豆乳和花生乳的乳酸发酵研究

使用MRS培养基分离乳酸菌；通过革兰氏染色、凝乳时间观察和产酸量分析，筛选出生长活力高，产酸能力强的2株酸乳生产菌株：SLlb和SLst。将其以1：1的比例、3％的接种量接入适宜浓度的豆乳或花生乳中，在42℃保温培养2h～3、5h，得到风味纯正、酸甜适口、组织状态较好的酸豆乳和花生酸乳。     

大豆小米复合乳的工艺研究

以大豆、小米为主要原料，采用正交试验确定了大豆小米复合乳的配方和加工工艺。该产品具有豆乳和小米的复合香味，营养价值高。     

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.     

IN VITRO STUDIES TO CONTROL THE GROWTH OF MICROORGANISMS OF SPOILAGE AND SAFETY CONCERN IN HIGH-MOISTURE, HIGH-pH BAKERY PRODUCTS

Initial agar plate studies were done to determine the effects of various levels (0 to 2,000 ppm) of potassium sorbate (KS) and sorbic hydroxamic acid (SHA) over a wide pH range (5 to 9) on the growth of microorganisms of spoilage and safety concern in high-moisture, high-pH bakery products. While growth of most microorganisms was inhibited for > 28 days on agar plates containing ∼1,000 ppm of KS at pH 5 and incubated at 30C, growth of all microorganisms occurred in plates at pH 7 and 9, regardless of the concentration of KS. SHA was equally effective at pH 5, however, it proved to be a more effective inhibitor against most microorganisms at higher pH (9).
Subsequent agar plate studies were done with water-ethanol (WE) and mastic oil-ethanol (ME) emitters. While WE emitters failed to control the growth of all microorganisms under investigation, ME emitters controlled the growth of most microorganisms, with the exception of Listeria monocytogenes, for ∼12 to 28 days on agar plates packaged in high-gas-barrier Cryovac or metallized bags, respectively. Inhibition was not simply due to the levels of ethanol, which ranged from ∼1.2 to 2.8% v/v, but rather, the mastic volatiles in the package headspace.
This study has demonstrated the potential of SHA and ME emitters to control the growth of several microorganisms of spoilage and safety concern in high-moisture, high-pH bakery products. However, the type of packaging material influenced the antimicrobial efficacy of this vapor-phase inhibitor.     

SURVIVAL AND GROWTH OF SELECTED MICROORGANISMS IN KHOA DURING PREPARATION AND STORAGE

The survival of Escherichia coli and Staphylococcus aureus during the production of khoa, a heat concentrated Indian milk-based product, was investigated. Heat processing of milk containing from 3.6 to 6.5% fat at either 63 or 73C eliminated all E. coli. Under similar processing conditions , S. aureus was recovered, but only when heated in milk at 63C containing 6.5% fat. Potassium sorbate (3000 ppm) appeared more effective in inhibiting the growth of selected yeast and molds in khoa at 7C, compared to ascorbic acid (3000 ppm). Reducing the water activity (a _w) of khoa from 0.97 to 0.93 did not appear to enhance the preservative effect. The reduction of E. coli or S. aureus in khoa during prolonged storage at 6–7C, was less than one log cycle, regardless of a _w or preservative type. Survival of S. aureus in khoa appeared to be enhanced with a decrease in a _w. The potential for pathogens to survive in khoa during processing should be taken into consideration when formulating heating protocols.     

EFFECT IN RATS OF PARTIAL REPLACEMENT OF COW'S MILK PROTEIN BY SUPPLEMENTARY NITROGEN

SUMMARY: A number of experiments studied growth of weanling rats and urinary nitrogen excretion in young adult rats when cow's milk protein was partially replaced by varying levels supplementary nitrogen. A mixture of nonessential L-amino acids (NEAA) or a mixture of diammoniumcitrate and glycine (DAC-Gly) was used as the source of nitrogen. Substitution of the 15% milk protein diet to the extent of 10% slightly reduced growth; significant growth reduction occurred with substitutions of 20% and greater. Fortification of the diets containing 10.5% milk protein and the supplementary nitrogen sources with sulfur amino acids did not restore growth the maximum rate obtained with the 15% milk protein diet. Additional supplementation with tryptophan further improved growth slightly but not to the maximum rate. Several other essential amino acids, alone or in combination, had no apparent effect. Based on urinary nitrogen excretion, comparable results were obtained with young adult rats by substituting nitrogen for milk protein the diets. The reduced performance following substitution of milk protein with supplementary nitrogen may be due partly to decreased utilization of sulfur amino acids and possibly to decreased utilization of all essential amino acids.     

EFFECTS OF GROWTH REGULATORS ON YIELD AND QUALITY OF MUNGBEAN SPROUTS GROWN IN AN AUTOMATICALLY CONTROLLED CHAMBER

High quality mungbean sprouts are characterized by thick hypocotyls and short roots. In this study, three plant growth regulators (gibberellic acid, ethephon and abscisic acid) were applied to mungbean sprouts during growth in a microprocessor controlled chamber. Ethephon and gibberellic acid treatments produced sprouts having substantially more food value (dry matter, protein, ascorbic acid) per 100 g of mungbeans than the nontreated controls. Single application (10 or 20 ppm) or double application (20 ppm) ethephon treatment improved mungbean sprout quality through its root-shortening and hypocotylthickening effects. The chamber developed in this study eliminated labor and provided a simple, convenient and reproducible sprout growing process. It has potential in small factories or restaurants as well as in the laboratory.     

黑豆多糖的提取工艺及稳定性研究

采用热水提取法来获得黑豆多糖,对其提取工艺进行优化研究,并探讨黑豆多糖的稳定性.结果表明提取的最佳条件为:料液比为1:20,提取温度为90℃.提取时间为4h.此条件下黑豆多糖的提取率为0.396%.黑豆多糖耐热性较差,稳定性受光照影响较小,耐氧化性较好,且不易被还原.pn值在5.0-7.0范围内,黑豆多糖有良好的稳定性.     

即食腐竹的保鲜研究

研究了山梨酸钾、对羟基苯甲酸丁酯、溶茵酶等几种防腐剂在即食腐竹中的保鲜效果。结果表明：单一防腐剂对即食腐竹的防腐效果不好，在37℃下，对羟基苯甲酸丁酯能使即食腐竹保存6d，山梨酸钾、溶茵酶能使即食腐竹保存9d；而根据多种防腐剂及辅助剂的互补增效作用研究出的复合防腐剂，则能使即食腐竹的保质期达到21d以上。