Influence of drying methods on the structure, mechanical and sensory properties of strawberries

Effect of Pulsed Electric Field Technology on the Composition and Bioactive Compounds of Black Soldier Fly Larvae Dried with Convective and Infrared-Convective Methods

In recent years, an increasing interest has been shown in alternative food sources. Many studies are focused on the use of insects. The aim of this study was to investigate the changes in the chemical and thermal properties of black soldier fly larvae influenced by the pulsed electric field (PEF) and convective (CD) or infrared-convective (IR-CD) drying techniques. Examinations of the basic chemical composition, properties of extracted fat (fatty acid composition, acid and peroxide values, and oxidative stability), total polyphenol content, antioxidant activity, allergen content, and thermogravimetric analysis (TGA) were performed. Generally, the results showed that dried black soldier fly larvae are a good source of protein and fat, up to 33% and 44%, respectively. The fat extracted from the dried insects consisted mainly of saturated fatty acids (above 75%), in particular lauric acid (C12:0). A good oxidative stability of the fat was also observed, especially from samples dried with the IR-CD method. The convective drying technique allowed for better preservation of protein content compared to samples dried with the IR-CD method. Nevertheless, samples treated with PEF were characterized by significantly lower protein content. The samples after PEF pretreatment, with an intensity of 20 and 40 kJ/kg and dried with the IR-CD method, were represented by a significantly higher total polyphenol content and antioxidant activity. Furthermore, in most cases, the convectively dried samples were characterized by a higher allergen content, both crustaceans and mollusks. Taking into account all of the investigated properties, it can be stated that the samples without treatment and those that were PEF-treated with an intensity of 40 kJ/kg and dried with the infrared-convective method (IR-CD) were the most rewarding from the nutritional point of view.

Influence of Drying Type of Selected Fermented Vegetables Pomace on the Natural Colorants and Concentration of Lactic Acid Bacteria

Nowadays, foods with probiotic bacteria are valuable and desired, because of their influence on human gut and health. Currently, in the era of zero waste, the food industry is interested in managing its waste. Therefore, the aim of the study was to determine the influence of drying process on the physicochemical properties of fermented vegetable pomace. The work included examining the influence of the lactic acid bacteria (Levilactobacillus brevis, Lactiplantibacillus plantarum, Limosilactobacillus fermentum and its mixture in the ratio 1:1:1) used for vegetable fermentation (beetroot, red pepper, carrot), obtaining pomace from fermented vegetables, and then selection of drying technique using the following methods: convection drying (CD) or freeze-drying (FD) on the physical and chemical properties of pomace. In the obtained pomace and its dried form, dry substance, water activity, color, and active substances such as betalains and carotenoids by spectrophotometric method and also bacteria concentration were evaluated. After fermentation of pomace from the same vegetable, a similar concentration of lactic acid bacteria was found as well as dry substances, color and colorants. Results of physico-chemical properties were related to the used vegetable type. After drying of pomace, it could be seen a high decrease in bacteria and colorant concentration (betalains, carotenoids) independently from drying and vegetable type as well as used starter cultures. The smallest change was observed for spontaneously fermented vegetables compared to those in which the starter culture was used.