Study of the effect of sodium alginate coating containing pomegranate peel extract on chemical, sensory and microbial quality of walnut kernel

Abstract

Background: Due to the adverse effects of artificial preservatives on food and its harmful effects on human health, researchers have been considering replacing these materials with natural substances. In this study, the effect of pomegranate peel extract (PPE) on the stability and antifungal activity of the walnut kernel was studied. Methods: The pomegranate peel was extracted by the solvent and water-solvent method. The extracted sap was evaluated using the antioxidant assay by 2,2-diphenylpicrylhydrazyl (DPPH) assay. The results showed that the extracted sap had 40.11 mg/g dry phenol and 47.27% free radicals scavenging. Four concentrations (0%, 2%, 6%, and 10%) of pomegranate liquid extract were prepared and studied for 90 days for the walnut kernel coating. Walnut kernels were coated on days 1, 15, 30, 60, and 90, and examined for moisture, acidity, peroxide, conjugated diene, and anisidine tests. Data were analyzed using SPSS version 21. Results: By increasing the extract concentration from 2 to 10%, the stability of the walnut kernel during storage was increased. Acidity in the samples with 10% PPE coating, decreased from 0.18 to 0.11 on the first day until the 15th day, and increased to 0.48 from day 15 to 90. The results showed that the moisture content and acidity increased with increasing the extract concentration. By increasing the extract concentration up to 10%, the sustainability indices, including peroxide, anisidine, and conjugated diene were significantly decreased. At 90 days, by increasing the concentration of pomegranate extract from 2% to 10%, the count of molds and yeasts was reduced from 3.59 to 2.29 CFU/g. The count of molds and yeasts in the uncoated samples was 5.81 CFU/g. Conclusion: According to the results, PPE can increase the stability and antifungal activity of walnut, therefore, the health quality of the product increases.

Utilization of pomegranate peel extract as antifungal coating agent against Fusarium oxysporum on tomatoes

“…Therefore, the coated tomatoes have limited fungal growth than uncoated ones (Azam et al, 2020). Similar results were reported by Davoodi and Naji (2018), who studied the pomegranate peel addition in alginate coating. As the concentration of pomegranate peel increased from 2 to 10%, the decrease in mold and yeast count was observed.…”

“…Therefore, the coated tomatoes have limited fungal growth than uncoated ones (Azam et al, 2020). Similar results were reported by Davoodi and Naji (2018), who studied the pomegranate peel addition in alginate coating. As the concentration of pomegranate peel TA B L E 3 Effect of treatments and storage days on ascorbic acid and lycopene of coated and uncoated tomatoes F I G U R E 3 Effect of treatments and storage days on TPC (log CFU/g) of tomato, T o = 0% pomegranate peel extract, T 1 = 0.5% pomegranate peel extract, T 2 = 1.0% pomegranate peel extract, T 3 = 1.5% pomegranate peel extract, T 4 = 2.0% pomegranate peel extract, T 5 = 2.5% pomegranate peel extract.…”

Vegetable Additives in Food Packaging Polymeric Materials

“…Coating treatments could delay the declining of the total phenolic content, flavonoids, and anthocyanins content and antioxidant activity in various fruits as was found for strawberries coated with alginate containing carvacrol and methyl cinnamate (natural antimicrobials) [199], walnut kernel coated with sodium alginate coating containing pomegranate peel extract [200], and strawberries coated with chitosan containing peony extracts [201].…”