无酵母生淀粉酒精发酵的研究

利用根霉—3(Rhizopus—3)麸曲进行无酵母生淀粉酒精发酵研究。以生玉米淀粉为原料,无酵母酒精发酵醪液酒度8.5％(v/v,20℃),淀粉利用率84.87％。研究了该工艺过程中的一些条件。发现发酵终产物乙醇对生淀粉糖化酶的活性有抑制作用。生淀粉的糖化是该过程的限速步骤。15gRhizopus—3鲜曲的酒化力与10ml酒母相当。发酵时添加一定量的α-淀粉酶、纤维素酶或果胶酶有协同作用,可提高淀粉利用率。同时探讨了无酵母生淀粉酒精发酵的机制,认为选育具有高活性生淀粉糖化酶和酒化酶等复合酶系的菌种是关键问题。     

牡丹籽蛋白的制备工艺优化及功能性质评价

以脱壳后经超临界CO2萃取脱脂的牡丹籽粕为原料,采用碱溶酸沉法提取其中的蛋白质,在单因素试验的基础上,利用响应面法进行优化,确定提取牡丹籽蛋白的最佳工艺条件,并对提取的牡丹籽蛋白与大豆分离蛋白的一些功能性质进行比较研究。结果表明,牡丹籽蛋白的最佳提取工艺条件为:料液比1∶25,浸提p H 9.25,提取温度53.32℃,提取时间68.74 min,且影响因素主次顺序为浸提p H料液比提取时间提取温度;最佳工艺条件下的蛋白质提取率为62.95%,提取的牡丹籽蛋白中蛋白质含量为68.06%;牡丹籽蛋白的乳化稳定性和泡沫稳定性优于大豆分离蛋白,而其吸水性、吸油性、持水性、乳化性和起泡性却不如大豆分离蛋白。     

芝麻粕蛋白酶法提取工艺优化及组分分析

为了综合利用芝麻粕资源,以芝麻粕为原料,利用硬脂酸、吐温80、十二烷基硫酸钠三种表面活性剂对其进行脱脂处理,再采用水剂法去除表面活性剂,最后利用中性蛋白酶、碱性蛋白酶和木瓜蛋白酶对芝麻粕蛋白进行水解,以芝麻粕蛋白溶出率为考察指标优选出最佳水解酶。在此基础上,通过单因素试验和正交试验对酶解工艺条件进行优化,并利用2,4-二硝基氟苯柱前衍生高效液相色谱法分析水解物成分。结果表明,吐温80脱脂效果最好,芝麻粕脱脂率达93.49%;碱性蛋白酶为最佳水解酶,其最佳酶解条件为料水比1∶10（g∶mL）、酶解温度50 ℃、加酶量0.04%、酶解时间3.0 h。在此最佳酶解条件下,芝麻粕蛋白溶出率为88.94%。水解物中含有20种氨基酸,其中8种人体必需氨基酸含量高于FAO/WHO的推荐值。     

陶瓷色料在炻瓷无光釉中的应用

本文研究了陶瓷色料在中温炻瓷无光釉中的发色情况,利用色度仪测量了各色料的色度值,并分析了影响色料在无光釉中发色的因素。     

Sensitive Monoclonal Antibody-based Sandwich ELISA for the Detection of Porcine Skeletal Muscle in Meat and Feed Products

A monoclonal antibody‐based sandwich enzyme‐linked immunosorbent assay (ELISA) was developed for the sensitive detection of porcine skeletal muscle in raw and heat‐processed meat and feed products. Heat treatment of meat samples up to 132 °C for 2 h did not affect the assay performance. The assay uses a pair of monoclonal antibodies (MAbs 8F10 and 5H9) specific to skeletal muscle troponin I (TnI). MAb 8F10, reacting to mammalian TnI, is the capture antibody and the biotin‐conjugated MAb 5H9, specific to porcine TnI, the detection antibody. The sandwich ELISA is able to detect 0.05% (w/w) of laboratory‐adulterated pork in chicken, 0.1% (w/w) pork in beef mixtures, 0.05% (w/w) pork meal in soy‐based feed, and 1% commercial meat and bone meal (MBM), containing an unknown amount of pork, in soy‐based feed. This new assay provides a rapid and reliable means to detect the contamination of meat and feed products with trace amounts of porcine muscle tissue to ensure product quality and safety.     

Quantification of trace elements in raw cow’s milk by inductively coupled plasma mass spectrometry (ICP-MS)

The levels of trace elements are an important component of safety and quality of milk. While certain elements such as chromium are essential at low levels, an excess can result in deleterious effects on human health. International quality control standards for milk are published by the Codex Alimentarious Commission and levels of heavy metals in milk intended for human consumption are routinely monitored. This paper describes a new method for demonstrating the levels of V, Cr, Mn, Sr, Cd and Pb in raw cow’s milk, using an ICP-MS. Samples (n = 24) of raw cow’s milk were collected from dairy farms close to mines in Gauteng and North West Provinces of South Africa. In order to destroy organic matrix, each freeze dried milk sample was mineralised by using a microwave assisted digestion procedure. Concentrations of trace elements in digested milk samples were measured by ICP-MS. A whole milk powder reference material (NIST SRM 8435) was used to evaluate the accuracy of the proposed method. It was found that the levels of V, Cr, Mn, Sr, Cd and Pb obtained using the new method showed concordance with certified values.     

酶法制备花生粕醒酒多肽

为更合理有效地利用花生粕资源,制备具有醒酒作用的花生粕多肽,本实验以Alcalase AF 2.4L蛋白酶酶法制备花生粕醒酒肽,经分级分离后,通过体外和动物实验验证其醒酒效果。结果表明,花生粕醒酒肽制备最佳工艺条件为：酶解时间3 h、酶解温度35 ℃、pH 9.5及料液比1∶30（m/V）。该条件下乙醇脱氢酶（alcoholdehydrogenase,ADH）激活率及多肽得率均较高。经分级分离后,分子质量在1 000～3 000 D的多肽对ADH激活作用最强,激活率为30.47%。G25凝胶色谱分析表明,花生粕多肽中小于3 000 D的多肽占89.55%,ADH激活率为29.25%。动物实验证明,花生粕多肽对小鼠有显著的防醉醒酒作用。小鼠血液乙醇含量测定结果表明,高剂量的花生粕多肽在60～90 min内能显著降低小鼠血液中的乙醇含量。     

Physical and processing properties of milk,butter, and cheddar cheese from cows fed supplemental fish meal

Physical, chemical, sensory and processing properties of milk produced by feeding a rumen-undegradable fish meal protein supplement to Holstein cows were investigated. The supplement contained (as fed basis) 25% soft-white wheat, 60% herring meal, and 15% feather meal. The total fat level in the milk decreased to 2.43%. For both pasteurized and ultra-high temperature processed drinking milk, no difference was found between fish meal (FM) milk and control milk in terms of color, flavor and flavor stability; in particular, no oxidized flavor was observed. Cheddar cheese made from FM milk ripened faster after 3 mo of ripening and developed a more desirable texture and stronger Cheddar flavor. The yield efficiencies for FM and control cheese, 94.4 (+/- 2.44 SE) and 96.4 (+/- 2.26 SE), respectively, were not different. Relative to controls, average fat globule size was smaller in FM milk and churning time of FM cream was longer. FM butter had softer texture and better cold spreadability, and butter oils from FM enriched milk had lower dropping points compared to control butter oil (average 32.89 versus 34.06 degrees C). These differences in physical properties of butter fat were greater than expected considering that iodine values were not different. This study demonstrates the feasibility of producing high quality products from milk naturally supplemented with FM, but the results also show that dietary changes affect processing properties.     

碱性蛋白酶水解对豆粕中大豆抗原蛋白的影响

大豆是八大食物过敏源之一,其中主要蛋白成分7S和11S球蛋白也是致敏性较强的抗原蛋白。本试验研究了豆粕在Alcalase酶水解过程中7S和11S两种大豆抗原蛋白的变化。结果表明,酶解10 min时7S伴球蛋白的α’、α和β亚基、酶解60 min时11S球蛋白的酸性亚基等主要抗原蛋白成分即被完全水解,同时新产生了23 ku和大量14 ku以下组分;酶解豆粕中95.1%的蛋白可溶于水,其中68.1%蛋白质可溶于三氯乙酸。