冷冻面团发酵技术在中式食品中的应用II．冰结构蛋白对鲜酵母及包子类冷冻面团流变发酵特性的影响

应用F3 流变发酵仪和动态流变仪研究冰结构蛋白(ISP)对冻藏0、1、2、3、4 周鲜酵母发酵特性和冷冻面团动态流变学特性的影响。结果表明：随着冻藏时间延长,所有酵母样品发酵过程中气体释放曲线最大高度H′m、产生CO2 气体总体积V总及面团最大膨胀高度Hm 均逐渐降低,冷冻面团的弹性模量(G′)和黏性模量(G 〞)逐渐下降,冷冻面团包子比容显著减小。引入冰结构蛋白(ISP)后,冻藏时间相同时,酵母发酵过程中的H′m、V 总及Hm 均有所增大,G′和G 〞下降趋势减缓,冷冻面团包子比容明显大于空白组,说明ISP 能够抑制冻藏过程中冰晶的形成和重结晶,减弱冰晶对酵母及面筋蛋白质网络结构的破坏,同时也说明ISP 能够增强面筋蛋白质网络结构的强度,提高面筋蛋白质对冰晶破坏的抵抗力。     

Microviscosity of togavirus membranes studied by fluorescence depolarization: influence of envelope proteins and the host cell

The microviscosities of the hydrophobic regions of the membranes of intact Semliki forest and Sindbis viruses grown on BHK-21 cells, of liposomes derived from the extracted viral lipids, and of protease-treated virions were measured by fluorescence depolorization using the fluorescence probe 1, 6-diphenyl-1,3,5-hexatriene. The intact virus membranes were found to have a higher microviscosity than did virus-derived liposomes, indicating the viral envelope proteins contribute to microviscosity. However, protease-treated virus, devoid of protruding spikes but with residual lipophilic peptide tails, was found to have a microviscosity more similar to that of the intact virus than to that of protein-free liposomes. Sindbis virus grown in BHK-21 cells at 37 C had a much higher microviscosity than did Sindbis virus grown on Aedes albopicuts cells at 22 C. Sindbis virus grwon in A. albopictus and BHK-21 cells also gave higher microviscosity values than did the intact host cells. These data indicate that both the virion proteins and the cellular lipids selected during viral growth and maturation contribute to the increased microviscosity of togavirus membranes.     

Factors affecting the uptake of 99mTc-sulfur colloid by the lung and kidney

Occasionally patients injected with 99mTc-sulfur colloid (TSC) for liver--spleen imaging show increased uptake by the lungs or kidneys. In animals, increased lung uptake of TSC can be produced by injecting endotoxin intraperitoneally. Using an intraperitoneal endotoxin model, we studied the effect of heparin on dose-response curves for TSC uptake by the lungs and kidneys. Over a dose range of 1 mug to 10 mg of endotoxin, TSC uptake by the lungs increased progressively; heparin had no effect. In the kidneys, endotoxin in doses from 1 mug to 1 mg resulted in an increased TSC uptake which was less marked than that in the lungs and which was also unaffected by heparin. However, at a dose of 10 mg of endotoxin, a marked increase occurred in TSC uptake by the kidneys, and this could be prevented by heparin. Although the increased TSC uptake by the kidneys at lower doses of endotoxin and by the lungs at all doses is probably not related to intraavascular coagulation, the marked increase in TSC uptake by the kidneys at 10 mg of intraperitoneal endotoxin probably is related to intravascular coagulation, possibly by entrapment in fibrin deposits in the renal capillaries.     

The effect of hypoxia on the regional distribution of cardiac output in the dog

Twenty-one dogs were studied under conditions of normal oxygenation and hypoxia with the microsphere distribution method to determine the effect of arterial oxygen saturation on the regional distribution of cardiac output. The dogs were anesthetized and artifically ventilated. Cannulas were placed in the left ventricle to administer microspheres and in a peripheral artery to determine cardiac output. Each dog received two microsphere injections: (1) while normally oxygenated (room air), and (2) under hypoxia (10% oxygen-90% nitrogen in 10 dogs and 5% oxygen-95% nitrogen in 11 dogs). Absolute cardiac output increased from 87 +/- 15 ml/min per kg to 101 +/- 14 ml/min per kg during mild hypoxia (10% oxygen) (P less than 0.05), and from 73 +/- 17 ml/min per kg to 120 +/- 24 ml/min per kg during severe hypoxia (5% oxygen) (P less than 0.01). Absolute blood flows increased to all organs except skin and muscle during hypoxia, although there were decreases in the fractional distribution of cardiac output to the splanchnic bed and kidney. Striking changes were found in coronary, hepatic, and cerebral circulation, and the organ with, greatest response to hypoxia was the heart, with increased coronary flow of 37% and 285% during exposure to 10% and 5% oxygen, respectively. Hence, low oxygen levels in blood cause redistribution of cardiac output and arterial content plays an important role in blood flow regulation.     

Growth and metabolic activity of a cheese starter in CO2-acidified and non-acidified refrigerated milk

 The growth and activity of two Lactococcus strains and one Leuconostoc strain in CO₂-acidified and non-acidified refrigerated milk were evaluated separately and as a mixed culture to determine their suitability for use as a starter in the manufacture of Afuega’l Pitu, an acid-coagulated Spanish cheese, from refrigerated CO₂-acidified milk. The growth of the strains studied and their production of organic acids were similar in CO₂-acidified and non-acidified refrigerated or fresh milk, indicating that CO₂ treatment does not affect the metabolic activity of the strains. However, refrigeration enhanced the production of acetaldehyde, ethanol and diacetyl in CO₂-acidified and non-acidified milk. The level of diacetyl was also greater in refrigerated CO₂-acidified milk than in refrigerated non-acidified milk. It was concluded that refrigerated milk acidified with CO₂ can be satisfactorily used in the manufacture of Afuega’l Pitu cheese, and that this technique can be also used in the production of other acid-coagulated cheeses. Received: 1 July 1997 / Revised version: 1 September 1997     

Influence of the number of distillations on the composition of organic sugarcane spirit

Sugarcane spirit is the most consumed distilled beverage in Brazil. Currently the manufacturing industries are trying to widen their market and attract new consumers, and thus it has become necessary to elevate the product to national and international quality standards. This study's aim was to determine the influence of subsequent distillations on the composition of organic sugarcane spirit. From mono‐distilled organic sugarcane spirit, bi‐, tri‐, tetra‐ and penta‐distilled sugarcane spirits were obtained, and analysed for the following: relative density, alcoholic degree, volatile acidity, pH, copper, methanol, aldehydes, furfural, esters, ethyl carbamate and higher alcohols. The most relevant results were reductions of 69.57% volatile acidity, 98.4% copper, 40.9% methanol, 71.5% aldehydes, 100% esters, 100% ethyl carbamate and 32.2% higher alcohols in the penta‐distilled sugarcane spirit, as compared with the mono‐distilled. It was concluded that subsequent distillations would put sugarcane spirit in line with the international standards for distilled beverages. Copyright © 2013 The Institute of Brewing & Distilling     

Local Notions of Healthy Eating and National Dietary Guidelines: A Comparison in Vulnerable Salvadoran Communities

This study presents an assessment of local definitions and perceptions concerning healthy eating through a study in four resource-poor border communities in El Salvador. The study included focus groups, key-informant interviews, and observations of the food environment. Local definitions of healthy eating elicited through focus groups were compared to the national Salvadoran dietary guidelines recommendations. The comparison revealed several areas of overlap (including the importance of dietary variety, fruits, and vegetables, among others) and omissions (mention of limiting sweets/candy, salt, sugar, and alcohol). Focus group participants expressed concerns over the origin of their foods and whether food contained harmful chemicals. These conversations also revealed the contradictions between nutrition knowledge and preferences for foods classified as unhealthy. This article concludes with a discussion about barriers to healthy eating identified in the focus groups and through the food environment assessment.