Effects of packaging method and storage time on the chemical, microbiological, and sensory properties of Turkish pastirma – A dry cured beef product

Abstract

The effects of packaging method (aerobic packaging (AP), vacuum packaging (VP) or modified atmosphere packaging (MAP)), the form of pastirma (sliced or non-sliced) and storage time (0, 15, 30, 60, 90 or 120 days) on the chemical, microbiological and sensory properties of a Turkish pastirma were investigated. Overall, MAP preserved chemical, microbiological and sensory properties of Turkish pastirma better than AP or VP. Very high correlation coefficients (almost all >0.90) were observed between subjective quality parameters (sensory properties) and objective quality parameters (TBARS, hexanal content, L^∗, a^∗, and b^∗), which suggests that sensory panel was able to determine the quality changes over storage time precisely. Based on the results of this study, MAP should be the preferred choice of packaging in order to preserve overall quality of Turkish pastirma and its implication for pastirma packaging may increase pastirma’s current share in the processed meat product market.

Introduction

Pastirma, a popular dry cured beef product made from whole muscle can be considered an intermediate moisture food. To produce pastirma, beef meat (mostly from loin) is utilized. All the exterior fat and connective tissue need to be removed from the meat, and then the resultant meat is cured, dried, pressed and coated with çemen paste (Aksu and Kaya, 2002, Tekinşen and Dogruer, 2000). The characteristic flavor and aroma of pastirmas can be attributed to the ingredients used in its processing namely fresh mashed garlic, red pepper, paprika, and ground fenugreek (Trigonella foenum graecum) seeds (Gökalp et al., 1999, Tekinşen et al., 1999). This mixture is known as çemen (cement) in Turkey, and is reported to improve appearance, color, texture, taste, and flavor of pastirma and. It is also effective against microbial contamination and serves as a barrier to excessive drying of pastirma (Işıklı & Karababa, 2005).

Pastirma, used to be produced and consumed in the Kayseri region of Turkey, but is now available in any nationwide retail market in Turkey. Consumers have recently shown considerable interest in sliced meat products (Aksu, Kaya, & Ockerman, 2005). Sliced pastirma has a great potential in the food market in general. However, it is important that pastirma reach market safely and has extended shelf life, high yield and is microbiologically stable.

Hermetic packaging has recently been popular for the conservation of cured meats. Vacuum packaging (VP) has been used in the meat industry for quite a long time and been accepted by the consumers (Borch et al., 1996, Samelis et al., 2000). For example, in the case of Galician chorizo sausage, VP is the most widely used method (Fernandez-Fernandez, Rozas-Barrero, Romeo-Rodriguez, & Vazque-Oderiz, 1991). The VP process involves putting the product in a bag, and the air is then evacuated and the bag is evacuated without the addition of any other gas. The bags used in VP are typically made from a flexible plastic film that has low gas and water vapor permeability and the plastic film generally adheres closely to the product and it may also be called skin tight (Lundquist, 1994). However, VP is reported to cause liquid exudation and product deformation in soft meat products (Santos et al., 2005).

To overcome this problem and to develop bright red color (if oxygen is used in the gas mixture), an alternative packaging method known as modified atmosphere packaging (MAP), was developed. MAP has started becoming more common and has successfully been applied to different raw and processed meat products (Ahvenainen et al., 1990, Pexara et al., 2002). In this method, the product is placed into the pack, and the air is removed and replaced with a mixture of gases. Then the package is hermetically sealed. The most frequently used gases are oxygen, nitrogen, and carbon dioxide, but other gases such as carbon monoxide, nitrous oxide, and sulfur dioxide may also be used (Farber, 1991). Carbon dioxide has been reported to be extensively used in raw and cooked cured products because it has a strong inhibitory effect on microorganisms (Borch et al., 1996, Sørheim et al., 2004). Researchers reported the efficacy of carbon dioxide (20–30%) against aerobic spoilage bacteria in packaged meat products (Sørheim et al., 2004). Nitrogen does not have a strong inhibitory effect on microorganism, and it is generally used in MAP as a filler gas. Researchers reported the efficacy of carbon dioxide (20–30%) against aerobic spoilage bacteria in packaged meat products (Sørheim et al., 2004). As compared to MAP or VP, aerobic packaging (AP) is reported to decrease shelf life and quality of most foods due to higher oxygen levels (Aksu et al., 2005).

The shelf life of MAP meat products as compared to their vacuum packaged counterparts was poorer in some studies (Pexara et al., 2002, Santos et al., 2005). However, Santos et al. (2005) reported lower Pseudomonas and Enterobacteria count for the samples packaged in a MAP package containing 50% or 80% carbon dioxide than for the samples packaged by VP.

The objective of this study was to investigate the effects of packaging method (AP, VP or MAP), form (sliced or non-sliced) and storage time on the microbiological, chemical, and sensory properties of Turkish pastirma and to investigate whether MAP provides better pastirma quality and shelf life stability than AP and/or VP.