Nutritional quality analysis of different walnut varieties in Bazhong City, Sichuan Province

To clarify the nutritional quality differences between local walnut varieties and Juglans regia 'Qingxiang' in Bazhong City of Sichuan Province, the contents of protein, fat, ratio of linoleic acid to α-linolenic acid, vitamin B₂, vitamin E, and mineral elements such as iron, zinc, selenium, and strontium and other mineral elements were systematically determined. The results showed that there were differences in various nutritional indicators among different walnut varieties. The protein content ranged from 14.9 to 19.4 g/100 g, with walnut No.8 being the highest. The fat content ranged from 64.5% to 69.03%, with walnut No.2 being the highest. The ratio of linoleic acid to α-linolenic acid mostly fell within the range of 5~10, with walnut No.7 exhibiting a ratio of 5.43, which was in line with the recommended dietary nutrition guidelines. Variations were also observed in the contents of vitamin B₂ and vitamin E among the walnuts. The vitamin B₂ content in local Bazhong walnuts was generally higher than that in the Juglans regia 'Qingxiang'. With the exception of walnut No.2 and walnut No.4, which had lower vitamin E content compared with Juglans regia 'Qingxiang', the vitamin E content in the remaining local Bazhong walnuts was significantly higher. Mineral element analysis revealed that walnut No.6 from Bazhong had the highest iron and zinc contents. Selenium was only detected in some local Bazhong walnuts, with walnut No.4 being the highest. Additionally, the strontium content in most local Bazhong walnuts was significantly higher than that in the control group. Through a comprehensive evaluation of the key nutritional qualities of different walnuts from Bazhong City, Sichuan Province, this study provides a scientific basis for selecting high-quality walnut varieties suitable for the ecological conditions there, as well as for subsequent functional development of such walnut varieties.