基于多元化学计量法的核桃仁炮制前后品质评价

Comprehensive evaluation on quality of walnut kernel before and after processing based on multivariate stoichiometry

中文关键词:  核桃仁  脂肪酸  主成分分析  聚类分析  品质综合评价

英文关键词:walnut kernel  fatty acid  principal component analysis  cluster analysis  quality comprehensive evaluation

中文摘要:

      目的 比较不同产地核桃仁炒制前后的品质差异。方法 收集我国7个核桃主产区的核桃样品, 进行外观性状评价, 并采用清炒法制备生、炒核桃仁。参照国家标准方法测定核桃仁的水分、灰分、粗脂肪和粗蛋白含量, 采用气相色谱-质谱法测定脂肪酸组成, 采用主成分分析和聚类分析等方法综合评价其品质差异性。结果 生品中水分含量为3.89%~5.09%、灰分含量为1.64%~2.16%、粗脂肪含量为64.15%~69.26%、粗蛋白含量为17.38%~18.97%; 炒制后水分含量为2.83%~3.68%、灰分含量为1.64%~2.11%、粗脂肪含量为68.32%~71.71%、粗蛋白含量为14.94%~18.87%。炒制后各产地核桃仁水分降低, 粗脂肪含量升高。核桃仁中的脂肪酸主要由棕榈酸、硬脂酸、油酸、亚油酸、α-亚麻酸组成, 生品中相对含量分别为5.23%~8.55%、1.80%~3.99%、14.30%~32.29%、52.95%~63.96%和6.80%~11.13%, 炒品中相对含量分别为6.00%~7.94%、未检出~2.38%、17.59%~31.85%、49.89%~63.49%和8.18%~13.35%, 炒制后不饱和脂肪酸含量由88.39%~92.21%升高为89.85%~97.72%。主成分分析显示山西生核桃仁的综合得分最高; 聚类分析结果显示陕西、山西、河北核桃仁相似度较高。结论 核桃仁经炒制后能够降低水分, 增加粗脂肪及不饱和脂肪酸含量。不同产地核桃仁的品质差异较大, 陕西、山西和河北3个产地的核桃仁品质优于其他产地。

英文摘要:

      Objective To compare the quality differences of walnut kernels from different places before and after frying. Methods Walnut samples from 7 major walnut producing areas in China were collected for appearance traits evaluation and the raw and fried walnuts were prepared by stir-frying method. The moisture, ash, crude fat and crude protein content of walnut kernel were determined according to the national standard method, the fatty acid composition was determined by gas chromatography-mass spectrometry, and the quality differences were comprehensively evaluated by principal component analysis and clustering analysis. Results The water content in the raw product was 3.89%?5.09%, ash content was 1.64%?2.16%, crude fat content was 64.15%?69.26% and crude protein content was 17.38%?18.97%; after frying, the water content was 2.83%?3.68%, the ash content was 1.64%?2.11%, the crude fat content was 68.32%?71.71% and the crude protein content was 14.94%?18.87%. After frying, the water content of walnut meat from different origins decreased and the crude fat content increased. The fatty acid in the walnut kernel mainly consists of palmitic acid, stearic acid, oleic acid, linoleic acid and α-linolenic acid, and the relative content in the raw products were 5.23?8.55%, 1.80?3.99%, 14.30?32.29%, 52.95?63.96% and 6.80?11.13% respectively, the relative content in that stir-fry product was 6.00%?7.94%, not detected?2.38%, 17.59%?31.85%, 49.89%?63.49% and 8.18%?13.35% respectively, and the content of the unsaturated fatty acid increase from 88.39%?92.21% to 89.85%?97.72% after stir-frying. Principal component analysis showed that Shanxi raw walnut kernel had the highest comprehensive score; the results of clustering analysis showed that the similarity of walnut kernel from Shaanxi, Shanxi and Hebei was high. Conclusion After frying walnut kernel, it can reduce moisture and increase the content of crude fat and unsaturated fatty acids. The quality of walnut kernels from different producing areas is quite different, the quality of walnut kernels from Shaanxi, Shanxi and Hebei Provinces is better than that from other producing areas.