Physicochemical, antioxidant, antimicrobial and sensory properties of functional yoghurt supplemented with guava seeds, leaves and pulp extract

Abstract

P SIDIUM GUAJAVA L., popularly known as guava has many medical benefits especially leaves and it considered as waste and seed was by product of juice industry. The aim of this study to investigate the effect of the phenolic and flavonoid compounds on antioxidant and antimicrobial activity of functional flavored yoghurt supplemented with guava extracts (GE) (seeds, green and red leaves and juice). The results showed that all guava extracts have antioxidant activity using (DPPH, ABTS) methods being (seed 89.18%, green leaves 75.41% and red leaves 71.26%) with high total phenolic compounds (TPC) in green leaves 672.42 and in red 658.90 mg GA/100g. Polysaccharide fraction was higher in red guava leaves extract than green leaves and seed extracts, it consists of inulin (2.04%), sucrose (10.84%), stachyose (0.49%), fructose (0.26%), galacturonic (0.35%), sorbitol (0.14%). Also, guava extracts have antibacterial activity against tested bacteria. Addition of guava extracts to yoghurt especially (pulp, leaves) improved sensory properties, increased total solids and protein content, didn't affect the acidity and pH. All yoghurt samples were protected from growth of spoilage and pathogenic bacteria and improved growth and viability of lactic acid bacteria (LAB). During the cold storage, (TPC) and individual phenolic contents and antioxidant activity of GE-fortified yoghurt gradually and significantly increased (p<0.05). Antioxidant activity of GE-fortified yoghurts is highly related to TPC. The results showed that GE can be used as a natural antioxidant ingredient and can be used for the production of functional dairy products to improve nutritional value and biological activity.

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“…Furthermore, the GC-MS analysis showed several bioactive compounds with important biological activity in ABP like Cinnamic acid, 4-hydroxy-3-methoxy (which has a promising potential as anticancer according to Mumtaz et al 2021), 9,10-Secocholesta-5,7,10(19)triene-3,24,25-triol, (3α,5Z,7E)-(which has anti-eczematic, anti-osteoporotic and inhibits prostaglandin-E2 9-reductase (Brintha et al, 2017), 1-Monolinoleoylglycerol trimethyl silyl ether (antimicrobial activity according to Al Bratty et al (2020), Sarreroside (which has respiratory analeptic effect, anti-cancer, antiprotozoa, dementia treatment, hepatoprotectant, and anti-eczematic according to Brintha et al (2017), Oxiraneoctanoic acid, 3-octyl-, cis-(Actually, Hussein et al (2016a) showed that Oxiraneoctanoic acid, 3-octyl-,methyl ester had antibacterial activity), 7,8-Epoxylanostan-11ol, 3-acetoxy-(which has antimicrobial, antiinflammatory effect according to Hassan et al (2014); Lee et al (2013), and n-Butyl ricinoleate (it was mentioned to the anti-bacterial and antimycobacterial properties of ricinoleic acidderived compounds (Kuppala et al, 2016).…”