Autolysis and the endogenous proteinases characterised in beardless barb (Anematichthys apogon) muscle

Beardless barb is a common fish species used in fermentation of fish paste Ka-pi-plaa. Autolytic profile of beardless barb muscle showed the maximum autolysis was at 50 °C, at both acidic and alkaline pH values. With augmentation concentration of NaCl, autolytic activity slightly decreased. Endogenous proteinases isolated from fish muscle in crude extract forms were also characterised. The acidic proteinases had optimum activity at pH 3.0 and 50°C, and they showed higher proteolytic activity than the alkaline proteinases which were optimally active at pH 9.0 and 50 °C. Proteinases in peak at pH 3.0 were inhibited by pepstatin A, but those in peak at pH 9.0 were highly inhibited by PMSF, TLCK and soybean trypsin inhibitor, suggesting that both aspartic and serine proteinases were existed in beardless barb muscle. The proteinases were stable in pH range of 2.0-5.0 but unstable at the temperatures higher than 40 °C. NaCl suppressed the proteolytic activity, ATP activated the proteinase activity, while CaCl₂, MgCl₂ and CoCl₂ exhibited no influence on the activity. The results implied that cathepsin D is the predominant proteinase responsible for autolysis in beardless barb. The findings were useful to improve the processing and qualities of Ka-pi-plaa product using beardless barb as raw material.     

高温季节食醋生产中影响酒精发酵的因素及改进措施

该文以镇江香醋生产为例，分析了高温季节食醋生产过程中影响酒精发酵的因素，并提出了改进措施。     

Microbiological safety of kinema, a fermented soya bean food

Kinema is a fermented soya bean food of Nepal and the hilly regions of North-eastern States of India. Generally, the fermentation is dominated by Bacillus spp. that often cause alkalinity and desirable stickiness in the product. The present study was undertaken in a limited number of commercial (market) kinema samples to test for the presence of foodborne pathogens and their properties. Bacillus cereus was present in numbers exceeding 10⁴ cfu/g product in five of the tested 15 market samples. Enterobacteriaceae and coliform bacteria exceeded 10⁵ cfu/g in 10 of the 15 samples. Escherichia coli exceeding 10⁵ cfu/g was found in two samples. Staphylococcus aureus was not detected in any of the tested samples. Of 31 isolated typical and atypical strains of B. cereus, 18 representative strains were tested qualitatively for the ability to produce diarrhoeal type enterotoxin (BCET) using an Oxoid BCET-RPLA test kit. Overall, BCET was formed by 12 strains in BHIG (brain heart infusion broth +1% glucose), by seven strains on sterilized cooked rice, and by five strains on sterilized cooked soya beans. Semi-quantitative tests on BCET revealed that levels exceeding 256 ng/g soya beans, produced by single pure culture inoculation with the isolated B. cereus strains, were reduced to ≤ 8 ng/g by frying kinema in oil, a common procedure when making kinema curry. It was also shown in a mixed pure culture experiment that a kinema strain B. Subtilis DK-W1, is able to suppress growth and BCET formation by a selected toxin producing strain (BC7-5) of B. cereus. It is concluded that the traditional way of making kinema and its culinary use in curries is safe. However, for novel applications of kinema, safety precautions are advisable.     

Current Perspectives on the Physiological Activities of Fermented Soybean-Derived Cheonggukjang

Cheonggukjang (CGJ, fermented soybean paste), a traditional Korean fermented dish, has recently emerged as a functional food that improves blood circulation and intestinal regulation. Considering that excessive consumption of refined salt is associated with increased incidence of gastric cancer, high blood pressure, and stroke in Koreans, consuming CGJ may be desirable, as it can be made without salt, unlike other pastes. Soybeans in CGJ are fermented by Bacillus strains (B. subtilis or B. licheniformis), Lactobacillus spp., Leuconostoc spp., and Enterococcus faecium, which weaken the activity of putrefactive bacteria in the intestines, act as antibacterial agents against pathogens, and facilitate the excretion of harmful substances. Studies on CGJ have either focused on improving product quality or evaluating the bioactive substances contained in CGJ. The fermentation process of CGJ results in the production of enzymes and various physiologically active substances that are not found in raw soybeans, including dietary fiber, phospholipids, isoflavones (e.g., genistein and daidzein), phenolic acids, saponins, trypsin inhibitors, and phytic acids. These components prevent atherosclerosis, oxidative stress-mediated heart disease and inflammation, obesity, diabetes, senile dementia, cancer (e.g., breast and lung), and osteoporosis. They have also been shown to have thrombolytic, blood pressure-lowering, lipid-lowering, antimutagenic, immunostimulatory, anti-allergic, antibacterial, anti-atopic dermatitis, anti-androgenetic alopecia, and anti-asthmatic activities, as well as skin improvement properties. In this review, we examined the physiological activities of CGJ and confirmed its potential as a functional food.     

发酵种泥的投加对新鲜剩余污泥发酵产酸的影响

为进一步提高剩余污泥厌氧发酵产短链脂肪酸(SCFAs)的效率,将p H=10下长期(90 d)厌氧发酵的种泥接入至新鲜剩余污泥考察其对新鲜剩余污泥厌氧发酵产酸的影响.实验在2种p H条件下进行:不控制p H(p H=7.4±0.2),一组反应器中投加新鲜剩余污泥,并接种厌氧发酵种泥,另一组反应器只投加新鲜剩余污泥;控制p H为碱性(p H=10±0.2),一组反应器中投加新鲜剩余污泥,并接种厌氧发酵种泥,另一组反应器只投加新鲜剩余污泥.结果表明:相同p H条件下,接种厌氧发酵种泥反应器中的最大产酸量较不接种分别提高4.9(p H=7.4±0.2)和16.4 mg/g VSS(以COD计)(p H=10±0.2);同时接种发酵污泥、剩余污泥在p H=10±0.2下的最大产酸量较p H=7.4±0.2下的最大产酸量高146.2 mg/g VSS;碱性条件、不接种发酵种泥的产酸量较不控制p H、接种发酵种泥的高129.8 mg/g VSS.投加发酵种泥可提高新鲜剩余污泥厌氧发酵过程中SCFAs的产生效率;碱性条件与厌氧发酵种泥对新鲜剩余污泥发酵产酸具有协同促进作用;与接种发酵种泥相比,碱性条件对新鲜剩余污泥厌氧发酵产酸促进能力高.     

苹果梨醋发酵过程中醋酸发酵条件的优化

以甲酚紫培养基中加入乙醇作为分离培养基,从5种水果样品中分离得到20种醋酸菌,然后通过产酸量的测定,筛选出了一株产醋酸度高的醋酸菌AAB13.探讨了乙醇浓度、菌株接种量、发酵液有效体积对醋酸发酵的影响,并在优化的条件下制备了苹果梨醋.     

不同微生物发酵剂及木醋液在草炭发酵中应用效果研究

草炭与硬杂木锯末以2．6：1比例混匀后，接种不同微生物发酵剂和喷施500倍木醋液，在温室里容积为2．5m^3的发酵槽中进行对比试验，试验结果：喷施500倍木醋液比对照最高发酵温度高7℃，平均发酵温度高4℃；大于40℃以上中高发酵温度多7天；HA总比对照增加11．47％，HA游含量也略高于对照。在只接种微生物发酵剂的处理中，最高发酵温度是酵素菌56℃〉高温纤维分解菌55℃〉秸秆速腐剂54℃〉EM53℃〉对照46℃；在喷施木醋液条件下接种发酵剂，最高发酵温度是高温纤维分解菌57℃=酵素菌57℃〉速腐剂50℃〉EM48℃。HA总及HA游含量也是高温纤维分解菌＋木醋液与酵素菌＋木醋液两个处理明显高于对照及其他接种剂处理。