duration were not affected by treatment. These data indicate that increasing the quantity of concentrate in the AMS increases daily variability in AMS concentrate intake while decreasing PMR intake without affecting voluntary visits to the AMS and milk or milk component yield. As such, under isocaloric dietary settings, increasing the supply of pellet in the AMS is not likely to affect voluntary visits to the AMS, milk and milk component yields, or ruminal fermentation.     

利用生产大豆浓缩蛋白副产物发酵酒精的研究

该文利用大豆糖蜜发酵制备酒精,研究了发酵时间、发酵温度、糖蜜浓度、接种量、pH对发酵酒精的影响,并通过正交试验对糖蜜发酵生产酒精工艺条件进行优化,确定其最佳发酵条件为:糖蜜浓度55g/L,发酵温度32℃,发酵时间72h,接种量9％,pH5.0.在最佳条件下,大豆糖蜜发酵酒精得到的酒精度为7.3％vol.     

大豆浓缩蛋白改性及应用前景分析

本文综述大豆浓缩蛋白(soy protein concentrate,SPC)的研究现状,展望SPC改性后的应用前景。SPC的生产方法主要有传统的稀酸洗涤法、环保型醇提法和新工艺超滤膜法3种。SPC改性方法主要有热、微波、超声波、生物酶等8种方法来提高其功能特性和生物特性。改性后的功能性SPC可作为食品工业和饲料工业中最重要的营养物质,其应用前景十分广泛。     

馥郁香型白酒等级鉴别的研究

目的建立超高效液相色谱-四极杆/静电场轨道阱高分辨质谱法和主成分分析法对馥郁香型白酒等级鉴别的方法。方法白酒样品过0.22μm滤膜后上机测试,利用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱法检测。高分辨质谱采用Full MS-dd MS2模式对酒样中物质进行定性检测。基于mz Cloud谱图库建立含有158种风味物质的数据库,直接鉴定酒样物质,并采用主成分分析法(principal component analysis,PCA)对其进行分析。结果本实验通过数据库比对可直接鉴定出52°馥郁香型白酒中73个白酒中的微量成分,且馥郁香型白酒原样A1级和A2、A3级可以实现很好的区分。结论该方法简单、快速,为馥郁香型白酒质量分级提供了一种新的途径。     

Phenolic content and antioxidant capacity of supercritical carbon dioxide-treated and air-classified oat bran concentrate microwave-irradiated in water or ethanol at varying temperatures

Oat bran concentrate (OBC) was defatted with supercritical carbon dioxide (SCD), then microwave-irradiated (MI) at 50, 100 or 150 °C for 10 min in water, 50% or 100% ethanol, and extract pH, soluble solids, phenolic content (PC) and antioxidant capacity (AC) were analysed. OBC was air-classified into five fractions and MI in water at 150 °C. OBC without SCD and microwave irradiation was extracted at 22 °C. Most effective temperature during microwave irradiation for maximising extraction of PC and AC was 150 °C. Defatted OBC in 50% ethanol and MI at 150 °C extracted greatest PC and AC. SCD treatment slightly reduced PC and AC. OBC extracted in water or 50% ethanol at 22 °C without microwave irradiation had similar PC and AC than OBC MI at 150 °C, but much higher levels were observed for latter heat treatment using absolute ethanol. Air-classification shows potential to enhance PC and AC.     

Short communication: Muscle protein synthetic response to microparticulated whey protein in middle-aged men

Whey protein concentrate (WPC) is a high-quality dairy ingredient that is often included in formulated food products designed to stimulate muscle anabolism. Whey protein concentrate can be affected by UHT processing, and its sensory properties are not compatible with some formulated food products. Microparticulated WPC (mWPC) is a novel ingredient that is resistant to heat treatment and has enhanced sensory properties. When 16 healthy middle-aged men consumed 20 g of either WPC or mWPC, both proteins increased plasma essential AA and leucine concentrations with no detectable difference in curve kinetics. Myofibrillar protein synthesis was increased in both groups for 90 min after ingestion with no difference between groups. Ingestion of mWPC resulted in a muscle anabolic response that was equivalent to that of WPC over the full 210-min measurement period. Formulated products incorporating mWPC or standard WPC would provoke equivalent anabolic responses.     

浓缩酪蛋白胶束成分的影响因素及其在奶酪生产中的应用

目前,采用膜过滤技术可从脱脂奶中分离酪蛋白,随后通过浓缩、杀菌、干燥等工艺获得浓缩酪蛋白胶束。对浓缩酪蛋白胶束成分的影响因素及其在奶酪生产中的应用进行综述,发现膜过滤期间的pH值、温度和洗滤条件均会影响浓缩酪蛋白胶束的成分,使其具有不同浓度的酪蛋白、乳清蛋白、乳糖以及钙。而且可以利用浓缩酪蛋白胶束标准化原奶,从而制备成分和品质一致的奶酪;也可以利用不同成分的浓缩酪蛋白胶束获得不同的原奶组合物,从而制备所需品质和功能的奶酪。总之,在奶酪生产过程中添加浓缩酪蛋白胶束能够影响奶酪的成分、质地以及风味等,但通过调整膜过滤和奶酪生产的工艺参数可以解决这些问题。未来还需获得一种经济有效的方式来保存浓缩酪蛋白胶束,赋予其更长的保质期,良好的凝乳酶凝乳特性,从而保证奶酪的品质和产量。     

基于PCR-CE技术的NFC橙汁与FC橙汁鉴别

摘 要：以特洛维塔、早金、哈姆林3 种甜橙为原料,按照市售橙汁的主要生产工艺,模拟制备非复原（not from concentrated,NFC）橙汁和复原（from concentrated,FC）橙汁。针对甜橙叶绿体成熟酶K蛋白基因（maturase K,matK）和烟酰胺腺嘌呤二核苷酸脱氢酶基因（nicotinamide adenine dinucleotide dehydrogenase,ndhF）,共设计8 对引物用以扩增得到不同长度的目标条带,结合聚合酶链式反应（polymerase chain reaction,PCR）和毛细管电泳（capillary electrophoresis,CE）技术分析了鲜榨、均质、巴氏杀菌、浓缩、二次巴氏杀菌关键加工工艺,对特洛维塔橙汁叶绿体matK和ndhF基因的DNA降解变化的影响,探讨NFC橙汁与FC橙汁DNA降解程度的差异,筛选出NFC橙汁和FC橙汁的特征差异性片段组,建立基于PCR-CE技术的NFC橙汁与FC橙汁鉴别方法。该方法适用于分析货架期内的NFC橙汁与FC橙汁,且同样适用于早金和哈姆林甜橙为原料的NFC橙汁与FC橙汁的鉴别。应用该方法对市售NFC橙汁进行检测,发现市售NFC橙汁存在标签不符的现象。本研究建立的基于PCR-CE技术的NFC橙汁与FC橙汁定性鉴别方法可以为果汁行业的有效监管提供技术支撑。