Biodegradation Study on the Starch-LDPE Film by Soil Micro-organism

Abstract

Degradation of low density polyethylene (LDPE) film containing starch as the biodegradable additive has been studied by isolating a soil microbe identified as Pseudomonous species. The degradation of the film was monitored by mechanical property and the surface starch concentration by UV-spectrophotometry at different intervals of time. The degradation depends on the accessibility of starch i.e., the carbon source in the starch-LDPE film. By adding external carbon source like, monosaccharide and disaccharide sugars some changes in the rate of biodegradation was observed. The ultimate fall in tensile strength was higher for the film when exposed to a nutrient medium without any external carbon source. Mostly the added sugar helps in the growth of micro-organisms. Among the various external carbon sources, maltose was found to be the best. In case of maltose the loss of tensile strength was 50% in 58 days, but the film without additional sugar showed a fall in tensile strength of 48% in the same period.     

Bacterial Growth and Volatile Compounds in Yoghurt-Type Products from Soymilk Containing Bifidobacterium ssp

The growth of bacteria normally used to produce yoghurt was compared in soymilk and cow milk. Whether or not Bifidobacterium ssp. was present, fermented soymilks [soyoghurt (S), soyoghurt + bifi-dobacteria (SB)] were less acidic than fermented cow milks [yoghurt (Y), yoghurt + bifidobacteria (YB)]. When bifidobacteria were present (in SB), streptococci were more numerous than lactobacilli. Bifidobacteria in YB stimulated maximal growth of both yoghurt bacteria. In comparison to nonfermented milks, acetaldehyde and diacetyl increased in all cultures. Ethanol increased only in S/SB and acetone was detected only in Y/YB. Quantities of volatile products in Y/'YB were slightly lower than those in Y/S. In all cultures, n-hexanal was almost totally absent.     

Degradation characteristics of isolated and in situ cell wall lucerne pectic polysaccharides by mixed ruminal microbes

Two pectic polysaccharide fractions were isolated form lucerne (Medicago sativa L) leaves and used in fermentation experiments with mixed ruminal microbes. Both fractions were similar in chemical composition, containing galacturonic acid (52-58 mol%) and the neutral sugars arabinose (14-18 mol%), galactose (6-8 mol%) and rhamnose (8-12 mol%). Fermentation of both fractions was rapid and complete with a half-life of approximately 4 h. Production of total volatile fatty acids matched the degradation profile reaching a maximum level shortly after the rate of degradation began to decrease. The fermentation characteristics of citrus pectin and polygalacturonic acid were similar to those of the lucerne pectic fractions but galacturonic acid was much slower in its rate of degradation while soluble arabinogalactan from larchwood was virtually undegraded. Leaves of early bud stage lucerne and lower nodes and internodes of stems from full bloom lucerne were also fermented by mixed ruminal microbes. Pectic polysaccharides were rapidly and extensively degraded from both tissues. Initial rates were faster for leaves than for stems and the extent of pectic degradation was greater in leaves (8% residual) than in stems (17% residual). Selection of forage lines with increased pectic polysaccharides would provide greater amounts of rapidly available energy that could result in more efficient utilisation of the rapidly degraded protein in lucerne.     

Microbial and Oxidative Changes in Low-Fat Ground Beef During Simulated Retail Distribution

A low-fat ground beef product containing water, carrageenan, encapsulated salt and hydrolyzed vegetable protein (carrageenan-based) was compared to a low-fat, all-beef control during simulated commercial manufacturing and retail distribution. Few differences were found in oxidative stability and microbial growth of the two. No differences (P>0.05) were found in aerobic plate counts, populations of psychrotrophs or mold and yeast populations for the two products. Hunter color ‘a’ values (redness) and overall color scores for surface color were higher (P<0.05) for the carrageenan-based product than the all-beef product. Retail display of low-fat products in aerobic packaging resulted in greater (P<0.05) product discoloration than anaerobic retail display.     

Sodium Lactate Affects Pathogens in Cooked Beef

Cooked, quartered beef top rounds containing either 1, 2, 3 or 4% sodium lactate were aseptically sampled and slice sections were inoculated with Listeria monocytogenes (ATCC 43256), Staphylococcus aureus (ATCC 27154), Salmonella typhimurium (ATCC 13311), Clostridium perfringens (ATCC 12924), or Escherichia coli O157:H7 (ATCC 43895). Inoculated slices were stored at 10°C for 0. 7. 14. 21 or 28 days.‘Three and 4% sodium lactate generally displayed lim-ited proliferation of S. typhimurium, L. monocytogenes and E. coli O157:H7 when compared with control roasts (0% sodium lactate) and roasts containing 2% sodium lactate.     

优质新型泸型大曲的研制及应用

从优质大曲中筛选出5株各具特色的优良功能菌，即糖化功能菌C－24和A2－3，发酵功能菌S2.10，生香功能菌R－3和S2.1182。将它们配制成复合菌种接入泸型大曲中，制成的新型泸曲无论是感官指标还是理化指标都明显优于对照，出酒率提高6.49%。     

Characterization of Minced Meat Extracted from Blue Crab Picking Plant By-Products

Blue crab meat was mechanically extracted from picking-room byproducts to produce the following minced meat yields: 3.18%, white; 10.71%, mixed; 6.39%, claw, and 2.62%, leg. Each meat had distinct visual, textural, and flavor attributes. Aerobic plate counts of unpasteurized minced meat ranged from 10⁵ to 10⁷ CFU/g. Extraction within 1.5 hours of picking or icing of by-products prior to mechanical extraction stabilized microbial levels. Meat pasteurized at 80.6°C darkened or blued significantly less than meat processed at 83.3°C. Addition of citric acid-phosphate buffer to meat pasteurized at 80.6°C further reduced darkening of meats.     

黄烷-3-醇类化合物在体内的吸收、代谢特征与机制研究进展

黄烷-3-醇类化合物是人类饮食中含量最丰富的膳食多酚之一,近年来,黄烷-3-醇类化合物备受关注,这主要是因为许多研究发现其与很多慢性疾病风险的降低和代谢综合征的缓解密切相关,但黄烷-3-醇类化合物在体内发挥的作用一定程度上取决于其被摄入后的吸收和代谢,尤其是肠道微生物的分解代谢。因此,本文将重点探讨黄烷-3-醇类化合物的吸收、代谢及其生物转化的途径,有助于揭示其在体内的生物学作用。     

新型动态固态生物发酵反应器的研究及应用进展

固态发酵是指微生物在没有或几乎没有游离水的固体湿培养基上的培养过程,它是白酒尤其是浓香型白酒的传统发酵特点之一。介绍了近年来基于传统的固态发酵酿造(主要是浓香型白酒发酵)而研制的新型动态固态生物发酵反应器的种类和优势,并对其应用于浓香型白酒发酵的研究现状和展望作了阐述。     

己酸菌液在浓香型白酒生产中的应用

采用公司自制的己酸菌功能茵液,应用于窖池养护、回窖发酵、串蒸提香以及制备调味酒等方面,并对应用结果进行了分析总结。结果表明,利用己酸菌功能茵液进行窖池的养护及其微生物复壮,能改善窖池,提高酒质;应用于回窖发酵、串蒸提香、调味酒生产等能明显提高产酒质量,增加经济效益。