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Pickling is one of the methods for preserving food. However, this term may refer to both types of products, that is, to those subjected to lactic acid fermentation and to marinated ones (acidified) that are usually produced by the addition of acetic acid. Various raw materials are subjected to lactic acid fermentation (vegetable and animal origin), which yields food products with high nutritional and dietary value. In many regions of the world, the process of lactic fermentation is also traditionally used to preserve fruiting bodies of edible mushrooms. Mushrooms are appreciated for their organoleptic qualities as well as the presence of many different bioactive substances exhibiting healing and health‐promoting properties. This article reviews the literature related to the use of lactic fermentation in the process of mushroom preservation. Particular attention has been paid to the aspects of the technological process and its impact on the quality and suitability of the final products. Moreover, research results concerning the influence of lactic fermentation on chemical and physical changes in fruiting bodies of edible fungi are also presented.

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Effects of glycerol (Gly) (3–7% w/w) and sorbitol (Sor) (4–8% w/w) concentration, pH (7.0, 9.0, 11.0) and heating (90C, 20 min) of film‐forming solutions (FFS) on the tensile strength (σmax), elongation at break (εb), elastic modulus (EM) and puncture strength (PS) of pea protein isolate (PPI) films were investigated in this study. The films plasticized with Sor exhibited significantly higher σmax, EM, PS and lower εb, in comparison with Gly‐plasticized films. Incorporation of higher Gly and Sor amounts in the films led to decreases in σmax, EM and PS but did not affect εb. An increase of pH value from 7.0 to 11.0 resulted in improved σmax of Gly‐plasticized films, while for films with Sor, this effect was not observed. In turn, εb and PS of the films were significantly increased by alkalization of FFS, regardless of the plasticizer type. Generally, an improvement in mechanical strength of PPI films produced from heated FFS was observed. X‐ray diffraction analyses of Gly‐ and Sor‐plasticized PPI films did not show any differences in their internal structure. Practical Applications Edible films may be used as selective barriers to gasses, carriers of antimicrobial agents or agents improving appearance and handling of many different food groups. Most studies suggest their application as edible coatings that may prolong the shelf life of unprocessed plant and animal products. Other possible uses include wraps and separation layers; pouches, bags, food casings, and labels; drug coatings, capsules and microcapsules; paper coatings. The Sor‐plasticized PPI films can be promising materials for the applications, e.g., in the fields of fruit and vegetables quality preservation. Because of Sor recrystallization, these films are not suitable for low‐water activity food, especially if stored for a long duration at ambient conditions.

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In this study 6 species of wild edible mushrooms were evaluated in terms of their total phenolic content and antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl radical and ferric reducing antioxidant power assay methods. The mushrooms, namely Armillaria mellea, Cantharellus cibarius, Lactarius deliciosus, Leccinum aurantiacum, Suillus luteus, and Boletus badius, were dried using both freeze drying and convection drying at 50°C. The amounts of phenolic compounds varied from 3.0 ± 0.1 to 12.8 ± 0.4 mg gallic acid equivalents/g dry weight (for water extracts) and from 2.4 ± 0.1 to 11 ± 0.5 mg gallic acid equivalents/g dry weight (for ethanolic extracts). The species that presented the highest antioxidant potential were B. badius and S. luteus. The impact of hot-air drying on the antioxidant activity of water and ethanolic extracts was evaluated. We demonstrated that hot-air drying may have either a negative or positive influence on phenolics and antioxidant activity, depending on the mushroom species. However, a negative effect was more frequent.

Tomczyńska-Mleko M., Kamysz E., Sikorska E., Puchalski C., Mleko S., Ozimek L., Kowaluk G., Gustaw W., Wesołowska-Trojanowska M. (2014): Changes of secondary structure and surface tension of whey protein isolate dispersions upon pH and temperature. Czech J. Food Sci., 32: 82-89.The secondary structure of proteins in unheated and heated whey protein isolate dispersions and the surface tension of the solutions were investigated at different pH. Heating protein solutions at 80°C results in an increase of unordered structure. Nevertheless, the difference between the contents of unordered structure in the unheated and heated samples increases with increasing pH of the solution. At low protein concentrations the surface tension decreased with increasing protein concentration to about 5 mg/ml. For the heated solution, a similar trend was observed in the decrease in the surface tension with increasing concentrations of protein. In both cases, the curves depicting the surface tension as a function of protein concentration could be fitted to the exponential function with a negative exponent, but with the heated solutions lower values of surface tension were observed. Studies on the surface tension of whey protein isolate solutions prove that the unfolding of whey proteins, revealed by changes in the secondary structure, causes a decrease in the surface tension.

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