芹菜汁酸豆奶的研制

探讨了芹菜汁酸豆奶的工艺,并采用正交试验确定芹菜汁酸豆奶的最佳发酵条件,结果为：保加利亚乳杆菌（Lactobacillus bulgaricus）嗜热链球菌（Streptococcus thermophilus）=1：1,接种量为4%,芹菜汁添加量为10%,脱脂乳粉的添加量10%,发酵温度40℃,发酵时间5h.     

乳酸菌胞外多糖的生理功能及其在发酵乳中的应用

乳酸菌胞外多糖在现代生活的许多领域发挥着重要的作用,具有抗肿瘤活性、免疫调节活性等方面的生理功能,在乳酸菌胞外多糖的生理功能及其在发酵乳中的应用方面进行了概述.     

新疆传统发酵酸驼乳中乳酸菌的分离和鉴定

利用MRS琼脂培养基对新疆传统发酵酸驼乳中的乳酸菌进行分离,分别挑取可疑菌落进行革兰氏染色,对镜检结果为革兰氏阳性菌,且细菌形状为球状和杆状的两种菌种进行糖发酵实验与生物化学鉴定.结论是:在两种不同pH值的MRS琼脂培养基上,菌落为灰白色、有透明圈,分别呈球状和杆状的两种菌种为乳球菌和乳杆菌.     

乳酸发酵型百合乳饮料工艺的研究

研究了以百合酶解液、鲜牛奶为主要原料，生产出一种纯天然保健乳饮料的工艺，并对加工过程中的护色、酶解和稳定剂的选择等进行了探讨，最终确立了产品的最优配方和生产工艺。     

GROWTH OF STAPHYLOCOCCUS AUREUS AND ENTEROTOXIN A PRODUCTION IN FOODS CONTAINING POLYPHOSPHATES

Effects of pyro-, tripoly- and hexametaphosphates (0.5 and 1%, w/w) on growth of Staphylococcus aureus strain 196E and enterotoxin A (SEA) production were studied in cooked custard and beef at 22 and 30°C. No effect was observed in custard, where cell numbers/g increased from 10³ to 10⁸ and SEA reached 4.2 ng/g after 48 h at 22°C, irrespective of treatment. Cell numbers in cooked beef were ca. 10⁹/g after 48 h, and reduced numbers (by 1.5–2 log cycles) were found in samples containing 0.5 and 1% pyrophosphate during incubation at 22%, but not at 30°C. SEA concentrations in beef were 28 ng/g after 48 h at 22°C, and 93 and 184 ng/g after 24 and 48 h, respectively, at 30°C. SEA concentration correlated with amount of growth, and was nondetectable when cell numbers were ± 10⁶/g. Reduction of the meat pH by sodium acid pyrophosphate contributed to the observed inhibitory effect.     

STABILITY OF MILK FAT-WATER EMULSIONS CONTAINING SINGLE AND BINARY EMULSIFIERS

SUMMARY —The stability of 25% milk fat-water emulsions containing sorbitan-fatty acid emulsifiers were compared to determine the influence of single vs. binary emulsifier systems, and saturated vs. unsaturated emulsifier side chains. These variables were compared at emulsifier HLB values of 9.5–10.0 and at usage levels of 0.5–2.0% of the fat. There were no statistical differences (P > 0.05) between single and binary emulsifier mixtures or between emulsifiers with saturated or unsaturated side chains. There also was no significant difference (P > 0.05) between emulsifier HLB numbers of 9.5 and 10.0. However, as the amount of emulsifier in the system was increased the stability of the emulsion increased (P < 0.01).     

THE EFFECT OF STORAGE TEMPERATURE ON BACTERIAL GROWTH AND LIPOLYSIS IN RAW MILK

The temperature at which raw milk was stored, within the range 4°-8°C, affected the rate of growth of bacteria and the release of free fatty acids. The effects were of both statistical and practical significance and it was shown that, by maintaining milk temperatures at 4°C, a useful extension of the storage time of raw milk could be achieved. Lipolysis in stored milk was not closely related to the total concentration of psychrotrophic bacteria, but lipolytic rancidity was not observed when the psychrotroph count was below 5 × 10⁶ colony forming units/ml.     

AMINO ACID COMPOSITION AND NUTRITIONAL IMPLICATIONS OF MILK FERMENTED BY VARIOUS LACTIC CULTURES

A total of nine milk products were analyzed for total and free amino acids and total and nonprotein nitrogen. The products were: (1) whole milk (WM), (2) skim milk (SM), (3) WM fermented by Streptococcus thermophilus, (4) SM fermented by S. thermophilus, (5) WM fermented by Lactobacillus bulgaricus, (6) SM fermented by L. bulgaricus, (7) WM fermented by L. acidophilus, (8) SM fermented by L. acidophilus and (9) commercially prepared buttermilk. Essential amino acid content of the fermented milk was lower than that of the whole or skim milk. Fermentation of milk by lactic cultures decreased the total lysine (except butter milk) and methionine contents of all the samples. Since these two amino acids are limiting amino acids in protein malnourished areas, lactic fermentation of milk may be undesirable based on the chemical scores of the protein. However, the free amino acid content, including that of lysine and methionine, increases significantly upon lactic fermentation of milk. This predigestion of protein might result in an increased availability of the amino acids to offset the reduction in amino acids during fermentation and may even result in a better quality protein. Biological evaluation of the fermented milk proteins is necessary to evaluate their nutritional quality. L. bulgaricus was the most proteolytic of all the organisms used.     

干酪乳杆菌LC-15发酵乳血管紧张素转换酶体外抑制活性的研究

血管紧张素转换酶抑制剂筛选模型是一个用于抗高血压药物和功能性食品研究的有效模型。通过考察乳酸菌蛋白质水解能力与ACE抑制活性的关系，以一株具有较高ACE抑制活性的干酪乳杆菌LC-15为研究对象，研究了发酵时间、添加酪蛋白、酶水解处理和模拟胃肠消化对LC-15发酵乳的ACE抑制活性的影响。结果表明，乳酸菌对牛乳蛋白质的水解能力与ACE抑制活性呈现一定的正相关关系；干酪乳杆菌LC-15在复原脱脂乳中发酵至42h时，发酵乳的ACE抑制活性达到最高，此时ACE抑制率为66％；通过在复原脱脂乳中添加4％酪蛋白可以使LC-15发酵乳的ACE抑制活性提高到81％；控制复原脱脂乳水解度为10％，然后再利用LC-15进行发酵得到的发酵乳的ACE抑制活性达到85％；在模拟胃肠环境消化条件下LC-15发酵乳的ACE抑制活力从最初的85％下降到78％。     

野蓝莓、荞麦酸豆乳的研制

以大豆为主要原料，添加一定量的脱脂奶粉及荞麦糊等原、辅料，采用保加利亚乳杆菌与嗜热链球菌1：1混合（sL）、两歧双歧杆菌（Bb）、嗜酸乳杆菌（La）四种乳酸菌进行发酵。发酵后用野蓝莓（笃斯越橘）果酱调配制成酸甜可口、风味浓郁的营养保健型酸豆乳。通过正交试验确定最佳工艺条件为：豆水比1：10，以此原料豆乳为基数，菌种配比SL：Bb：La为2：1：2，接种量3％，发酵时间6h，发酵温度37℃；各种辅料添加量为：荞麦糊5％，野蓝莓果酱10％，蔗糖6％，乳糖2％，稳定剂0．2％，脱脂奶粉5％。     

嗜酸乳杆菌在果蔬发酵汁中的生长和存活模式研究

研究了嗜酸乳杆菌在果蔬发酵汁中的生长和存活模式.采用嗜酸乳杆菌进行单一果蔬汁及果蔬牛乳混合汁发酵制作果蔬发酵饮料.发现其生长基本遵循微生物生长规律,并且在4℃下贮藏时,发酵液中活菌数受低温,酸度,营养多重因素的影响.     

INFLUENCE OF ANTIMICROBIAL COMPOUND(S) EXTRACTED FROM MILK FERMENTED BY STREPTOCOCCUS THERMOPHILUS ON KEEPING QUALITY OF MEAT AND MILK

The potential of a methanol-acetone (M-A) extract prepared from milk fermented by Streptococcus thermophilus in extending the shelf-life of meat and milk was investigated. In experiment I, increasing amounts (0, 0.1, 0.2 and 0.3 ml) of M-A extract with or without ascorbic acid were added to 20 g aliquots of ground beef subsequently stored at 5–7° C for 0, 3 and 6 days. Total and gramnegative bacterial counts and pH in ground beef treated with M-A extract were significantly (P<0.01) less than the corresponding values in control beef on days 3 and 6 for all dose levels tested with significant (P<0.01). In experiment II, rib-eye steaks were sprayed with H₂O or 0.1, 0.2 and 0.3 ml of M-A extract and stored at 5–7° C for 0, 3 and 6 days. The total and gram-negative bacterial counts on the surface of steaks sprayed with M-A extract were significantly (P<0.01) lower than the counts in control steaks. Also, in experiment III, inhibition of bacterial growth by M-A extract was significant (P<0.01 or 0.05) both in milk stored at either room temperature or 5–7° C. M-A extract inhibited the growth of Pseudomonas fluorescens inoculated into milk.     

THE FUTURE OF UHT MILK AND MILK PRODUCTS IN EUROPE

The development of packed milk relative to total milk consumption in Switzerland from 1958-76 is illustrated and the future of the industry in Continental Europe considered. Decrease in milk consumption in both Switzerland and Germany and the limitations of climatic conditions and transport are discussed and the advantages of UHT long-life milk evaluated. The potential in an increasing market for UHT milk products and in aseptic filling machines is assessed. ( Editor's summary ).