Evaluation of Harp Seal Gastric Protease as a Rennet Substitute for Cheddar Cheese

A crude preparation of gastric proteases from Harp Seal (Pagophilus groenlandicus) was found to coagulate milk over a wider pH range than porcine pepsin and had a higher ratio of milk clotting to proteolytic activity with hemoglobin at pH 1.8. Cheddar cheese prepared with seal gastric protease (SGP) gave significantly higher sensory scores than cheese made with calf rennet. Chemical analysis of the cheeses revealed a lower concentration of citrate-HCl soluble nitrogen and less free and peptide-bound amino acids in SGP cheese than in the cheeses made with calf rennet and Mucor miehei protease.     

Partial Purification and Characterization of Cathepsin D-Like and B-Like Acid Proteases from Surf Clam Viscera

Different proteases were isolated and purified from viscera of surf clam, Spisula solidissima. These proteases were similar to cathepsins D and B, with molecular weights of ?36,700 and ?17,400 daltons, respectively. Optimum activity of enzymes towards hemoglobin and casein occurred from pH 2.5–3.0 and temperature 44–46°C. Cathepsin D-like protease, a carboxyl protease, was insensitive to most protease inactivators, but extremely sensitive to pepstatin. Cathepsin B-like protease, a thiol protease, was activated by thiol-reducing agents and metal chelators, but was sensitive to many reagents such as iodoacetamide, Tosyl-phenylalanine chloromethyl ketone, Tosyl-lysine chloromethyl ketone, phenylmethanesulphonyl fluoride, leupeptin and heavy metals.     

Evaluation of Potassium Chloride as a Salt Substitute in Bread

Breads made with white flour and a mixture of wheat and white flours were commercially prepared using three different levels of NaCl and a 1:1 mixture of NaCl/KCl. The Na and K content was determined by flame photometry on the dry ash. The 0.75% NaCl and 1.0% KCl/NaCl treatments for both white and wheat breads were judged equally desirable. The Na:K ratios of the 0.75% NaCl and 1% NaCl/KCl white breads are 7.00 and 1.20 respectively. The Na:K ratios for the 0.75% NaCl and 1% NaCl/KCl wheat breads are 3.29 and 0.91 respectively. Breads containing 1.00% of a 1:1 mixture of NaCl and KCl are not significantly different in flavor than breads containing 0.75% NaCl but the KCl containing product has a much lower Na:K ratio.     

以大米淀粉为基质的脂肪替代品的制备研究

研究了以大米为原料制备脂肪替代品的工艺条件,并通过扫描电镜观察了脂肪替代品的表面结构.结果表明,制备脂肪替代品的工艺参数为:浆料质量分数18%,温度90℃,时间12 min,水解酶用量4.6～6.2 U/g.喷雾干燥条件为浆料质量分数15%,进风温度170～185℃,出风温度90℃.脂肪替代品的粒径范围为3.3～74.5 μm,平均粒径为21.4 μm.     

Enzymatically Modified Beef Tallow as a Substitute for Cocoa Butter

ABSTRACT: Dark "chocolate" samples were formulated with either cocoa butter (CB), randomized tallow (RT) made with Candida antarctica (SP 435) lipase, or a beef tallow: stearic acid structured lipid (SL) made by acidolysis using Rhizomucor miehei (IM 60) lipase. Fatty acid composition, thermal profile, solid fat content (SFC), hardness, and polymorphic structure were determined for the fats and/or "chocolate" samples. An accelerated fat bloom study was performed on the "chocolate" samples. Neither of the modified tallows had a detrimental effect on the crystallization of CB after proper tempering of the "chocolates." RT did not soften the "chocolate" and both of the modified lipids reduced bloom rates.     

亚硝酸盐新型替代物番茄红素的研究进展

亚硝酸盐作为一种传统发色剂广泛应用于肉制品中,由于其具有潜在的毒性,近年来各国科学家纷纷寻找安全、绿色的亚硝酸盐替代物。本文对番茄红素替代亚硝酸盐的研究进展进行综述,并提出未来的发展方向,旨在为亚硝酸盐新型替代物的研究提供一定的理论参考。     

企鹅珍珠贝全脏器的营养成分分析与评价

对企鹅珍珠贝全脏器的营养成分进行了分析和评价,主要对其一般营养成分、氨基酸组成、脂肪酸组成及其无机质含量进行了检测和营养学评价。结果表明:企鹅珍珠贝肉的蛋白质含量为81.1%(干基),蛋白质组成氨基酸总量为13.0%,必需氨基酸种类齐全,第一限制氨基酸是缬氨酸,氨基酸价为84.3;富含Glu、Asp和Gly等呈味氨基酸;游离氨基酸中牛磺酸的含量高达722mg/100g,占游离氨基酸总量的47.2%;脂肪含量较低,且以多不饱和脂肪酸为主,其EPA和DHA的含量分别为12.61%和30.28%;无机质含量丰富,尤其是微量元素Zn(435mg/kg)和Se(0.68mg/kg)。因此,企鹅珍珠贝是具有独特鲜味和较高营养价值的优质海产品。     

亚硝酸盐替代物--组氨酸发色作用的研究

采用组氨酸与血红蛋白形成配位复合物，替代亚硝酸钠的发色作用，研究了pH对配合物紫外吸收的影响，计算出配位平衡常数β，并通过不同温度下测定β值，求出反应的标准摩尔焓和标准摩尔熵，表明配位反应是熵、焓降低的过程。     

鱼明胶替代哺乳动物明胶的研究进展

明胶是胶原蛋白变性的产物,在食品、医药等行业具有很好的使用价值。市面上的明胶以哺乳动物明胶为主,然而,因动物源性病毒与宗教文化等问题而限制了其发展。鱼明胶不受以上因素的限制,与哺乳动物明胶有相似的功能特性,具有很好的开发利用价值。然而,鱼明胶的凝胶性和流变性弱于哺乳动物明胶,研究者采取多种方式修饰鱼明胶,以获得所需要的性能。本文阐述鱼明胶与哺乳动物明胶的性质差异,概述鱼明胶改性方法研究进展,为鱼明胶性质的改善提供参考。     

Protoporphyrin-IX as a Substitute for Nitrite in Cured-Meat Color Production

The iron-free heme derivative protoporphyrin-IX, was added to a cooked emulsified beef product to mimic the typical cured-color obtained with nitrite. Although the pigment was stable and could be recovered from the emulsion it imparted a purple hue as noted by visual observation and Hunterlab color values (L,a,b). The possible implications of this pigment as a meat colorant are discussed.     

D-乳糖醇代替异丙基-β-D-巯基半乳糖苷对重组蛋白诱导表达的影响

目的:用D-乳糖醇代替异丙基-β-D-巯基半乳糖苷(isopropyl-β-D-thiogalactoside,IPTG)作为诱导剂,诱导重组葡萄糖苷酶的表达。方法:首先通过单因素试验探讨D-乳糖醇浓度、诱导时间及诱导温度对重组葡萄糖苷酶表达的影响,从而确定最佳影响因素的水平值,然后在单因素试验的基础上采用三因素三水平的响应面法对重组葡萄糖苷酶表达进行优化分析,依据回归分析方法确定最佳诱导工艺条件。结果:最佳诱导工艺条件为D-乳糖醇的诱导终浓度1.0 mmol/L、诱导时间7.0 h、诱导温度34℃。结论:D-乳糖醇可以代替IPTG作为一种高效的lac及其衍生物的启动子基因工程重组蛋白的理想诱导剂。     

植物油脂替代动物油脂 在再制奶油干酪中的应用

以奶油干酪为基料,研究不同植物油脂替代动物油脂在再制奶油干酪中的应用。测定干酪样品的质构、色度、油脂析出性、融化性及感官评定,并进行比较分析。实验结果表明,添加橄榄油和小麦胚芽油的干酪硬度和涂抹性与对照组相近(P>0.05);添加橄榄油、小麦胚芽油、油茶籽油和米糠油的干酪粘聚力与对照组接近,减少了15.23%~26.68%;添加橄榄油和油茶籽油的干酪粘合性与对照组相差19.68%、33.16%,差异显著(P<0.05)。添加油茶籽油、橄榄油、米糠油、小麦胚芽油和亚麻籽油的干酪色度与对照组十分相近(P>0.05)。在油脂析出性上,添加玉米油、米糠油、橄榄油、油茶籽油和南瓜籽油的实验组品质均得到了改善。添加橄榄油、亚麻籽油的样品组在融化性能上与对照组差异不显著(P>0.05),仅减少了1.15%和1.85%。添加油茶籽油、橄榄油、小麦胚芽油的样品组受到认可,得分高于对照组。综上,橄榄油组与对照组在各项指标上相似度最高,是较好的替代油脂。     

源于淀粉和纤维素替代材料的4类绿色环保餐具评价

为了比较源于淀粉和纤维素替代材料的环境绩效,以餐饮外卖领域推广使用的生物基餐具(复合淀粉基材料、覆膜纤维基材料)与可降解塑料餐具(全淀粉材料、全纤维材料)为研究对象,分析产品生命周期中的各种资源、能源消耗和环境排放并评价其环境影响。以1000个外卖食品餐盒为基准流,利用环境评估软件建立绿色环保餐具的生命周期评价LCA模型。结果表明,源于淀粉的绿色餐盒碳排放和能量消耗主要集中于原料获取和废弃物处理两个阶段,源于纤维的绿色餐盒碳排放和能量消耗则主要集中在制品生产阶段。全淀粉可降解餐具的各项环境影响指标最低,其中累计释放CO239.91kg,消耗电能332.04 MJ,较全纤维可降解餐盒碳排放降低69.5%,节约电能416.23 MJ。     

Characterization and Utilization of Dehydrated Wash Waters from Clam Processing Plants as Flavoring Agents

Wash water (WW) samples were collected from three clam plants (A, B, and C) during various processing stages, spray- and freeze-dried, analyzed for proximate composition, mineral and amino acid content and volatile flavor profiles. Selected WW samples were evaluated for possible incorporation into clam dips in place of clam meat and juice. Glucose accounted for more than 75% of total carbohydrate in selected WW samples. Glutamic acid, aspartic acid, glycine and alanine were the major amino acids in some of the selected WW of three clam plants. Selected freeze-dried WW samples may be added at 1.75% (w/w) to clam dip in place of clam meat and juice without any significant changes in overall acceptability, taste, odor, texture and appearance.     

鲍内脏多糖的抗氧化活性

为研究鲍内脏多糖的抗氧化活性,采用体外抗氧化实验,评价不同化学组成的鲍内脏多糖对1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基和·OH的清除作用,并以人体肝细胞LO2建立过氧化氢损伤模型,探讨鲍内脏多糖在细胞水平的抗氧化能力。结果表明:鲍内脏多糖CAVP、AVP1、AVP2具有良好的清除体外自由基能力。多糖CAVP、AVP1、AVP2清除DPPH自由基的半抑制率浓度(half maximal inhibitory concentration,IC50)分别为1.46、1.74、1.55 mg/m L。其清除·OH的IC50分别为7.14、15.27、8.11 mg/m L。另外,细胞模型法评价结果显示,鲍内脏多糖CAVP、AVP1、AVP2在质量浓度0.5~4.0 mg/m L条件下对肝细胞LO2的H2O2氧化损伤有保护作用,3种多糖样品均能显著提高LO2细胞存活率;CAVP(4.0 mg/m L)、AVP1(0.5 mg/m L)和AVP2(0.5 mg/m L)能极显著降低氧化损伤时乳酸脱氢酶的释放;CAVP能极显著提高LO2细胞内谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)(4.0 mg/m L)、过氧化氢酶(catalase,CAT)(0.5 mg/m L)、超氧化物歧化酶(superoxide dismutase,SOD)(0.5 mg/m L)活力;AVP1质量浓度为4.0 mg/m L时,能极显著提高LO2细胞内GSH-Px、SOD活力,显著提高CAT活力;AVP2分别在质量浓度0.5、4.0 mg/m L时极显著提高LO2细胞内CAT活力;在质量浓度为4.0 mg/m L时,3种多糖样品对降低细胞氧化损伤产生的丙二醛(malondialdehyde,MDA)均有显著作用。因此,鲍内脏多糖是一类潜在的抗氧化物,可用于此类功能食品的开发。     

单环刺螠废弃内脏中粗多糖的提取工艺优化

利用热水浸提的方法进行单环刺螠（海肠）废弃内脏中多糖的提取。采用单因素试验和L₉（3⁴）正交试验设计,研究不同pH值、料液比、提取时间和提取温度对单环刺螠内脏多糖提取率的影响。并采用Fenton体系测定单环刺螠内脏多糖对羟自由基（·OH）的清除作用。单环刺螠内脏多糖提取的最佳工艺条件为pH10、料液比1:40（g/mL）、时间3h、温度60℃。单环刺螠内脏多糖在质量浓度为50μg/mL时,对羟自由基清除能力可达60%,且具有剂量效应。     

Characteristics of Miniature Cheddar‐Type Cheese Made by Microbial Rennet from Bacillus amyloliquefaciens: A Comparison with Commercial Calf Rennet

Miniature Cheddar‐type cheeses were produced using microbial rennet from Bacillus amyloliquefaciens (milk‐clotting enzyme [MCE]) or calf rennet (CAR). With the exception of pH, there were no significant differences in gross composition between MCE‐cheese (MCE‐C) and CAR‐cheese (CAR‐C). The pH value of CAR‐C was significantly higher than that of MCE‐C at 40 and 60 d of ripening. The total nitrogen content of the pH 4.6‐soluble fraction obtained from MCE‐C was higher than that obtained from CAR‐C. However, nitrogen content of the 12% TCA‐soluble fraction was similar between CAR‐C and MCE‐C. The extent of α_s1‐casein and β‐casein hydrolysis, measured by urea‐PAGE, was similar in both cheese samples. The hydrolysis of β‐casein was lower than that of α_s1‐casein. Different reverse phase‐high‐performance liquid chromatography peptide profiles of ethanol‐soluble and ethanol‐insoluble fractions were obtained from CAR‐C and MCE‐C. The peptide content in the 2 cheese samples increased throughout ripening; the ratio of hydrophobic to hydrophilic peptides was lower in MCE‐C than in CAR‐C. Compared with CAR‐C, MCE‐C was softer as a result of higher protein hydrolysis. Microbial rennet from B. amyloliquefaciens contributed to higher proteolytic rates, which reduced ripening time.     

大曲丢糟代替米糠生产小曲的效果研究

通过对曲酒丢糟代替米糠生产小曲的效果研究,并对影响小曲出酒率和品质的工艺条件(培曲时间、温度)作了深入的探讨。确定了丢糟的最佳加入量为10%;培曲的时间是5d,温度是26℃。     

基于体外化学与细胞模型评价鲍内脏肽粉的抗氧化活性

本文考察了鲍内脏肽粉对二苯基苦基苯肼自由基(DPPH·)、羟自由基(·OH)、超氧阴离子自由基(O_2-·)的清除能力,结果发现,鲍内脏肽粉对DPPH·、·OH和O_2-·自由基具有一定的清除能力,其IC50值分别为0.87 mg/m L、7.53 mg/m L和19.41 mg/m L。采用H_2O_2建立体外培养人肝癌细胞(HepG2)氧化应激损伤模型,将细胞分为正常对照组,模型组、H_2O_2加低(1.6 mg/m L)、中(3.2mg/m L)、高(6.4 mg/m L)剂量组,检测各组细胞存活率、总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)活力、丙二醛(MDA)含量。结果发现,1.6 mg/m L、3.2 mg/m L和6.4 mg/m L 3个剂量水平的鲍内脏肽粉能显著提高HepG2细胞的存活率、T-AOC和SOD活力,显著抑制细胞的MDA含量,且剂量-效应关系明显,对H_2O_2氧化损伤HepG2细胞均具有一定的修复作用。结果表明,鲍内脏肽粉具有较好的抗氧化活性。