摘要
通过GC-MS测定新陈大米中脂肪酸的含量发现:大米陈化后多不饱和脂肪酸质量分数由64.5%降至43.18%,饱和脂肪酸质量分数由21.48%升至27.63%,亚油酸和油酸含量之比由0.26升至0.61,大米品质变差;电子鼻检测新陈大米的气味发现差异显著。GC-MS检测陈米挥发性成分发现:脂肪酸氧化生成醛酮类物质,醛类由45.76%升至62.31%,产生十九烷、癸烷等刺激性气体,使大米散发不愉悦的"陈米味"。红外光谱分析发现:脂肪酸特征吸收峰1745、1149、1017 cm^(-1)明显降低,CH=CH在930 cm^(-1)处的特征吸收峰减弱,不饱和脂肪酸降解,在1 709cm^(-1)处出现羰基化合物的特征峰表明生成醛酮类物质,印证了GC-MS所得结论;DSC分析发现大米陈化后蛋白质强度增大,淀粉结晶解体,致使大米糊化起始温度由58.7℃升至61.4℃,终点温度由63.1℃升至64.4℃。
The fatty acid contents were measured by GC - MS. It was found that the content of polyunsaturated fatty acid decreased from 64.5% to 43. 18% , and the content of saturated fatty acid increased from 21.48% to 27.63 %. The ratio of linoleic and oleic increased from 2.6 litres to 6.1 litres, which turned out the poor quality of aged rice. It showed significant difference of aged and fresh rice by electronic nose. It was found after volatile compo- nents tests by GC -MS： The oxidation of fatty acid generated aldehydes and ketones. Aldehydes increased from 45.76% to 62.31% , and nonadecane, deeane and other irritant gases arose made rice emit unpleasant ＂smell of old rice＂. It could be confirmed by Infrared spectrum analysis that the characteristic absorption peaks of fatty acid such as 1 745 cm-1 ,11 49 cm-1 ,1 017 cm-1 significantly declined. The characteristic absorption peak of 930 cm-l referred to CH = CH receded. Some of unsaturated fatty acid oxidation degraded, the appearance of 1 709 cm - ~ peak of carbon- yl compound characteristic showed that aldehydes and ketones were generated which verified GC - MS conclusion. The DSC results showed that intensity of aged rice protein enhanced and the crystallization of starch were degraded, which led to the initial temperature of rice gelatinizing increased from 58.7 ℃to 61.4 ℃ and end temperature rose from 63.1 ℃ to 64.4℃.
出处
《中国粮油学报》
EI
CAS
CSCD
北大核心
2016年第8期1-5,29,共6页
Journal of the Chinese Cereals and Oils Association
基金
浙江省重大科技专项重点社会发展项目(2009C03017-1)
宁波市重点学科资助项目(szx11070)
关键词
新陈大米
脂肪酸
氨基酸
GC-MS
红外光谱
aged and fresh rice, fatty acids, amino acid, GC - MS, infrared spectroscopy
