The antioxidative potential of jujube extract, pomegranate extract and tocopherol mixed into carboxymethyl cellulose (CMC) solution then coated on roasted and roasted–sonicated peanuts was investigated. The concentration of jujube and pomegranate extracts added into the CMC solution was 1,000 ppm, while synthetic tocopherol was 250 ppm. Antioxidant effect was determined by the measurement of oxidative stability index. After 12 weeks of storage at 35C, the reduction in oxidation was 14.5 and 19.7% for samples roasted–coated with CMC added with extracts of jujube and pomegranate extract, respectively, as compared to uncoated sample (R as a control). Meanwhile, the oxidative stability of samples roasted–sonicated coated with CMC added with extracts of jujube and pomegranate was significantly (P < 0.05) improved by 24.8 and 31.8%, respectively, in relation to the control. However, it was observed that samples with tocopherol did not have any improvement in oxidative stability of the roasted peanuts. Sonication treatment beyond coating improved the storage stability of the samples mixed with jujube extract, pomegranate extract and tocopherol by 10.3, 12.1 and 3.2%, respectively. It is concluded that jujube and pomegranate extracts can control roasted peanut lipid oxidation during storage. PRACTICAL APPLICATIONS This study showed that a combination of power ultrasound treatment and an edible coating of carboxymethyl cellulose mixed with natural plant extracts can be used for delaying the oxidation of roasted peanuts. The delaying development of oxidation compounds in roasted peanuts is very useful to the peanut industry. This process can be used for the preparation of shelf‐stable peanut products for the purpose of reaching distant markets, to be used during extended storage period. Likewise, the peanuts can be packed without the need to modify the packaging atmosphere or use of expensive packages.

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Rancidity due to the lipid oxidation process is a critical factor influencing the quality of roasted peanuts. Sonication in combination with edible coatings added with plant extracts may extend the oxidative stability of peanuts. Peanuts were roasted at 178°C for 15 min, subjected to sonication in hexane for 10 min, and then coated with carboxymethyl cellulose (CMC) solution mixed with rosemary, tea extracts, and α-tocopherol and stored at 35°C for 12 weeks. The oxidative stability of the samples was investigated by measuring the oxidative stability index. Reduction in oxidation of 66.1% and 10.4% was observed for samples roasted and coated with extracts of rosemary and tea, respectively, as compared to uncoated sample. However, the oxidative stability of samples roasted-sonicated and coated with extracts of rosemary and tea was improved by 100.7% and 28.1%, respectively, in relation to the control. Sonication beyond coating improved the oxidative stability of the samples mixed with rosemary, tea extracts, and α-tocopherol by 10.3%, 12.1%, 34.6%, and 17.7%, respectively. The L * , a * , and b * values indicated that the peanut coated with CMC mixed with rosemary, tea extracts, and tocopherol at different concentration levels did not have significant (P < 0.05) color change during the 12-week storage at 35°C.

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 roastedsonicated-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 APPLICATIONSEdible 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 1 Corresponding 469 provided an alternative way for improving the oxidative stability and eventually the shelf life and quality of roasted peanuts. 470 P. WAMBURA ET AL. 472 P. WAMBURA ET AL.

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