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Author Warunee Kupkanchanakul
Alternative Author Onanong Naivikul
เรื่องเต็มการประชุมทางวิชาการ ครั้งที่ 52 มหาวิทยาลัยเกษตรศาสตร์
TitleEffect of pre-germination process on molecular weight degradation and retrogradation of pre-germinated brown rice starches
Imprintการประชุมทางวิชาการ ครั้งที่ 52 เล่มที่ 6 สาขาอุตสาหกรรมเกษตร, 4-7 กุมภาพันธ์ 2557
Call# FOOD 8074

CALL # Volume Number Month Year Barcode Status

AbstractPaddy from two Thai rice cultivars as San-Pah-Tawng1 (SPT1, 5.25 percent db amylose) and Pathum-Thani1 (PTT1, 17.77 percent db amylose) were soaked at 30 deg C for 12 hours before pre-germinated in an incubator at 30 deg C, 85 percent relative humidity (RH) to get embryonic growth length at their first (0.5-1mm), second (1-2mm), third (2-3mm) and malted (3-7mm) stages. Then the chemical properties, starch molecular weight distribution and thermal properties, especially retrogradation, of pre-germinated brown rice starch (PGBRS) were determined by using brown rice starch (BRS) as a control. The total starch of brown rice from both rice cultivars (80.94-81.13 percent db) were significantly decreased (78.16-79.01 percent db) but the damaged starches were increased during the four stages of pre-germination. After pre-germination process, the amylose content of SPT1 was decreased to 4.75 percent db but that of PTT1 was increased to 18.73 percent db. When the average molecular weight and the molecular weight distribution of PGBRS molecules were revealed by using gel permeation chromatography (GPC), it was found that the rice starch molecule fractions, low molecular weight (MW) fraction (F2) (10**(2.5)-10**(6.5) g/mol) and high MW (F1) (10**(6.5)-10**(8.5) g/mol), were occurred on both rice cultivars. Increasing of low MW starch fractions after rice pre-germination process was observed from SPT1 (45.07 to 50.23 percent) and PTT1 (54.59 to 72.95 percent) which indicated that rice starch molecules were degraded as the embryonic growth length increased. The results from the differential scanning calorimeter (DSC) showed that the gelatinization temperatures of PGBRS from both rice cultivars had higher values than that of BRS. Then all gelatinized samples were kept at 4 deg C for 7days, the results showed that the delta enthalpy (delta Hret) of PGBRS from SPT1 was significantly decreased (pLT0.05) until the third stage (from 0.51 to 0.28J/g) but the malted stage was increased from the third stage to 0.40J/g, while that of PGBRS from PTT1 was significantly decreased (pLT0.05) from 1.24 to 0.72J/g. This result indicated that the starch molecules after pre-germination process were retrograded less than native starch molecules. Therefore, the pre-germination process could be applied to develop various rice products, such as rice bread.
Descriptหน้า 9-16
Subjectrice pre-germination process
pre-germinated brown rice starch
starch molecular weight