Assessment of physico-chemical, antioxidant and antimicrobial activity of porcine blood protein hydrolysate in pork emulsion stored under aerobic packaging condition at 4 ± 1 °C

Highlights

• Incorporation of porcine blood hydrolysate in meat emulsion improve its shelf-life.

• Hydrolysate has effective antioxidant and antimicrobial activity in meat emulsion.

• Utilization of underutilize byproducts give more return to industry & reduce pollution.

Abstract

Present study was conducted to evaluate the effect of porcine blood hydrolysate on lipid oxidative stability and microbial growth in pork emulsion. Three levels of hydrolysate was added into pork emulsion (T1-300 μg/g, T2-600 μg/g and T3-900 μg/g w/w of emulsion) and was compared with control (C-0μg/g) and positive control (PC-200 μg/g BHT w/w). The physico-chemical qualities, antioxidant assay, lipid peroxidation, colour indices and antimicrobial activity were studied. Results revealed that all parameters improved significantly (P < 0.05) with increase in hydrolysate level. However, during storage these parameters decreased significantly (P < 0.05) but were better maintained in treated groups than in control. Pork emulsions with T3-900 μg/g hydrolysate showed overall better storage stability. Microbial challenge test (MCT) results showed that T3 group exhibited significantly (P < 0.05) higher antimicrobial activity against selected microbes. Simillarly, T3 sample also exhibited lower stander plate counts (SPC), coliform counts, yeast and mould counts than other groups. Thus, the addition of hydrolysate in emulsion retards lipid oxidation and antimicrobial proliferation during storage.

Introduction

Blood is an excellent source of protein constituents such as hemoglobin, albumin, globulins, and fibrinogen. Many communities have long been using blood for preparation of traditional products like blood sausages, black puddings, or blood tofu. Numerous studies have also been documented regarding utilization of blood or its components in functional forms such as emulsifying agent, fat replacer, colouring agent, binder etc. for exploring prospects in food products preparations. Emulsifiers are mainly proteineous substances that decrease surface tension and make emulsion more stable by binding protein, fat droplet and water by redistribution of fat globules in emulsion. Emulsifiers are extensively used during the manufacture of emulsion based meat products to obtain good products with quality texture. Verma, Umaraw, and Kumar (2016) documented that emulsifying ability of globulin protein peptic hydrolysates is higher than unhydrolysed globulin.

Meat emulsions are more prone to quality degradation due to their superior nutritional content. The quality downturn of meat emulsion is due to oxidation and microbial deterioration. Meat emulsions are prepared by comminuting meat chunk in the presence of salt, fat and chilled water, resulting in continuous matrix formation where small fat droplets remain dispersed. Increased surface area, disruption of physical barrier, incorporation of air and contamination by equipment enhances fat oxidation and microbial growth in meat emulsions, which become the major predisposing factors for meat quality deterioration, ultimately decreasing its shelf-life. Oxidation of fat is a free radical cascade started by abstraction of a hydrogen ion in unsaturated fatty acids. Oxidation of the fat molecules is also catalyzed by various pro-oxidant like light, temperature and/or exposure of fat droplet membrane to metal ions. It leads to generation of various substrates which have detrimental effects on the physico-chemical, nutritional parameters and sensory attributes of meat emulsion (Karakaya, Bayrak, & Ulusoy, 2011). Microbial growth in meat emulsion also enhances the spoilage as well as causes food borne illness.

To prevent/retard lipid oxidation and microbial growth in meat products, various synthetic antioxidant and antimicrobial ingredients are commonly incorporated to meat model system. Use of these synthetic antioxidants have been limited by various regulatory agencies because of their suspicious detrimental (mutagenic and teratogenic) and carcinogenic effects on consumers health. Thus at present, researchers are trying to find out novel natural compounds having both antioxidant and antimicrobial activity to exploit them as substitutes to artificial preservatives in food products. Protein hydrolysates/peptides are important enzymatic hydrolysis products. Various researchers reported that these have wide spectrum of biological activity like antithrombotic, hypocholesterolemic, antimicrobials, angiotensin-converting-enzyme inhibitory and immunomodulatory properties etc. (Erdmann, Cheung, & Schroder, 2008).

At present some studies have revealed that the protein hydrolysates/peptides recovered from enzymatic hydrolysis of animal/plant protein can be exploited as non-toxic source of natural antioxidant and antimicrobial bioactive compounds. Natural antioxidant potential of meat proteins such as grass carp protein hydrolysate obtained from papain hydrolysis in minced meat system (Li, Luo, You, Shen, & Du, 2012), deboned chicken meat hydrolysates in sausage (Cavalheiro et al., 2014), chicken liver hydrolysate (Chakka, Elias, Jini, Sakhare, & Bhaskar, 2015), housefly larval proteins hydrolysate (Wang, Wang, Dang, Zheng, & Zhang, 2013) and tannery fleshings hydrolysate (Balakrishnan et al., 2011) have been investigated to explore their antioxidant/antimicrobial properties.

Various food safety authorities and legal standards of meat products have recommended or prescribed limited use of conventional chemical preservatives as they might have detrimental effect on consumer health and their excessive utilization has augmented threat of development of resistance in microorganisms that may have serious concerns of food safety in future. Therefore, at present there is an imperative requirement to explore natural preservatives for extension of shelf life of meat and meat products.