Improvement of shelf-life of buffalo meat using lactic acid, clove oil and vitamin C during retail display

Abstract

Buffalo meat steaks dipped in either (1) distilled water (control), (2) lactic acid (LA), (3) LA + clove oil (clove), or (4) LA + clove + vitamin C (Vit C) were displayed at 4 ± 1 °C, illuminated by a standard fluorescent lamp. The pH, 2-thiobarbituric acid reactive substances (TBARS), instrumental colour (CIE L^∗, a^∗, b^∗), aerobic plate counts (APC), psychrotrophic counts (PPC), coliform counts and sensory colour and odour were determined up to 12th day of display at 3 days interval. Results showed that, all the treatments have significantly (P < 0.05) reduced the TBARS values compared to control. Among treatments, use of LA + clove has exhibited significantly (P < 0.05) lowest TBARS values throughout display period than others. Buffalo meat steaks treated with either LA + clove or LA + clove + Vit C had significantly (P < 0.05) lower APC, PPC and coliform counts than control or LA treated samples. LA + clove + Vit C treated samples maintained significantly (P < 0.05) higher a^∗ and b^∗ values during display as well as improvement in sensory colour and odour than others. Treatment with either LA + clove or LA + clove + Vit C extended the display life of buffalo meat steaks at 4 ± 1 °C. There appears to be a significant advantage to using LA + clove or LA + clove + Vit C over LA alone.

Introduction

Microbial growth and oxidative rancidity are the major problems causing shelf life quality deterioration in meat and meat products. Biopreservatives can be useful in extending shelf life of foods, by reducing or eliminating survival of pathogenic bacteria and increasing overall quality of food products through inhibition of oxidative rancidity. Clove is a naturally occurring spice, which has been shown to possess antioxidant and antimicrobial activity in food products. The oil of clove is used in dentistry as a local antiseptic. The terpenoids in clove are thought to exert inhibitory action against microorganisms by membrane disruption (Lambert, Skandamis, Coote, & Nychas, 2001). Its inhibitory action against various gram positive and gram negative bacteria in meat and meat products is also recorded (Mannie, 1999).

Eugenol, the essential oil of clove, is a 2-methoxy phenolic derivative, which has been reported to possess 90% of the antioxidant activity of butylated hydroxy anisole (Cort, 1974). Al-Jalay, Blank, Mc Connel, and Al-Khayat (1987) reported the highest antioxidant index for clove followed by rose petals, cinnomon, nutmeg and other spices in pastourma sausages. He further reported that clove was the strongest antioxidant in an oil/water emulsion. However, to have an inhibitory effect on microorganisms higher level of cloves are required in the formulation (Mannie, 1999). But crude extracts of many spices and herbs at higher level impart an objectionable colour, odour and taste to food (Draughon, 2004). The use of spices with other food ingredients, such as sodium chloride, sugar and organic acid might provide a synergestic effect in controlling microbial growth (Giese, 1994).

Lactic acid is a generally regarded as safe (GRAS) antimicrobial agent commonly used in meat and meat products for decontamination. However discolouration continues to be a major problem associated with organic acid decontamination of meat cuts especially at higher levels (Kotula & Thelappurate, 1994), and improving the colour stability of meat is a matter of concern to retailers.

Vitamin C has been used as a steak surface treatment either alone or in combination with other antioxidants to stabilize meat colour during display (Mitsumoto, Cassens, Schaefer, & Scheller, 1991). Various natural antioxidants have also been used along with ascorbic acid for preventing food oxidation (Shahidi & Wanasundara, 1992). However depending on conditions, ascorbic acid can act as a prooxidant or an antioxidant (Elliott, 1999).

Although numerous studies have been done in vitro to evaluate the antioxidant and antimicrobial activity of clove, only a few studies have been done with food products. Furthermore, use of clove along with some organic acids or vitamin C in meat and meat products has not been reported so far. However, use of clove oil along with LA may give synergistic antioxidant/antimicrobial effects and inclusion of Vit C also might stabilize the colour as well. Therefore, the present study was undertaken to evaluate the effect of lactic acid, clove oil and vitamin C for the improvement of buffalo meat shelf life during retail display at 4 ± 1 °C.