Use of pomegranate peel extract incorporated zein film with improved properties for prolonged shelf life of fresh Himalayan cheese (Kalari/kradi)

Highlights

• Packaging films with added pomegranate peel extract (PPE) were used for packaging of kalari cheese.

• The film with added PPE retarded the cheese spoilage.

• The film with added PPE retarded the oxidation of fats and proteins of cheese.

• The film can be suggested as potential active packaging for fresh cheeses.

Abstract

Zein films added with different concentrations (0, 25, 50, & 75 mg/ml of film forming solution) of pomegranate peel extract (PPE) were designed and characterized as a novel packaging material for Himalayan cheese (kalari). With increase in PPE concentration, tensile strength, elongation at break, total phenolic content and antioxidant activity of zein films increased whereas film solubility, water vapor transmission rate decreased and thickness remained constant. PPE containing films exhibited inhibitory activity against all tested pathogenic strains (Escherchia coli, Pseudomonas perfringens, Micrococcus luteus, Enterococci faecalis, Staphylococcus aureus, Proteus vulgaris and Salmonella typhii). ATR-FTIR spectra showed interactions between PPE polyphenols and zein film. Kalari wrapped in PPE containing zein films were found to have low protein and lipid oxidation products during storage when compared to film without PPE. Films were also found to inhibit spoilage microorganisms in kalari whereas number of Lactic acid bacteria was enhanced. The study validated that incorporation of fruit waste (pomegranate peel in this case) which are rich in polyphenols, in zein film offers a promising source for inducing it the ability to control cheese spoilage caused either by the bacterial contamination or protein and fat oxidation, without affecting its overall sensory characteristics.

Introduction

Kalari is an important traditional cheese of Himalayan region of Jammu and Kashmir made from buttermilk with profound health benefits. It is a fresh cheese, with bright white and smooth surface and is rapidly spoiled (5–7 days) when stored under ambient conditions (Mushtaq, Gani, Masoodi, and Ahmad, 2016). Soft cheeses are at high risk of safety because of their negligible hurdle effect against survival/growth of pathogenic bacteria. Thus controlling bacterial contamination of such cheese types is necessary and their preservation and safety could be achieved by packaging systems with active ingredients (Youssef, El-Sayed, Salama, El-Sayed, & Dufresne, 2015).

Traditionally, Kalari cheese is distributed without any packaging but in some places it is commercialized in petroleum based packages, to prevent external contamination that may result in its quality deterioration. In present scenario, consumers are limiting the use of foods which contain artificial additives (colorants, flavor improvers or preservatives) and are packed in synthetic packaging materials because of their concern about deteriorating health and environment (Debiagi, Kobayashi, Nakazato, Panagio, & Mali, 2014). It is thus essential to channelize such optimal materials that have good film forming properties, are environmentally safe and contains natural preservatives (Llana-Ruiz-Cabello et al., 2015).

Plant extracts with high bioactivity incorporated in bio-based packagings have been and are developed to curb the usage of synthetic polymers (Llana-Ruiz-Cabello, Pichardo, Maisanaba, et al., 2015; Ashwar et al., 2014; Salarbashi et al., 2014). An interesting biopolymer that has excellent film forming properties but is less extensively investigated is the unique maize protein, zein. It has the GRAS (Generally Recognized as Safe) recognition given by U.S. Food and Drug Administration (U.S. Department of Health and Human Services, 2015). Zein films have shown useful characteristics in terms of permeability, glossy appearance, high hydrophobicity, low water solubility, high thermal stability and resistant to microbial attack, which make them a promising material in the field of bio-packaging (Pena-Serna, Penna, & Filho, 2016; Gaona-Sanchez et al., 2015). But, brittleness and low flexibility of zein films limit their use as freestanding film for food packaging (Zhang, Luo, & Wang, 2011).

Many investigations have been conducted so far to overcome these problems by either blending zein with other biopolymers or incorporating ingredients of varying chemistry like, organic acids, fatty acids, sugars or other plasticizers (Pena-Serna, Penna, & Filho, 2016). Studies targeting addition of bioactive compounds to improve its mechanical properties are scarce; however, bioactive compounds are being incorporated with the aim of developing active packaging. A study carried out by Arcan and Yemenicioglu (2011) revealed that addition of natural bioactive phenolics (catechin, gallic acid, ferulic acid, flavone, quercetin or hydroxy benzoic acid) helps in the development of highly flexible zein films with added activity against oxidation and microbial spoilage. These bioactive compounds can be easily made available to the packaging industry by extracting phenolics from by-products of fruit industry. This will not only make the packaging cost effective but will also help in keeping our environment clean.

Pomegranate peel is a by-product of the pomegranate juice industry. It possesses the highest bioactivity among the other fruit components. It constitutes about 40% of the whole fruit (Panichayupakaranant, Tewtrakul, & Yuenyongsawad, 2010). Pomegranate peel is rich in phenolics, flavonoids and tannins (Malviya, Arvind, Jha, & Hettiarachchy, 2014) reflect its possible use as a flexibility improver and bioactivity inducer in zein films. The objective of the present study was to develop an active zein film with improved mechanical properties by utilizing industrial waste and its usage as a packaging material for prolonged shelf life of traditional Himalayan cheese (Kalari).