乾燥方法與稻穀成熟度對稻米胴裂率及食味品質之影響

Effects of Drying and Maturity Conditions and Moisture Content on Grain Cracking Ratio and Eating Quality of Rice

何榮祥(H. S. Ho) ； 宋勳(H. Song) ； 許愛娜(A. N. Hsu) ； 林國照(K. C. Lin)

《臺中區農業改良場研究彙報》 30期 (1991/03) Pp. 1-13

https://doi.org/10.6956/BTDAIS.199103.0001

摘要

本試驗主要目的在探討不同乾燥方法、乾燥程度及不同成熟度之稻谷在乾燥過程中所造成之胴裂及食味品質之影響，以及乾燥後稻穀在儲存期間，稻穀隨溫度、濕度之變化，造成吸濕與去濕之現象，對稻米胴裂之影響，根據調查結果：不同乾燥處理與不同乾燥程度的稻穀含水率對稻米胴裂率均有顯著差異影響存在，而二者又以不同乾燥處理對稻米胴裂影響為大。不同乾燥處理下稻米胴裂率有隨乾燥溫度增加而增加的現象，但乾燥初期採用較高溫度乾燥，待稻穀含水率下降至20%以後予以適當降低乾燥溫度，此種先高後低之變溫乾燥方式，有助於降低胴裂率，並兼顧乾燥機之作業效率。乾燥後稻穀胴裂率隨含水率之下降其胴裂率亦隨之增加，當水份含量過低於14%後胴裂率隨之快速增加。不同乾燥處理與不同的乾燥程度對稻米食味品質之影響不明顯。稻穀在田間隨著成熟度之增加，稻穀含水率隨之下降其胴裂率亦隨之增加，乾燥後亦同，其中超過收穫適期之晚收處理乾燥後，稻米胴裂有急速惡化之現象。在貯存過程中，各處理之胴裂率均有逐日增加之現象，其中以乾燥至12%之稻穀胴裂增加最顯著，而含水率為15%與14%之稻穀其胴裂變化較小，故稻穀實不宜過度乾燥，以免於儲存期間，因吸濕作用而造成大量胴裂。米飯食味方面，二期作之生產條件下，提早收穫之米飯食味較差，但一期作之生產條件下，不同收穫期間之食味並無顯著差異。

關鍵字

水稻 ； 米質 ； 成熟度 ； 乾燥 ； 胴裂

並列摘要

This experiment is to study the effects of maturity, drying conditions and moisture contents on the ratio of grain cracking and eating quality of rice. There were significant differences of both drying conditions and the rice moisture content on the effects of cracking ratio of rice grain. The drying conditions is more important than the rice moisture content on crack ratio. The cracking ratio increase with the increase of drying temperature. The best procedure is using high temperature to reduce the moisture content of rice to 20%, then decrease the drying temperature. This method will reduce the cracking ratio and increase dryer operation efficiency. Drying conditions and moisture content had little effects on the eating quality of cooked rice. Brown rice cracking ratio will increase with maturity stages in the field. There were no significant difference on cracking ratio and eating quality between 2 steps (45-40℃) and 3 steps (50-45-42℃) drying process under the same maturity conditions. Moisture absorption resulted to fissuring of the grain, and increasing the crack ratio. The over-dried grain (12% w. b.) are more seriously than suitable dried grain (14, 15% w. b.) on crack ratio when storaged under the same circumstance due to moisture absorption.

並列關鍵字

rice ； rice quality ； maturity condition ； drying ； cracking