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With the drying process, the water activity and moisture content of the foods are reduced, so the growth of microorganisms in the foods is largely prevented/postponed. But low-aw foods should not be considered sterile they can be contaminated by fungi and other contaminants during the drying process under unhygienic conditions. If drying is not done to a sufficient degree of moisture during food processing and storage, where dried foods are processed, sometimes the minimum value is reached for the growth of microorganisms. In dry foods, some pathogens, yeast and molds can continue to grow during storage, transport and transportation until the sale and they causing spoilage. They can even cause health problems if enough pathogen or spore cells remain viable. Considering this situation today, it is attempted to obtain high-quality dried foods with good microbiologically and chemically properties. For this purpose, various drying methods have been developed. Most studies suggest that when foods are pre-treated with the ascorbic acid or sodium metabisulfite or applied with various combined methods such as UV irradiation, supercritical carbon dioxide (SCO 2 ), low-pressure superheated steam drying (LPSSD), and infrared (IR) drying, they can be effective on inactivation of microorganisms. We have reviewed in this study how these methods made dried products efficient of microbial inactivation and microbiologically safe. Keywords Food safety • Microbial inactivation • Bacterial survivor • Drying methods • Dried fruits and vegetables • Emerging technologies in food processing * Duygu Alp

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In an intestinal system with a balanced microbial diversity, lactic acid bacteria (LAB) are the key element which prevents the colonization and invasion of gut pathogens. Adhesion ability is important for the colonization and competition abilities of LAB. The aim of this study was to determine the adhesion and competition abilities of LAB by using a whole-tissue model. Indigenous strains were isolated from spontaneously fermented foods like cheese and pickles. The aggregation and competition abilities of the isolates were determined, as well as their resistance to gastrointestinal conditions. Four Lactobacillus strains and one Weissella strain were found to be highly competitive against three major gut pathogens, namely Clostridium difficile , Listeria monocytogenes and Salmonella Enteritidis. Tested strains decreased the number of pathogens to below their disease-causing levels. According to the results, the numbers of C. difficile and L. monocytogenes bacteria decreased by an average of 3 log, and their adhesion rates decreased by approximately 50%. However, the number of S. Enteritidis bacteria was decreased by only 1 log compared with its initial number. We thought that the weak effect on Salmonella was due to its possession of many virulence factors. The results showed that natural isolates from sources other than human specimens like the Weissella strain in this study were quite competent when compared with the human isolates in terms of their adhesion to intestines and resistance to gastrointestinal tract conditions. It was also revealed that a whole-tissue model with all-natural layers can be successfully used in adhesion and competition tests.

Petroleum-based packaging (PBP) materials cause environmental pollution and toxic substance accumulation because they cannot decompose in nature for a long time. To prevent these problems, a wide variety of food packaging materials emerge as alternatives to PBP. Researchers have already discussed how polysaccharides and biopolymer-based nanocomposites are used in the development of food packaging films. This chapter, we will introduce how the microorganism-generated biopolymer, polyhydroxyalkanoates (PHAs) to be specific, is used in food packaging. PHAs, have positive social and environmental impact when compared to traditional plastics in terms of production and recycling. Considering that industrial wastes contain high quality polysaccharides, essential oils and proteins, using them in the production of biodegradable packaging will both reduce environmental problems and provide economic gain by reprocessing the wastes into products with higher added value. However, it has some disadvantages in competition with synthetic plastics and applications as biomaterials due to some properties such as poor mechanical properties, high production costs, limited functionality, incompatibility with conventional heat treatment techniques and susceptibility to thermal degradation. In this chapter, we will discuss the future and potential difficulties that may be experienced in the production or dissemination of PHA as a packaging material.