对不同贮藏时间的鲜切淮山,采用3.0 kJ/m2剂量的短波紫外线(short-wave ultraviolet,UV-C)照射和质量浓度10 g/L壳聚糖涂膜处理,研究两种处理方法及二者协同作用对鲜切淮山生理指标的影响,探讨其保鲜效果及保鲜机理.结果表明,与对照组相比,UV-C处理鲜切淮山能够促进酚类物质和类黄酮类物质积累,增强抗氧化能力,抑制氧化损伤.壳聚糖涂膜鲜切淮山,主要通过抑制呼吸作用、降低细胞膜透性、降低细胞膜脂质过氧化而延长保鲜时间.当鲜切淮山贮藏达到12 d时,与对照组相比较,UV-C照射处理、壳聚糖涂膜、二者共同处理使呼吸强度分别降低15.7％、21.3％和23.6％,使菌落总数分别降低24.6％、18.5％和30.8％,使总酚含量分别增加13.3％、16.7％和22.2％,使1,1-二苯基-2-三硝基苯肼自由基清除率分别提高17.5％、9.6％和20.2％.由此可知,3.0 kJ/m2剂量的UV-C照射与质量浓度10 g/L壳聚糖涂膜对鲜切淮山均具有较好的保鲜效果,二者协同处理的保鲜效果更好,本研究可为鲜切果蔬的保鲜与贮藏提供借鉴.

对不同贮藏时间的鲜切淮山,采用3.0 kJ/m2剂量的短波紫外线(short-wave ultraviolet,UV-C)照射与质量浓度1.0％壳聚糖涂膜协同处理,研究两种保鲜方法对鲜切淮山营养品质的影响.研究发现,与对照组相比,在短波紫外线照射与壳聚糖涂膜保鲜处理过程中,鲜切淮山中的可溶性固形物、多糖、VC、淀粉、可溶性蛋白质均保持较高含量.研究表明,短波紫外照射与壳聚糖涂膜保鲜处理,有助于提升鲜切淮山的营养品质.

为了研究鲜切淮山的保鲜方法,保证其良好的感官品质,延长货架期,用不同剂量(0.5、1.0、1.5、3.0、4.5、6.0 kJ/m2)的254 nm短波紫外线分别照射60、120、180、360、540、720 s.通过测定色差值、褐变度、硬度及失重率探究其保鲜效果.研究发现:3 kJ/m2的照射剂量能明显抑制淮山的褐变,保持色差值L*和硬度,减小淮山切片的失重率,说明UV-C对鲜切淮山有明显的保鲜效果.

This paper discussed the current research status of acid-catalyzed hydrolysis of biomass-derived levulinic acid (LA) with 3 aspects i.e. sources of raw materials, catalytic mechanism and research progress. The method of preparing levulinic acid from furfuryl alcohol, carbohydrate represented by monosaccharide and sucrose, biomass represented by starch and cellulose were introduced. Meanwhile, the mechanism of preparing LA was analyzed, which provided reference for the study of levulinic acid.

Response surface methodology was used to optimize the parameter of pretrement on bagasse by ultra-sonic assisted NaOH and ammonia to produce xylose. The single-factor experiment was conducted to explore the effect of mixed double alkali concentration and ratio, ultrasonic time, ultrasonic power, ultrasonic temperature, ratio of solid-liquid on xylose concentration in bagasse hydrolysate. On this basis, optimization model was de-signed by Box-Behnken design and verification experiment was conducted to inspect comprehensive influ ence of 4 factors on xylose concentration. Optimized conditions was obtained:ratio of NaOH-ammonia was 2:1 (volume ratio), mixed double alkali concentration was 17％, ultrasonic temperature was 45℃, ultrasonic power was 300 W, ultrasonic time was 40 min. The xylose concentration of verifying result was 2.4310 g/L, which was consistent with the theoretical value of 2.5 g/L.

Application of microbial fermentation of xylose to produce xylitol can not only turn waste into useful products and conserve resources, but also protect the environment. Currently, more than 100 kinds of microorganisms are known to ferment xylose, among which Candida tropicalis has strong xylose conversion ability and high tolerance to inhibitors such as furfural, acetate, and phenolics in xylose mother liquor. The present study focused on fermenting xylose hydrolysate from sugarcane bagasse to produce xylitol using C. tropicalis strain31949. The effects of inoculum age, inoculum quantity, and initial xylose concentration on xylitol fermentation by C. tropicalis 31949 were discussed. The following optimum fermentation conditions were determined: inoculum quantity, 10%; inoculum age, 26h; and initial xylose concentration, 100g/L. Under these optimal fermentation conditions, C. tropicalis 31949 could ferment sugarcane bagasse hydrolysate, which was pretreated by vacuum concentration and activated carbon detoxification decoloration, to produce 62.9800g/L xylitol.

用超声辅助双碱(NaOH/氨水)的方法预处理酶解蔗渣,利用热带假丝酵母发酵蔗渣水解液生产木糖醇,优化发酵的工艺参数.以木糖醇质量浓度为参照指标,分别考察了种龄、接种量、木糖初始质量浓度对热带假丝发酵蔗渣水解液生产木糖醇的影响,得出种龄为26 h,接种量为10％,木糖初始质量浓度为100 g/L为发酵木糖醇最适条件.在最适条件下,热带假丝酵母菌以蔗渣酶解液为原料发酵54 h,最终木糖醇质量浓度达到62.98 g/L.结果证明,热带假丝酵母菌可以有效发酵蔗渣水解液,有一定的研究意义.

Ultrasonic-assisted NaOH,KOH,Ca(OH)2 and ammonium hydroxide are used to digest bagasse.The concentration of xylose in the hydrolyzate is used as a reference index to compare the effects of different pretreatments.The experimental results show that ultrasonic assisted NaOH/ammonium hydroxide has the best effect,xylose concentration is 1.928 g/L.

In order to solve the problem that essential oil is easy to be volatilized and oxidized,many methods have been developed to microencapsulate the essential oil,including physical and mechanical method,physicochemical method and chemical method.The complex coacervation in physicochemical method is the most commonly used and the most gentle method for producing the essential oil microcapsules. The essential oil microcapsules prepared by the complex coacervation method have a good protective effect on the core material and can achieve the effects of controlled release and sustained release with better heat resistance and moisture resistance,so that it can be stored in high-temperature and high-humidity environment with little deterioration.In this paper,the development history of complex coacervation, the selection of wall materials and the examples of essential oil microcapsules prepared in recent years are reviewed,laying a foundation for the future development of essential oil microcapsules.

Applications for l-lactic acid are increasing. Recent studies have investigated inexpensive raw materials for producing l-lactic acid and have explored technical principles. We optimized fermentation conditions for enzymatic hydrolysis of sugarcane bagasse as a substrate for l-lactic acid production, and to achieve a high conversion rate of bagasse to l-lactic acid using Rhizopus oryzae. The maximum conversion rate of l-lactic acid was 28.45% in the conditions of 48-h fermentation time and 200 r/min rotary shaking in 50 mL liquid medium with 10% inoculum. The kinetics of fermentation were worked out. Logistic equations, Luedeking–Piret equations and Luedeking–Piret-like equations were chosen as kinetic models. Three kinetic models were constructed which reflected microbial growth, product synthesis and substrate consumption; R2 of three kinetics model equations, respectively, were 0.9799, 0.9869, 0.9911, which indicated that the predicted values fit the experimental data and the equations accurately describe the fermentation process of R. oryzae Gim3.129 for producing l-lactic acid. The models described the fermentation process of R. oryzae Gim3.129 successfully and provided a theoretical foundation for the industrialization of l-lactic acid from sugarcane bagasse.

Xylo-oligosaccharide is a kind of functional oligosaccharide.It plays an important role in the aspects of food, health care products, medicines agriculture and so on.Expound the structure properties,functional features and preparation methods of xylo-oligosaccharide, and also summarize the research progress and application at home and abroad.The research and development of high-value application of xylo-oligosaccharide will bring great economic and social benefits.

以甘蔗糖蜜为原料,采用聚氨酯泡沫固定米曲霉进行发酵试验,探究聚氯酯泡沫固定化米曲霉的条件,及固定化米曲霉发酵糖蜜的最优条件.试验得出,固定化最优条件为:聚氨酯泡沫载体最佳尺寸为2 mm×2 mm×2 mm,最佳填充量为1.0 g/60 mL发酵液,曲酸最高浓度可达15.43 g/L,用此固定化酶发酵酸处理的糖蜜,当糖蜜培养基中耱浓度80g/L时,获得的曲酸最高浓度为9.02 g/L.