超高压处理对变温结晶制备糯米慢消化淀粉的影响

以糯米粉(蛋白质量分数为7.97％)和糯米淀粉(蛋白质量分数为0.58％)为研究对象,利用超高压(100、300、500 MPa)结合变温结晶(4℃和25℃间隔24 h循环条件下放置1、3、7 d)的方式制备慢消化淀粉,通过测定样品的慢消化淀粉质量分数并进行热力学性质、糊化特性和傅里叶变换红外光谱分析,研究超高压处理对...     

Effects of rice bran fermented with Lactobacillus plantarum on palatability,volatile profiles,and antioxidant activity of brown rice noodles

Brown rice noodles (RN) are typical whole-grain products with health benefits. This study investigated the effects of rice bran fermented with Lactobacillus plantarum on palatability, volatile profiles, and antioxidant activity of brown RN. Three kinds of RN, including RN, brown RN (BRN), and bran fermented RN (BFRN), were involved in this study. The results indicated that bran fermentation reduced the cooking loss of BFRN and improved the elongation and the sensory attributes of brown RN. After fermentation, aldehydes were significantly decreased while alcohols increased, and more pleasant flavours were shown in BFRN. Fermentation increased the content of free phenolics and decreased the content of bound phenolics. Among the four major phenolics detected in this study, ferulic acid was the most abundant one in all three RN samples. The DPPH radical scavenging activity and the ferric reducing antioxidant power of free phenolics in BFRN increased significantly compared to BRN. This study proved that rice bran fermentation is an effective approach to improve palatability, enrich the flavour as well as enhance the antioxidant activity of brown RN, which may facilitate the development of processing technology for brown RN.     

细菌纤维素膜对木醋杆菌发酵生产广式米醋的影响

以分离自广式米醋生产车间的木醋杆菌RF4(Gluconacetobacter xylinus)为菌种进行表面发酵。研究了发酵过程中细菌纤维素膜对总酸度的影响,纤维素膜内与发酵液中乙醇脱氢酶活性差异,讨论了3种不同接种培养方式对总酸度、黏度及浑浊度的影响。结果表明,纤维素膜完整性对发酵总酸度有重要影响,纤维素膜内乙醇脱氢酶活性是发酵液中的8倍,达2.26×10-2U/g。含木醋杆菌纤维素膜接种并中途取出的接种培养方式总酸度最高,发酵12天后可达4.86 g/100 mL,且黏度及浑浊度都较低。     

不同包装方法下大米储藏品质的变化研究

我国是大米的主要生产和消费大国,但由于经过加工后的大米失去了皮壳的保护层,在储藏期间常因呼吸、氧化和酶的作用而发生若干化学变化,从而导致其品质发生变化。因此,寻求一种利用现代科学技术加强保鲜效果,以延长大米保质期的包装方法迫在眉睫。研究了在自然、充CO2、充N2和抽真空包装方法下大米储藏品质的变化,结果表明,在4种包装方式中,真空包装的品质变化幅度最小,是延缓大米品质变化最好的一种包装方式。     

浸泡和超高压预处理对大米品质的影响

对浸泡和高压处理条件对大米品质的影响做了初步研究。实验表明,用0.8%的柠檬酸溶液浸泡大米有助于提高其糊化度,随着压强的升高,大米淀粉的糊化度逐渐增强,400 MPa压强下糊化度的边缘效应,能够显著降低大米的老化度,提高米饭的品质。     

Rice hull smoke extract inactivates Salmonella Typhimurium in laboratory media and protects infected mice against mortality

A previously characterized rice hull smoke extract (RHSE) was tested for bactericidal activity against Salmonella Typhimurium using the disc-diffusion method. The minimum inhibitory concentration (MIC) value of RHSE was 0.822% (v/v). The in vivo antibacterial activity of RHSE (1.0%, v/v) was also examined in a Salmonella-infected Balb/c mouse model. Mice infected with a sublethal dose of the pathogens were administered intraperitoneally a 1.0% solution of RHSE at four 12-h intervals during the 48-h experimental period. The results showed that RHSE inhibited bacterial growth by 59.4%, 51.4%, 39.6%, and 28.3% compared to 78.7%, 64.6%, 59.2%, and 43.2% inhibition with the medicinal antibiotic vancomycin (20 mg/mL). By contrast, 4 consecutive administrations at 12-h intervals elicited the most effective antibacterial effect of 75.0% and 85.5% growth reduction of the bacteria by RHSE and vancomycin, respectively. The combination of RHSE and vancomycin acted synergistically against the pathogen. The inclusion of RHSE (1.0% v/w) as part of a standard mouse diet fed for 2 wk decreased mortality of 10 mice infected with lethal doses of the Salmonella. Photomicrographs of histological changes in liver tissues show that RHSE also protected the liver against Salmonella-induced pathological necrosis lesions. These beneficial results suggest that the RHSE has the potential to complement wood-derived smokes as antimicrobial flavor formulations for application to human foods and animal feeds. PRACTICAL APPLICATION: The new antimicrobial and anti-inflammatory rice hull derived liquid smoke has the potential to complement widely used wood-derived liquid smokes as an antimicrobial flavor and health-promoting formulation for application to foods.     

新型方便米食用品质的研究

本文以大米粉作为主原料，复配食品添加剂，采用挤压技术生产“工程重组米”的新思路，完全克服传统工艺对大米进行表面处理的局限性，试图为制备具有良好品质的方便米另辟蹊径。本文研究了挤压工艺和传统工艺制备的方便米以及商用产品的食用品质。挤压工艺制备的方便米颜色浅白、不透明，糊化度高、表观密度较小、复水率稍高。传统工艺制备的方便米颜色较白、呈半透明，糊化度低、表观密度较大、复水率稍低。通过对复水后方便米饭的质构分析和感官评价发现，挤压工艺生产的方便米食用品质，除色泽外，均优于传统工艺制备的方便米食用品质，其品质接近杂交籼米新鲜米饭。     

多孔淀粉研究Ⅱ多孔淀粉形成工艺优化

本文主要研究以籼米为原料生产多孔淀粉的生产工艺。首先制备籼米淀粉，脱除蛋白质及纤维类物质；再确定酶解工艺条件，在单因子水平基础上进行RSA回归试验，分析得到最佳酶解参数；然后确定酶解下游工艺，即分离、提取及干燥等；最后是改善产品外观，主要是解决色泽问题。结果表明：讨论最佳酶解工艺参数是完全必要的。最佳工艺条件为酶组合（10：1），淀粉浆浓度（80％），加酶量（按水解淀粉40％的量，总酶活330IU／g生淀粉），pH3．6，温度（42℃），时间（22．5h），转速（100r／min）；其中冷冻干燥产品性能较好，产品色泽亦有了明显改善。本研究提供了一整套生产多孔淀粉的最佳工艺参数。     

多孔淀粉研究 II多孔淀粉形成工艺优化

本文主要研究以籼米为原料生产多孔淀粉的生产工艺。首先制备籼米淀粉,脱除蛋白质及纤维类物质;再确定酶解工艺条件,在单因子水平基础上进行RSA回归试验,分析得到最佳酶解参数;然后确定酶解下游工艺,即分离、提取及干燥等;最后是改善产品外观,主要是解决色泽问题。结果表明:讨论最佳酶解工艺参数是完全必要的。最佳工艺条件为酶组合(10:1),淀粉浆浓度(80%),加酶量(按水解淀粉40%的量,总酶活330IU/g生淀粉),pH3.6,温度(42℃),时间(22.5h),转速(100r/min);其中冷冻干燥产品性能较好,产品色泽亦有了明显改善。本研究提供了一整套生产多孔淀粉的最佳工艺参数。     

稻壳中纤维素、半纤维素和木质素的测定

阐述了几种不同的测定稻壳中纤维素、半纤维素和木质素含量的方法。最终选定测定稻壳中纤维素、半纤维素和木质素含量的方法分别为72％浓硫酸水解法、2mol／L盐酸水解法和浓硫酸法。结果测得纤维素、半纤维素、木质素含量分别为21．9％、19．0％、17．8％。