การประยุกต์เทคโนโลยีการลดอุณหภูมิในการผลิตบรอกโคลีเพื่อรักษาคุณภาพตลอดสายโซ่อุปทาน

Abstract

The broccoli respiration after harvest is high leads to rapidly senescence primary expressed as yellowing of the florets. Therefore, postharvest handling, especially rapid cooling is an important factor affecting the shelf life of broccoli. The yellowing of floret of broccoli is a limiting factor in the shelf-life of broccoli florets and commonly associated with nutritional and commercial value of broccoli during storage. Moreover, broccoli grown in highland, Chiang Mai, Thailand, which is tropical country resulted in average of five days shelf life at 8 : 1 C. The color change of the florets from green to yellow directly affects consumer acceptance. Precooling and temperature management are widely used to prolong shelf life of fruits and vegetables. The goal of this study aimed at investigating effect of ice and vacuum cooling on qualities and shelf life of broccoli throughout the supply chain. Copyright@ by Chiang Mai University Three experiments were conducted in this study. In the experiment 1, first the optimum condition using ice cooling (1:1, 2:1 and 3:1 in the ratio of ice to weight of broccoli) and vacuum cooling method (6 and 6.5 mbar holding pressure with 10, 15, 20, 25 and 30 minutes holding time) were investigated. The optimum condition of ice cooling in which the ratio of ice to broccoli was 1:1. Optimum condition for vacuum cooling of broccoli was 0.6 kPa holding pressure with 30 min holding time. The study illustrated that both precooling techniques could reduce broccoli core temperature from initial temperature of 21-23 C to the final temperature of 4 + 1C. Weight loss of broccoli precooled by ice cooling and vacuum cooling accounted to 1.08 % and 1.69 % which were significanlly (P0.05) lower than 2.13 % of control sample. For second experiment, the effect of ice cooling and vacuum cooling on physico-chemical qualities and microorganism of broccoli after precooled were examined. After 5 day, it was found that ice cooling and vacuum cooling reduced weight loss percentage compared with control treatment. Likewise, slow down the decomposition of color values consist of lightness, hue angle and chroma value. Notably, the higher contents of vitamin c, total chlorophylls content and antioxidant activity as well as total phenolics content in vacuum and ice cooling pretreated samples could be attributed to precooling. This resulted cause to resist of microorganisms during storage and ultimately leads to a longer shelf life. The third experiment explored the effect of ice cooling and vacuum cooling on physico-chemical qualities, microorganism, sensory quality and shelf life of broccoli throughout the supply chain. Results indicated that precooling treatment of broccoli maintained the quality in terms of physico-chemical, showed the high vitamin c content, total chlorophylls content and antioxidant activity along with total phenolics content. Also, inhibited yellowing of florets that bring about to high sensory evaluation scores covering microbiological and enhanced the shelf-life. The ice cooling was the most effective method for extending the shelf life of postharvest broccoli form 5 to 12 days at 8+ 1 ㆍC and 85% RH, improving the produce market window.