Development of ready-to-eat Kanom Jeen

Kanom Jeen is a popular rice noodle product however, its storage shelf-life is short at room temperature. Thus, the objective of this study was to develop a process to extend its shelf –life with the acceptable quality. Firstly, the effect of acid (citric acid or lactic acid) during soaking on the physicochemical properties of rice flour was investigated. It was found that amylose, protein, and fat contents and viscosity of rice flour decreased while swelling power and solubility at 75℃ increased after acid treatment. Kanom Jeen prepared from acid - treated rice flour had higher tensile strength and springiness but lower hardness and stickiness than those of control sample. Kanom Jeen prepared from rice flour treated with 2% (w/w) citric acid had the highest whiteness index and overall liking score. Secondly, during steaming and kneading steps, the ratio of gelatinized to ungelatinized rice flour was varied at 15:85, 20:80 and 25:75. It was found that the gelatinized rice ratio at 15:85 gave the highest hardness Kanom Jeen. Next, the effect of adding citric acid (0.25%, w/w) and salt (7%, w/w) in the boiling water during cooking was studied and the results showed that the pH of Kanom Jeen was reduced to 3.88 without affecting the textural characteristics. After that, the sample was kept in PE/AL/PE – laminated pouch with nitrogen gas flushing and heated at 85℃ and 90℃ for 1, 3 and 5 min. The result showed that springiness and tensile strength of samples decreased whereas total aerobic plate count and yeast and moulds in sample were lower than 250 cfu/g and 100 cfu/g, respectively. The Kanom Jeen pasteurized at 90℃ for 3 min could be stored up to 29 days at room temperature.

卡诺金米粉（Kanom Jeen）是一款广受欢迎的米线类食品，但其室温货架期较短。因此，本研究旨在开发一种可延长其货架期且维持合格品质的工艺。首先，本研究考察了浸泡过程中酸（柠檬酸或乳酸）对米粉理化特性的影响。研究发现，经酸处理后，米粉的直链淀粉、蛋白质、脂肪含量及黏度均有所降低，而75℃下的膨胀力与溶解度则有所提升。以酸处理米粉制备的卡诺金米粉，其拉伸强度与弹性均高于对照组样品，而硬度与黏着性则更低；其中以2%（质量分数）柠檬酸处理的米粉制备的卡诺金米粉，其白度值与整体接受度评分均为最高。其次，在蒸制与揉合工序中，本研究设置了糊化米粉与未糊化米粉的比例分别为15:85、20:80及25:75的三组对照。结果表明，糊化米粉比例为15:85时，制备的卡诺金米粉硬度最高。随后，本研究考察了煮制过程中向沸水添加柠檬酸（0.25%，质量分数）与食盐（7%，质量分数）的效果，结果显示，卡诺金米粉的pH值可降至3.88，且未对其质构特性产生影响。之后，将样品置于聚乙烯/铝箔/聚乙烯（PE/AL/PE）复合包装袋中，充入氮气后分别于85℃与90℃下加热1、3及5分钟进行灭菌处理。结果显示，样品的弹性与拉伸强度有所降低，但样品的总需氧菌数与酵母菌、霉菌数分别低于250 cfu/g与100 cfu/g。经90℃灭菌3分钟的卡诺金米粉，可在室温下货架期延长至29天。