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

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 (SCO2), 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.

The effects of production methods and storage on the chemical constituents of apple pekmez.

The purposes of this study were to investigate the effects of two different pekmez production methods namely open pan evaporation (OPE) and vacuum evaporation (VE) on the final products, and to observe the changes in constituents as well as aromatic components after 4 months of storage. The initial and poststorage (4 months) 5-hydroxymethyl furfural (HMF) content in OPE apple pekmez were respectively 5.48, and 7.04 mg/kg. No HMF was detected in VE apple pekmez. Both initial and poststorage content of phenolic compounds was higher in VE pekmez compared to OPE pekmez. The effects of production methods and storage time were statistically significant on phenolic compounds in apple pekmez. The content of all analyzed minerals except calcium has significantly decreased in pekmez compared to raw material on dry weight basis. OPE resulted in a 55.97 % loss in the amount of ascorbic acid, whereas the loss in VE has been 23.45 %. Poststorage loss in ascorbic acid has respectively been 69.54, and 89.28 %, for VE and OPE samples. None of the aromatic components of fresh apple was detected in pekmez.