硅酸盐细菌发酵条件的优化

通过正交实验对硅酸盐细菌JXSD-18菌株的发酵条件进行了优化研究,结果表明,比较理想的发酵条件为:摇床转速200 r/m in,起始pH值7.0,温度32℃,装液量30mL,在此条件下硅酸盐细菌的溶磷效果达到最好。     

黑茶加工中微生物作用的研究

六堡茶、普洱茶、茯砖茶等同属黑茶类，传统加工过程中的渥堆发酵是形成黑茶品质特征的关键，上述过程需要微生物参与才使其具有独特品质。本文就黑茶生产过程中的主要微生物种类、微生物分泌的胞外酶及其对黑茶品质形成所起的作用、微生物的安全性进行综述。     

发酵豆粕的生产现状及产品质量评定研究

介绍了国内主要发酵豆粕厂家的生产工艺流程、产品质量评定指标及鉴别方法。     

不同添加剂对柱花草青贮品质的影响

以热研2号柱花草为原料， 通过直接青贮（CK）、 添加山梨酸（0.2％）、 蔗糖（2％）、 青贮宝（0.1％）等处理， 30 d后测定了柱花草青贮饲料pH值、 乳酸、 乙酸、 丙酸、丁酸等含量并分析其主要营养成分含量。结果表明： 柱花草直接青贮品质较差， 添加山梨酸、 蔗糖、 青贮宝等处理能降低pH值和提高乳酸含量， 添加2％蔗糖能极显著降低pH值(p<0.01)、 提高乳酸含量(p<0.05)， 改善青贮品质， 提高营养价值。     

灵芝多糖液体发酵条件优化

从一系列灵芝(Ganoderma sp.)菌种中筛选出多糖产量高、生长快的紫灵芝菌株(G.japoncium),研究了不同氮源、碳源及金属离子对紫灵芝产多糖的影响。结果表明,以2%的蔗糖为碳源,0.2%的豆饼粉为氮源,0.2%的FeSO4为培养基可获得较高多糖。发酵罐放大实验表明,采用同样的培养基,每100mL发酵液胞外粗多糖含量可高达181.7mg,每100mL发酵液菌丝体含量可高达151.0mg,发酵过程中pH值的变化比较缓和,相对摇瓶生长,发酵生产可获得更多的灵芝多糖。     

蘑菇培养料加入864菌液发酵与二次发酵的效果比较

通过加入８６４菌液发酵和二次发酵栽培蘑菇的试验,比较培养料中微生物群落、培养料成份及产菇量,说明加入８６４菌液发酵是代替二次发酵栽培蘑菇的较好方法。     

Optimization of Fermentation Medium for Cordyceps brasiliensis Using Response Surface Methodology

The composition of fermentation medium for producing Cordyceps brasiliensis mycelium was optimized using response surface methodology. A Plackett-Burman design was applied to screen potential key factors selected on the basis of preliminary experiments, and the steepest ascent method was adopted to approach the approximate optimal medium composition. Finally, central composite design and response surface methodology were applied to define more precisely the optimal composition of the fermentation medium. Our data revealed glucose and beef extract to be the most influential parameters, and the composition of the optimal fermentation medium (100 mL) was determined to consist of 4.46 g glucose, 2 g soluble starch, 4 g silkworm powder, 2.93 g beef extract, 0.10 g KH2PO4 and 0.15 g MgSO4·7H2O.     

Reduction of some toxicants in Icacina mannii by fermentation with Saccharomyces cerevisiae

The effect of fermentation on the level of some toxic components (hydrocyanic acid, phytic acid and oxalic acid) of Icacina mannii paste was investigated. The results indicate that fermentation caused a decrease in the level of these toxicants ranging from 178 mg/kg to 70 mg/kg for hydrocyanic acid, 638 mg/kg to 463 mg/kg for oxalic acid and 49 mg/kg to 21 mg/kg for phytic acid. When the paste was supplemented with acitve cells of Saccharomyces cerevisiae there was a marked decrease in the level of the three toxicants ranging from 84 mg/kg to 16 mg/kg for hydrocyanic acid, 374 mg/kg to 88 mg/kg for oxalic acid and 24 mg/kg to 5 mg/kg for phytic acid. Supplementing the paste with yeast cells at a concentration of 7.5 g/kg before fermenting, resulted in approximately a 90% reduction in the level of the three toxic compounds after 144 hours of fermentation.     

Preharvest and postharvest factors related to off-odours of fresh-cut iceberg lettuce

The influence of different preharvest and postharvest factors affecting off-odour development of fresh-cut iceberg lettuce in low-O₂ modified atmospheres (MA) was investigated. Fresh-cut iceberg lettuce developed undesirable off-odours under low O₂ and elevated CO₂ atmospheres. A strong relationship between CO₂ concentration and off-odour development was observed. Significant differences in off-odour development existed among different cultivars in two harvests in consecutive years. The influence of maturity stage was evaluated, comparing fresh-cut product from immature and over-mature heads with commercial ones. Higher CO₂ concentrations and higher accumulation of ethanol and acetaldehyde were detected in the headspace of MA-packed lettuce from immature heads. Differences in respiration rate of the fresh-cut product from heads cultivated during the winter–spring seasons were around 30%. Respiration rate of fresh-cut iceberg lettuce increased when medium temperature during cultivation increased. Changes in the product weight generated different CO₂ levels which correlated with the production of ethanol and acetaldehyde and other off-odour metabolites related with the lipoxygenase (LOX) pathway such as hexanal, 1-hexanol, and cis-3-hexen-1-ol. Volatile compounds such as cis-3-hexen-1-ol, β-elemene, ethyl acetate and dimethyl sulphide increased their content more than 10 times compared with other volatiles. Moreover, differences in the initial flushed gas-mixture with or without CO₂ showed higher CO₂ concentrations and the development of stronger off-odours when samples were flushed with an enriched CO₂ gas-mixture. In summary, visual quality of fresh-cut iceberg lettuce is important but so are odour and flavour. MAP currently used for fresh-cut lettuce may need some modification to inhibit off-odours and achieve better aroma and flavour qualities for preserving “freshness” of the cut product. Screening for cultivars with low browning potential and fermentation, harvested at optimum maturity stage and with an adequate package design are recommended.     

以油菜秸秆为主要原料的有机肥发酵工艺研究

采用堆肥工艺将农作物秸秆转化为有机肥还田是秸秆资源化利用的有效手段。本文以油菜秸秆为主要原料,通过添加腐熟菌剂及调节发酵原料组分,研究油菜秸秆腐熟发酵最佳工艺。结果表明:腐熟菌剂、碳氮比及氮源对油菜秸秆腐熟发酵影响显著,其中油菜秸秆添加腐熟菌剂和15%菜籽枯,发酵物料碳氮比为25∶1,堆肥效果较好,发芽率指数为73.5%。