Sample Preparation
The obtained shelled walnut kernel was thermally processed according to
a previously described method [9]. The moist-heat processing method
was as following: five hundred grams of shelled walnut kernel was
steamed in boiled water for 15, 20 and 30 min (S15, S20 and S30) at a
temperature of 95 ± 1.5 ºC, which were cooled to room temperature,
frozen for 24 h at -18 ºC, and lyophilized for 48 h at -55 ºC. The dry
heated processing method was as following: five hundred grams of shelled
walnut kernel was roasted in an air fryer (HD9252, Philips, Qingdao,
Shandong, China) at 95 ± 1.5 ºC for 15, 20 and 30 min (R15, R20 and
R30). The raw was as the untreated sample. Total samples were 7 (1
untreated + three moisture heated + three dry heated). The defatted
walnut kernel flour (100 mesh screen) by ground processing contained
about protein 44.85%±1.21%, oil 15.65%±1.08%, moisture content
5.32±0.53% and ash 3.09±0.51%.