影响胃蛋白酶凝乳作用因素的研究

探讨了反应温度、滴定酸度、胃蛋白酶添加量、ＣａＣｌ２加入量等因素对胃蛋白酶凝乳作用的影响规律，确定了用胃蛋白酶生产干酪时的主要工艺参数，反应温度３９℃；滴定酸度２４Ｔ；ＣａＣｌ２加入量０．０１５％；加酶量随酶活而定。     

不同因素对羔羊皱胃酶凝乳活性的影响

研究结果表明，羔羊皱胃酶最适凝乳温度为45℃；35℃以上热处理对酶凝乳活性有不同程度的损失，60℃热处理10 min活性完全丧失；pH值为5～8时凝乳活性随乳pH值的降低而增强，酶在pH2.5～7.5之间处理20h凝乳活性稳定；Ca²⁺具有明显的促凝作用；底物浓度对酶活性的影响符合米氏规律。     

Micropropagation of Vegetable Rennet (Withania coagulans [Stocks] Dunal)—A Critically Endangered Medicinal Plant

Withania coagulans (Stocks) Dunal (Solanaceae), popularly called vegetable rennet, is a critically endangered and highly valued medicinal plant. Overexploitation and reproductive failure forced the plant species toward the verge of complete extinction. We describe here the development of a simple, rapid, and cost effective in vitro micropropagation system for W. coagulans for mass-scale production of true-to-type plantlets using nodal shoot segments. Exactly 95.5 ± 0.34% explants responded within 8–10 days (d) and produced multiple shoot buds (4.1 ± 0.10 shoots of 2.95 ± 0.15 cm length) on 0.8% agar-gelled Murashige and Skoog's (MS) basal medium supplemented with 8.88 μM 6-benzylaminopurine (BAP), 0.57 μM indole-3-acetic acid (IAA), and additives (100 mg L^?1 L-ascorbic acid, 25 mg L^?1 each citric acid, adenine sulphate, and L-arginine). The shoots in cultures were multiplied by repeated transfer on MS medium with 4.44 μM BAP, 0.57 μM IAA, and additives. Further cultures were multiplied on a large-scale through the subculturing of shoot clumps differentiated in vitro, on MS medium supplemented with 1.11 μM BAP, 0.57 μM IAA, and additives. Maximum number (19.1 ± 0.28) of healthy (6.15 ± 0.25 cm) and viable shoots differentiated on this medium. The microshoots were rooted both in vitro and ex vitro. Exactly 67.3 ± 1.01% microshoots rooted in vitro within 25–30 d on agar-gelled half-strength MS salts supplemented with 29.52 μM indole-3-butyric acid (IBA) and 200 mg L^?1 of activated charcoal (AC). Alternatively, 73.8 ± 0.65% cloned shoots rooted on sterile soilrite (soilless compost and soil conditioner) under ex vitro conditions after pulse treatment with 2.46 mM IBA for 300 s. The clones of W. coagulans were hardened in a greenhouse within 40–45 d by slow and gradual exposure of plantlets from high relative humidity (RH; 70–80%) and low (26 ± 2°C) temperature to low RH (40–50%) and high (34 ± 2°C) temperature. The hardened plantlets were transferred to soil and stored in agro-net house with more than 90% survival rate. Replacement of pure and laboratory grade sucrose with commercial grade sugar, use of less expensive commercial grade agar-agar in culture medium, higher rate of shoot proliferation, single step ex vitro rooting, and hardening of plantlets in the greenhouse are advantageous features of the protocol. The micropropagation protocol defined here is reproducible, easy to follow, and would be helpful in large-scale restoration programs through true-to-type mass-multiplication of W. coagulans.     

不同凝乳酶加工的羊奶干酪成熟期微生物变化

以西农莎能奶山羊的新鲜奶为原料 ,用微生物酶、牛皱胃酶和胃蛋白酶等 3种凝乳酶加工硬质干酪 ,检测其不同成熟期细菌总数、乳酸菌、大肠菌群、酵母和霉菌含量的变化 ,并对不同成熟期间的干酪进行感官综合评定。结果表明 ,微生物酶加工的干酪 ,在成熟第 60天其品质达到优良 ,而另 2种凝乳酶加工的干酪 ,在成熟第 90天其品质可定为优良。数据统计分析表明 ,不同凝乳酶加工的干酪 ,在其成熟期间各种微生物变化规律以及干酪品质明显不一致 ,并且干酪品质与微生物的数量和种类密切相关     

利用超声处理提取皱胃酶的试验研究

以1～2周龄小牛皱胃为原料，利用超声提取法研究了超声强度、提取时间、提取液NaCl浓度、皱胃与提取液比例以及提取液pH值对皱胃酶(rennet)提取活性的影响。试验结果表明，与传统提取法相比较，超声提取法可显著缩短提取时间和提高皱胃酶的活性，其最佳工艺参数为：超声强度40 W/cm²，提取时间70 min，提取液NaCl浓度10%，提取液pH值5.0；皱胃与提取液比例为1∶20。     

不同pH提取液对羔羊皱胃酶提取活性的影响

以关中奶山羊羔羊皱胃为原料,分别用pH4.5,5.4和6.0提取液提取羔羊皱胃酶,并用L9(34)正交试验研究了不同pH提取液对皱胃酶提取效果的影响。结果表明,pH5.4提取液的提取活性最高,pH6.0提取液次之,pH4.5提取液最低;其最佳技术参数为:提取液pH5.4,NaCl质量浓度80g/L,提取温度30℃,皱胃质量与提取液体积之比为1∶20;提取时间48h。     

地衣芽孢杆菌D3.11凝乳酶对切达干酪质地特性的影响

为揭示地衣芽孢杆菌D3.11凝乳酶对切达干酪成熟过程中质地的影响,利用地衣芽孢杆菌D3.11凝乳酶制作切达干酪(CDF组)和切达干酪类似物(CD3组),采用商品凝乳酶作为对照(CCF组),分析干酪成熟过程中质构、流变特性、微观结构的变化规律.结果表明:3组干酪的硬度随着干酪的成熟而增加,而弹性和咀嚼性则呈现下降趋势,C...     

切达干酪加工技术综述

介绍了内蒙古骑士股份有限公司切达干酪的生产经验和切达干酪的加工工艺,以及在生产中的关键控制点。对切达干酪的生产工艺在理论上进行了探讨。     

Kid depletion in mouse oocytes associated with multinucleated blastomere formation and inferior embryo development

This study investigated the knockdown (KD) of Kid on maturation developmental competence and multinucleation of mouse germinal vesicle (GV) oocytes after parthenogenetic activation. Data revealed that Kid messenger RNA (mRNA) was expressed in GV and MII stage oocyte and 1‐ and 2‐cell embryos. Additionally, Kid mRNA expression in the Kid KD group decreased by nearly 46% compared to the control small interfering RNA (siRNA) groups. The rate of multinucleated embryos in the Kid KD group (52.4%) was significantly higher (P < 0.05) than the control siRNA group (4.7%). Finally, the developmental rates were significantly lower in the Kid siRNA group at > 4‐cell stage (28.6% vs. 53.5%) and the blastocyst stage (2.4% vs. 23.3%) compared to the control siRNA groups. Suppression of Kid using siRNA caused multinucleation in early embryos with high frequency and it may increase 2‐ to 4‐cell arrested embryos and reduce the developmental competence to blastocyst.     

牦牛“曲拉”干酪素凝乳酶的选择及工艺参数优化

以“曲拉”为原料，研究不同酶在凝乳酶干酪素制作中的应用效果，通过L₉(3⁴)正交试验对皱胃酶、木瓜凝乳酶、微小毛霉凝乳酶3种酶最佳工艺参数进行筛选，结合生产成本，优选出微小毛霉凝乳酶为生产凝乳酶干酪素的酶制剂，其最佳工艺条件为酶浓度3.75 mL/g，pH 7，温度55℃，CaCl₂添加量12 g/kg。制品出品率73.49%，感官得分9.49，蛋白质含量85.25%，灰分7.23%，脂肪0.45%，符合QB/T3780-1999标准要求。