IMPROVEMENT OF OXIDATIVE STABILITY OF ROASTED PEANUTS BY EDIBLE COATINGS AND ULTRASONICATION

In this study, an innovative method was developed to improve the shelf life of roasted peanuts. Sonication was combined with edible coating for enhancing the oxidative stability of roasted peanuts. Georgia green runner peanuts were roasted, subjected to sonication and then coated with whey protein isolate (WPI), ZEIN and carboxymethyl cellulose (CMC). Relative to the control, the oxidative stability of roasted-coated samples was improved by 80, 38 and 5% for CMC, WPI and ZEIN coating, respectively, while roasted-sonicated-coated samples were improved by 91, 52 and 27% for CMC, WPI and ZEIN coating, respectively. Sonication prior to coating resulted in 11, 14 and 22% improvement beyond the CMC, WPI and ZEIN coatings, respectively. Texture analysis showed there were no significant differences ( P <  0.05) in peanut texture between the treated and the control. Color results showed the HunterLab color parameters L, a, and b for most of the treatments did not have significant differences ( P <  0.05) compared with the control.

PRACTICAL APPLICATIONS

Edible coatings used in this study (carboxymethyl cellulose, whey protein isolate and ZEIN) were capable of acting as oxygen barriers to reduce peanut lipid rancidity. This research demonstrated the potential of power ultrasound to remove lipids from the peanut surfaces and improve coating adhesion. The texture and the color of coated peanuts did not change over the storage period. This study indicated that edible coatings in combination with sonication provided an alternative way for improving the oxidative stability and eventually the shelf life and quality of roasted peanuts.