改进谷类休闲食品质量的挤压熟化工艺

<正> 随着社会经济的不断进步,人们生活水平的逐步提高,对食品的要求也产生极大的变化。过往,进食的目的在于充饥,要求的食品只要能填饱肚子便已足够;时至今日,人们不但要求要食得健康,而且许多时候进食只为消遣。休闲食品就是在这样的条件下,成为备受欢迎的产物。 休闲食品的种类琳琅满目,其制造工艺也非常多样化。下文介绍的挤压熟化工艺,是生产即食谷类早餐和休闲食品的理想工艺。     

Extrusion cooking and bioconversions

The versatility of an HTST-extrusion cooker provides possibilities for its use as a continuous chemical and/or biochemical reactor. Biopolymer-containing materials may be thermomechanically modified for a variety of end uses or pretreated for subsequent biotechnical applications. Enzymes may be inactivated for improved product shelf-life and for utilization of sprouted cereal grain. On the other hand, thermostable α-amylase can be employed for partial starch hydrolysis during and after extrusion, and the extrusion-liquefied starches may be used for subsequent syrup manufacture, or ethanol and other fermentations.     

三种谷物的不同乙醇浓度提取物抗氧化活性研究

以高粱、紫米、大黄米为原料,以水、60%、95%乙醇为提取介质,对提取物的总酚含量、DPPH·清除能力和总抗氧化能力进行了测定。同时,分析了三种谷物60%提取物对小鼠红细胞溶血性的影响。结果表明:高粱水提物的总酚含量为2.34mg/g(GAE/DW),分别是紫米和大黄米的4倍和12.23倍;DPPH·清除率达到43.58%,而紫米和大黄米的水提物基本无清除DPPH自由基的能力。高粱、紫米、大黄米的60%乙醇提取物的DPPH·清除能力分别为89.88%、90.16%、64.70%,高粱的总抗氧化能力为0.16mmol/g(TEAC/DW),分别是紫米和大黄米的3.99倍和24.89倍。大黄米的95%乙醇提取物总酚含量较高,达到1.38mg/g(GAE/DW),具有较强的总抗氧化能力,但DPPH·清除能力较低。高粱、紫米、大黄米在2mg/mL时对H2O2诱导的红细胞氧化溶血的抑制率分别为50.77%、16.73%、22.79%。可见,高粱具有一定的保护红细胞膜的作用。     

纤维乙醇用酵母菌的驯化

酵母菌菌种性能的优劣直接关系纤维乙醇发酵质量的好坏及设备的利用率等,进而影响企业的经济效益.该文通过对纤维乙醇生产用酵母菌株的驯化,获得一株驯化酵母菌株:并将该菌株与1308菌株、1300菌株和安琪酵母发酵、耐乙酸、耐糠醛、耐羟甲基糠醛能力进行了对比试验,结果表明该驯化酵母菌株发酵能力、耐受性均优于其他供试菌株;更适宜于在纤维乙醇生产中应用.     

Alginate-loofa as carrier matrix for ethanol production

An alginate-loofa matrix was developed as a cell carrier for ethanol fermentation owing to its porous structure and strong fibrous nature. The matrix was effective for cell immobilization and had good mechanical strength and stability for long-term use. After a storage period of 4 months, yeast cells remained firmly immobilized and active.     

Microstructural changes of starch in cooked wheat grains as affected by cooking temperatures and times

The changes of starch microstructure in soft and hard wheat grains after cooking in a pressure cooker were investigated using a scanning electron microscope (SEM) and a light microscope (LM) in conjunction with image analysis. The conditions studied included variation of the cooking times (20-120 min) at the constant temperature (120 °C) and with variable temperatures (110-140 °C) for constant time (40 min). SEM images showed that steam induced changes in the intact starch granules of cooked wheat grains, with the microstructure becoming more in mud-like structure, with increased cooking time or temperature. The swelling and gelatinization of starch granules could contribute to this change. Suspensions of cooked wheat flour were selectively stained with iodine, for observation using the LM. The image analysis software was used for quantitative analysis of the images captured from the LM, providing both the number and area of the starch granules (determined from the dark-blue spots) per fixed image size. With increased cooking time or temperature, the number of starch granules decreased and the area increased as a result from the swelling and melting of starch granules. This study demonstrated the use of SEM and LM for the investigation of starch granules in cooked wheat grains without prior starch isolation.     

亚麻制浆蒸煮漂白的生产与工艺

亚麻纤维具有纤维长、强度高、纤维素含量高、燃烧无异味等优点,是生产高档卷烟纸的优质原料。传统的单段次氯酸盐漂白和CEH三段漂白,很难使亚麻浆白度达到高档卷烟纸的要求。采用CEHP四段漂白工艺,使亚麻浆白度达到85%ISO,满足生产高档卷烟纸需求。     

Polysaccharide production by kefir grains during whey fermentation

Fermentation of deproteinised whey with kefir grains CIDCA AGK1 was studied focusing on polysaccharide production from lactose. Kefir grains were able to acidify whey at different rates depending on the grain/whey ratio. During fermentation, kefir grains increased their weight and a water-soluble polysaccharide was released to the media. Exopolysaccharide concentration increased with fermentation time, reaching values of 57.2 and 103.4 mg/l after 5 days of fermentation in cultures with 10 and 100 g kefir grains/l, respectively. The polysaccharide fraction quantified after fermentation corresponded to the soluble fraction, because part of the polysaccharide became a component of the grain. Weight of kefir grains varied depending on the time of fermentation. Polysaccharide production was affected by temperature. Although the highest concentration of polysaccharide in the media was observed at 43 degrees C at both grain/whey ratios, the weight of the grains decreased in these conditions. In conclusion, kefir grains were able to acidify deproteinised whey, reducing lactose concentration, increasing their weight and producing a soluble polysaccharide.     

挤压蒸煮技术在变性淀粉生产中的应用

主要阐述了挤压加工原理,以及用挤压机作反应器生产氧化、酯化、交联和醚化等多种类型的变性淀粉,并对其相关性质进行了简要分析。认为挤压蒸煮技术是快速、连续生产多种变性淀粉的一种经济可行的方法。     

木质纤维素生产乙醇的大型试验

乙醇是以木质纤维素为原料,通过蒸气预处理、纤维素酶的牛产、酶水解、酒精发酵等工艺而制成的.该文主要阐述用木质纤维素生产乙醇的方法和工艺流程.     

二氧化氯对玉米乙醇发酵糟液中脱氧雪腐镰刀菌烯醇的降解

脱氧雪腐镰刀菌烯醇(deoxynivalenol,DON)是造成粮食污染的主要原因之一。采用高效液相色谱-质谱联用(HPLC-MS)对DON含量进行检测分析,通过液体浸泡法,探究了ClO_2对DON纯品以及玉米乙醇发酵糟液中DON的降解效果。结果显示:DON降解率随ClO_2溶液浓度的增大以及处理时间的延长而提高,且pH值对DON降解有影响。当pH值为4. 5～5. 5时,600 mg/L ClO_2溶液对DON纯品处理12 h,降解率为28. 23%,并产生了2种降解产物;该方法同样适用于玉米乙醇发酵糟液中DON降解,600 mg/L的ClO_2溶液对玉米发酵糟液处理12 h,降解率达40. 70%,降解效果较好,对处理乙醇发酵工艺中的DON或其他真菌毒素具有一定的指导意义,为大规模生产中对DON的去除提供了新的思路。     

非木材纤维制浆清洁生产技术方案备料与蒸煮工段

我国人多地少,森林资源相对匮乏,林纸一体化不能完全解决原料短缺问题,而同时我国非木材纤维原料很丰富,加强非木材纤维原料制浆造纸意义重大。以苇浆生产线备料和蒸煮工段为例,采用先进和清洁生产的工艺技术和设备,可以最大限度地实现物质和能量的综合循环使用,符合制浆造纸行业清洁生产评价指标体系和循环经济的要求。本文重点介绍了芦苇原料备料和蒸煮工段的清洁生产技术方案。     

强化发酵丢糟再生产白酒的研究

通过加入强化发酵菌株、糖化酶、大曲粉、复合酶对白酒丢糟进行强化发酵生产复糟酒,研究结果表明,强化发酵菌株、糖化酶、大曲、复合酶的加入量为6.0‰、60U/g、6‰、5‰,发酵时间为35d时产酒最多且酒质最好.     

蒸球进汽系统的改造和蔗渣蒸煮工艺

随着甘蔗渣制浆原料的不断变化并为满足生产和蒸煮工艺的需求,蒸球设备在经过单一、三条和四条蒸汽管进行蒸煮的不断改进过程中,采用了目前较为先进的自动控制进汽系统和32段蒸煮工艺曲线进行生产,使蒸煮质量稳定、原浆生产成本低,达到挖掘潜能和节能减排的目的。     

Continuous production of pectinase by immobilized yeast cells on spent grains

A yeast strain secreting endopolygalacturonase was used in this work to study the possibility of continuous production of this enzyme. It is a feasible and interesting alternative to fungal batch production essentially due to the specificity of the type of pectinase excreted by Kluyveromyces marxianus CCT 3172, to the lower broth viscosity and to the easier downstream operations. In order to increase the reactors' productivity, a cellulosic carrier obtained from barley spent grains was tested as an immobilization support. Two types of reactors were studied for pectinase production using glucose as a carbon and energy source--a continuous stirred tank reactor (CSTR) and a packed bed reactor (PBR) with recycled flow. The highest value for pectinase volumetric productivity (P(V)=0.98 U ml(-1) h(-1)) was achieved in the PBR for D=0.40 h(-1), a glucose concentration on the inlet of S(in)=20 g l(-1), and a biomass load in the support of X(i)=0.225 g g(-1). The results demonstrate the attractiveness of the packed bed system for pectinase production.     

以白酒酒糟为原料发酵产丁二酸

以白酒酒糟为原料,经酶法糖化,由Actinobacillus succinogenes发酵生产丁二酸。纤维素酶或糖化酶分别水解白酒糟,在酶反应的最适温度和pH条件下,酒糟中的纤维素和淀粉的水解率分别为44.04%和92.26%,相应还原糖对酒糟的得率分别为110 mg/g和126 mg/g酒糟;但2种酶以分步或同步方式水解白酒糟时,酶水解反应受到产物抑制作用,总还原糖得率仅约为150 mg/g酒糟。采用分步糖化发酵工艺,400 g/L白酒糟经两种酶水解后,得到还原糖58.4 g/L,该水解液发酵产丁二酸28.8 g/L,丁二酸产率72 mg/g酒糟;而采用先用纤维素酶水解白酒糟,再用糖化酶和A.succinogenes同步糖化发酵的工艺,240 g/L白酒糟产丁二酸浓度为32 g/L,产率133 mg/g酒糟。以白酒酒糟为原料发酵生产丁二酸,利用了废弃物,无需外源添加氮源,无需对原料进行酸碱预处理,具有一定的应用前景。     

Quantifying cyanogenic glycoside production in the acrospires of germinating barley grains

Ethyl carbamate is an undesirable trace component in distilled beverages and its content in Scotch whisky is largely determined by the cyanogenic pre‐cursor, epi‐heterodendrin (EPH) from malted barley. A rapid colorimetric procedure can identify cultivars that do not produce EPH and attempts were made to quantify this test, to determine differing levels of production. Using a given fresh weight of acrospire tissue from germinated grain, it was possible to distinguish between genotypes but differences between replicates were substantial. Acrospire length was not a reliable indicator of EPH production and genotypes differed not only in the quantity of EPH produced but in the rate and pattern of production. © 1999 Society of Chemical Industry     

Milk production response to diets supplemented with dried brewers grains, wet brewers grains, or soybean meal

Forty four multiparous Holsteins, 114 +/- 28 days in milk (32 kg/day, 3.4% fat), were fed a basal diet of 12% crude protein and 20% acid detergent fiber for 10 days, then stratified by milk production into four groups. Cows were randomized to one of nine diets in a 3 X 3 factorial in which basal was supplemented with dried brewers grains, wet brewers grains, or soybean meal to supply in the diet 14.5, 16.0, and 17.5% crude protein. Eight cows remained on basal during the 50-day trial. Basal contained: 14% alfalfa silage, 27% ensiled ground-corn, 53% corn silage, and 6% vitamin-mineral mix. Milk production (kg/day) for cows fed dried brewers grains (29.4) and wet brewers grains (28.9) was higher than soybean meal (26.2) and basal (23.1). Milk production was different for diets with high (29.6) vs. low (27.8) and medium (27.2) protein. Dry matter intake (as percent of body weight) was 3.7, 3.5, 3.3, and 2.9 for dried brewers, wet brewers, soybean meal, and basal, respectively. Milk protein percent and milk fat percent differed for protein source. Rumen fluid ammonia nitrogen for combined 2, 4, and 6 h post-feeding, was (mg/100 ml) 10.4 for dried brewers, 14.9 for wet brewers, and 18.0 for soybean meal and increased from 13.2 to 15.4 with increased protein. Plasma urea tended to follow patterns of rumen ammonia. Dried brewers grains had lower apparent nitrogen digestibility but equal nitrogen balance, indicating more efficient metabolic use than soybean meal.