Abstract:

Objective: To investigate the effect of different processing methods on immunoregulation and cholesterollowering
activity of sweet potato glycoprotein SPG-1. Methods: The influence of heat, acid-alkali, ultraviolet and microwave
treatment on immunoregulatory activities, including macrophage phagocytic function, phagocytic function and serum
hemolysin content, and cholesterol-lowering activity of SPG-1. Results: Heat and acid-alkali treatments were obviously
affect the immunoregulation and cholesterol-lowering activity of SPG-1. The phagocytic index (k), acid α-naphthy acetate
esterase (ANAE) positive rate, serum 50% hemolytic value (HC50) and serum cholesterol reduction rate (ΔTC) of SPG-1
were significantly decreased (P < 0.05 or P < 0.01) by heat (higher than 100 ℃), acid (pH smaller than 3.5) and alkali (pH
above 7.5) treatments when compared with the control group. Ultraviolet treatment did not affect k value or ΔTC (P > 0.05),
although resulting in a significant difference in both parameters compared with the control when conducted for more than
60 s (P < 0.05 or P < 0.01). Conclusion: SPG-1 should avoid heat treatment at high temperature (> 70 ℃) and long-time
microwave treatment (> 60 s), and the appropriate pH range should be 3.5–7.5.

Key words: sweet potato glycoprotein, processing, immunoregulation, cholesterol