加工处理方法对大米性质和微结构影响的研究

发布时间：2018-01-03 21:00

  本文关键词：加工处理方法对大米性质和微结构影响的研究　出处：《安徽工程大学》2017年硕士论文　论文类型：学位论文

  更多相关文章： 工艺优化 性质变化 微结构变化

【摘要】：方便米饭是由工业大规模生产的,在食用前只需简单烹调或直接食用,与普通米饭口感风味一致的主食食品。方便米饭的制作需经过浸泡、蒸煮、干燥和杀菌等工艺,这些加工方法引起大米微生物菌落变化,改变了大米微结构,造成回生率上升,溶胀能力改变及复水性差等问题。本课题研究了浸泡工艺下大米微生物菌落变化,建立了大米浸泡、微波加热和蒸煮三种工艺的最佳参数,并利用SEM、XRD、FT-IR、DTA、TGA等方法,表征加工处理前后微结构变化,来探究大米回生特性,溶胀能力及复水特性的改变。得到以下结果:(1)在方便米饭加工方法中,浸泡工艺可以较好的保持米饭风味,然而大米含水量的上升也会引起微生物菌落的大量生长和回生率的上升。通过研究发现,随着浸泡时间的延长,菌落总数快速上升,在浸泡7天后菌落总数超标,霉菌和酵母的生长速度明显小于细菌的生长速度。大米的含水量随浸泡时间与温度上升而增大,大米回生率与含水量呈正相关,方便米饭实际生产应用中,浸泡条件为60 min,25℃为最佳工艺参数。为研究回生率的上升原因,对大米微结构进行表征,发现大米淀粉微结构出现凹陷和粘连现象,晶体结构依然是A型,然而随着水进入大米内部结构,大米的氢键数量减少,相对结晶度下降后趋于稳定,淀粉分子趋向于有序化,加大淀粉回生。(2)在方便米饭加工方法中,微波加热工艺有快速膨化和杀菌的作用,然而过度的微波热效应会引起大米溶胀能力改变,影响人体对营养物质的吸收。通过研究发现,大米的溶胀能力随含水量上升而上升,随微波功率增加溶胀能力先上升后下降。方便米饭实际生产应用中,浸泡60 min,在464 W下微波加热10 min为最佳的大米微波处理工艺参数。为研究溶胀能力变化原因,对微波处理前后的大米进行表征,发现大米淀粉微结构出现凹陷现象,晶体结构属于A型,在微波热效应下,淀粉内部结构发生断裂,还原性羟基与水结合能力上升,大米的氢键数量减少,相对结晶度较处理前下降并趋于稳定,淀粉分子稳定性上升,溶胀能力加强。(3)在方便米饭加工方法中,蒸煮工艺可以保存大米营养又提高风味,然而蒸煮条件的改变也会引起营养流失,感官品质下降等问题。通过研究发现,大米的复水特性随米水比和蒸煮时间呈波浪形变化,方便米饭工艺中,米水比1:7蒸煮7.0 min为较好保持大米复水特性工艺参数。为研究复水特性变化原因,对大米微结构进行表征,发现大米表面和剖面微结构出现海绵状结构,在蒸煮工艺下,温度的上升使淀粉脂类复合物逐渐形成,结晶区域被破坏,相对结晶度下降,水进入淀粉内部,引起淀粉分子间的氢键断裂,温度与水双方面作用使复水特性发生波浪式变化。
[Abstract]:Instant rice is produced in a large scale by industry. It only needs simple cooking or direct consumption before eating. It is a staple food with the same taste as common rice. The preparation of instant rice needs to be soaked and cooked. Drying and sterilization technology, these processing methods caused changes in the microbial colony of rice, changed the rice microstructure, resulting in an increase in the rate of regrowth. The change of microbial colony of rice under soaking process was studied. The optimum parameters of rice soaking, microwave heating and cooking were established, and SEM was used. Methods such as XRDX FT-IRT-DTA-TGA were used to characterize the microstructure changes before and after processing in order to explore the characteristics of rice retrogradation. The change of swelling ability and rehydration characteristics. The following results were obtained: 1) in the processing method of instant rice, the steeping process could better maintain the flavor of rice. However, the increase of rice water content will also cause a large number of microbial colonies to grow and the rate of regrowth. Through the study, it is found that with the extension of soaking time, the total number of colonies increases rapidly. After soaking for 7 days, the total number of colonies exceeded the standard, and the growth rate of fungi and yeast was obviously lower than that of bacteria. The water content of rice increased with the soaking time and temperature, and the rate of rice regrowth was positively correlated with the water content. In the practical application of instant rice, the optimum technological parameter was 60 min ~ 25 鈩，

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