The microbiological quality of various foods dried by applying different drying methods: a review

Abstract

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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“…Food is classified as low acidity (pH > 4.50), acid (pH in the range of 4.00 to 4.50) and very acid (pH < 4.00). The information about acidity is important in the characterization of food and in the realization of after-harvest studies since it is related to the proliferation of microorganisms, adding, therefore, to the final quality of the products (Alp & Bulantekin, 2021).…”

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“…Also, the dried fruits take a much smaller space during packaging and have a long shelf life (Šumić et al, 2016) Sun-drying has been used for ages to dry foods. However, its major shortcomings are unpredictable weather, high drying time, inconsistent product quality, and product loss due to birds and pests (Alp & Bulantekin, 2021;Khaing Hnin et al, 2018).Other convective drying methods with controlled drying conditions like tray drying are also commonly used in the industries. During convective drying, the hot air comes in direct contact with the food products, causing a change in color due to oxidation.…”

“…Also, the dried fruits take a much smaller space during packaging and have a long shelf life (Šumić et al, 2016) Sun-drying has been used for ages to dry foods. However, its major shortcomings are unpredictable weather, high drying time, inconsistent product quality, and product loss due to birds and pests (Alp & Bulantekin, 2021;Khaing Hnin et al, 2018).…”