Virtual Conference
Nutrition 2022

Mabrouka Hitana

Arid Regions Institute, Tunisia

Title: Protective activity of edible films added with Rhanterium suaveolens extracts on the oxidation of raw meatballs during cold storage

Abstract

Oxidation is one of the main causes of deterioration in the quality of meat. Due to grinding of muscle tissue, raw minced meat is highly susceptible to oxidative deterioration. To counteract this, natural antioxidants may be added directly to the food matrix, or incorporated into protective films.  Whey protein isolate was thus produced edible films intended to enhance raw meat balls protection during refrigerated storage. Indeed, this kind of film acts as an oxygen and water barrier, and thus limits colour changes and moisture loss. To boost the antioxidant effect, we added to the film formulation phenolic-rich extracts of Rhanterium suaveloens, a spontaneous plant from the Asteraceae genus, growing in the Tunisian desert.
70% acetonic extracts of Rhanterium suaveloens flowers and stems were prepared using ultrasound-assisted extraction. Their phenolic contents were assayed using Folin-Ciocalteu method. The identification and the quantification of phenolic compounds were assessed by HPLC-ESI-MS. A total of 23 metabolites including phenolic acids and flavonoids were identified and reported for the first time in R. suaveolens species. Chlorogenic acid and its derivates; 3.4-di-O25 caffeoyquinic and 4.5- di-O-caffeoyquinic acids were identified as the major compounds in the flowers and the stems extracts. On the other hand, quercetin-3-O-galactoside was found to be the major flavonoids in the studied extracts. Their potential as antioxidants was first evaluated in vitro using DPPH, ABTS and FRAP assays showed promising results. These extracts were then incorporated into whey protein-based films (4% of the film-forming solution). The oxidation of meatballs protected or not by these films, was monitored under prooxidant atmosphere and cold storage. On days 0, 2, 8 and 10, meat lipids were extracted and their peroxide indices, conjugated dienes, metmyoglobin and T-BARS contents were determined. While all oxidation indicators were significantly reduced when films were used compared to control meatballs, only a slight non-significant effect of the extracts addition was observed.
Despite promising in vitro antioxidant effects, Rhanterium suaveolens extracts incorporated into edible films did not improve their antioxidant activity. As the plant also showed an interesting in vitro antimicrobial activity, its potential of valorisation as natural food preservative will also be investigated.

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