Abstract: The effects of blanching time on the nutritional quality and antioxidant activities of walnut male inflorescence (Juglans sigillata ‘Qianhe No. 7’) were investigated. The results indicated that blanching reduced obviously the contents of proximate components such as ash, fat and crude protein. The contents of soluble sugars, starch, titratable acid and ash dropped significantly after blanching for only 3 min. However, the fat content decreased remarkably at 6 min, and significant declines in the crude fiber and protein contents were observed at 9 and 12 min, respectively. The contents of mineral elements including potassium (K), iron (Fe), manganese (Mn) and zinc (Zn) lost seriously during blanching, followed by copper (Cu), phosphorus (P) and boron (B). However, the contents of magnesium (Mg) and calcium (Ca) were increased obviously during the whole blanching period of 15 min. Our results also showed that the essential amino acids lost more than non-essential amino acids and total amino acids during blanching and the loss rate of Phe and Val was the highest of all amino acids. Both total phenolics and total flavonoids were also significantly reduced with blanching time, which led to a reduction of antioxidant activities, but ferric reducing antioxidant power (FRAP) dropped more dramatically than 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity. Thus, the blanching time should be controlled within 3 min during the processing and cooking of walnut male inflorescences process in order to maximally retain nutrients.

Key words: walnut male inflorescence, blanching, proximate composition, amino acids, antioxidant composition, antioxidant activity