Comparative Analysis of Nutritional Constituents, Antioxidant and Antimicrobial Activities of Some Common Vegetable Wastes

Abstract

Vegetables are intrinsic to a healthy diet. But the peels are discarded as food waste, unknowing of their potential as the source of bioactive compounds. The study aims to find the nutritional constituents, antioxidant and antimicrobial activity of these food wastes. Here we make a comparative investigation among the five underutilized vegetable parts namely, Solanum tuberosum (Potato peel), Cucumis sativus (Cucumber peel), Musa acuminata (Unripe Banana peel), Brassica oleracea (Cauliflower stem), Lagenaria siceraria (Bottle gourd peel). After the primary screening, including proximate and qualitative analysis, the quantification of primary and secondary metabolites as well as minerals was estimated by different standard methods. The antioxidant potential was evaluated by both DPPH and H2O2 radical scavenging assays. Antimicrobial activity was analyzed by Kirby Bauer disc diffusion method against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) strains of bacteria compared with positive and negative controls. From the proximate analysis, the highest moisture and water content were found in the peel sample of Lagenaria siceraria. Out of ten qualitative tests, protein, fatty acid, flavonoid, alkaloid and xanthoprotein were detected in all five samples. Among the quantitative estimations, Lagenaria siceraria showed the highest amount of polysaccharides (85.82±0.12 mg DE/g DW), ascorbic acid (2.48±0.14 mg AAE/g FW), thiamine (24.46±0.13 mg TE/g DW), polyphenols (86.36±0.10 mg GAE/g DW), flavonoids (49.59±0.07 mg QE/g DW), minerals like K, Ca and Mg and 72.35±0.40% inhibition by DPPH. Simultaneously a significant amount of protein (63.59±0.13 mg BSAE/g FW), the amino acid (7.84±0.02 mg AAE/g DW), minerals like Na, Zn and B and 88.76±0.10% inhibition by H2O2 were found in Cucumis sativus. At a higher concentration, all samples were exhibited significant antimicrobial activity which laid out a strong correlation with previously screened phytonutrients and antioxidants. The overall findings suggested that these underutilized vegetable parts can be utilized in the processing of potential functional foods as well as pharmaceuticals rather than thrown out as agro-waste.

Stimulatory effect of Phyllanthus amarus extract on growth performance, haemato-biochemical, anti-oxidative status and immune response of African catfish, Clarias gariepinus

“…The present study has demonstrated antibacterial activities of crude PAE against A. hydrophila, P. aureginosa and P. orescens, with the methanol extract exhibiting similar activity relatively to the synthetic antibiotic used in aquaculture. Our observations in the present study is similar to previous authors(Okigbo and Igwe, 2007;Oluwafemi and Debiri, 2008;Bhat et al, 2015;Biswas et al, 2020, Adeniyi et al, 2021b) who observed signi cant antimicrobial effect of Phyllanthus amarus against some pathogenic and food poisoning organisms.The growth-promoting potential of PAE has been discovered in the present study. The enhanced growth performance might have been due to ability of P. amarus to stimulate digestibility of nutrient by presence of some phytochemical compound in the plant, including lignin glycosides called phyllanthostatin(Pettit et al, 1990), avonoids like quercetin and kaempferol (El-Mekkawy et al, 1995), ellagitannins like geraniin and furosin(Miguel et al, 1996), niruroidine (Quian-Cutrone et al, 1996) as well as nirtetralin A(Wei et al, 2012).…”

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“…AAS was used to determine the mineral composition. The values obtained in mg/L of dry weight of the powdered sample 26 .…”

A second life for fruit and vegetable waste: a review on bioplastic films and coatings for potential food protection applications

“…87 As mentioned before, plant wastes often contain residual amounts of different bioactive compounds (e.g., glucosinolates, phenolic acids, and flavonoids) characterized by remarkable health-promoting properties with strong immunomodulatory, antimicrobial, antioxidant, and anti-inflammatory actions. 88 These bioactive compounds need to be recovered from the waste source through feasible and efficient extraction processes. The most common and easily implementable extraction process is conventional solid-liquid extraction.…”