# Influence of LAB Fermentation on the Color Stability and Oxidative Changes in Dry-Cured Meat
## 1 Introduction  
For centuries, human nutrition has been based on meat. Meat is a source of protein, vitamins, minerals, and other bioactive compounds. Due to its chemical composition, such as high protein content, meat tissue is a potential medium for pathogens. Therefore, to extend the shelf life of meat, fermentation has long been used as a preservation method. Besides extending the shelf life, fermentation produces specific compounds that are responsible for the taste and smell of the fermented product [1]. Thus, fermentation is used as a biopreservation method although nowadays meat is fermented mainly to enhance taste and flavor [2]. There are no clearly defined starting and end stages of the fermentation process. The moment when lactic acid bacteria (indigenous or industrial) begin to grow and multiply on meat and when carbohydrates are converted into lactic acid are considered the starting stage of fermentation. The moment when microflora nutrients are exhausted is considered the end stage. In most industries, commercial and industrial micro-organisms are used as starter cultures in fermentation, such as lactic acid bacteria (LAB), especially Lactobacillus, whose fermentation properties result in a number of desired product changes and increase fermentation efficiency, thus leading to consistent product quality [3, 4]. However, meat can also be fermented using environmental strains, but this process is difficult to control because of the way in which microflora develops and its final effects on the product are not certain. The primary advantage of using LAB in meat fermentation is their ability to break down carbohydrates into lactic acid, which lowers the pH of meat and acidifies it. Other studies have reported that the action of endogenous proteases is enhanced with the decrease in the pH of the meat matrix [5; 6]. In addition, a low pH limits the growth and development of undesirable microflora in the meat, thereby increasing the microbiological purity of fermented meat products. The reduction in pH also suppresses the growth of spoilage bacteria, which are responsible for the poor microbiological quality of end products on the one hand and excessive proteolysis leading to texture defects on the other hand [2; 7; 8]. In addition, under low pH conditions, meat proteins undergo gelation, which improves the texture of the meat in dry-cured products [9]. Furthermore, fermentation enhances the organoleptic properties of the final product, giving it a slightly sour taste. During meat fermentation, complex processes shape the sensory perception of smell which consumers define as desirable. In addition, LAB reduces nitrate V to nitrite III in cured products, which is further broken down into nitric oxide, which in turn interacts with myoglobin and forms nitrosomyoglobin. Nitrosomyoglobin is responsible for the characteristic red color of the fermented meat products [10]. The enzymes derived from LAB also play a crucial role as they reduce the peroxide content and thus reduce the rancidity of fats and stabilize the color of products [11; 12; 13]. For instance, Lactobacillus plantarum AR13, Pediococcus pentosaceus AR243, and L. plantarum AR501 isolated from Chinese fermented foods showed high activity in scavenging \(\alpha\)-diphenyl-\(\beta\)-picrylhydrazyl and hydrogen radicals and a strong inhibition of peroxidation [14]. The degree of advancement of the oxidation processes in meat products most often relates to changes in fat. The most popular is the thiobarbituric acid (TBA) reactive substance test (TBARS). Lipid oxidation proceeds through the free radical chain mechanism, yielding many end products, in particular aldehydes. One of the best-studied aldehydes is malondialdehydedehyde (MDA), which reacts with the acid with TBA. Therefore, it is considered a marker of oxidative damage within the fat fraction [15]. Besides fats, proteins are also an important component of meat.