Effect of the Freeze-Dried Mullein Flower Extract (Verbascum nigrum L.) Addition on Oxidative Stability and Antioxidant Activity of Selected Cold-Pressed Oils

The effect of ultrasound-assisted maceration of selected cold-pressed oils with lyophilized mullein flowers (Verbascum thapsus L.) on their oxidative stability and chemical composition

The study aimed to evaluate the effect of ultrasound maceration of cold-pressed oils with freeze-dried mullein flowers (Verbascum thapsus L.) on their oxidative stability and chemical composition. After the maceration process, oils' were subjected to their oxidative stability (80-120 °C) and their chemical composition, Moreover, oils kinetics parameters were calculated. Maceration enhanced the oxidative stability of the tested oils, particularly linseed and chia oils, from 9.66 to 13.44 h and 4.95 to 8.10 h at 90 °C, respectively. The levels of phenolic compounds and phenolic acids significantly increased, especially in rapeseed oil, from 148.02 to 387.43 (mg GAE 100 g -1) and from 84.16 to 2620.93 (μg 100 g-1), respectively. The oils were also enriched with flavonoids and carotenoids. The oils exhibited higher acid and peroxide value, but lower p-anisidine value after maceration process. The fatty acid composition and the content of sterols and tocochromanols in the oils changed only slightly.

Quality assessment of yellow mealworm (Tenebrio molitor L.) powders processed by pulsed electric field and convective drying

Edible insects offer opportunities for food production, as they are an interesting source of many nutrients. In this study, the effect of pulsed electric field (PEF) and convective drying on the chemical composition with emphasizing the fat properties as well as physical, techno-functional, and thermal properties of yellow mealworm powders was investigated. The chemical composition of the yellow mealworm powders differed by PEF. When PEF was applied at 20 and 40 kJ/kg, the moisture, ash, and protein content were significantly lower, while the fat extraction yield significantly increased compared to the control sample. Furthermore, the fat extracted from these samples was characterized by a higher proportion of saturated and monounsaturated fatty acids as well as a higher thrombogenicity index, which is not beneficial from a nutritional point of view. After treatment with PEF at 5 kJ/kg, the powder was the lightest, redness and yellowness. Moreover, the highest hygroscopicity, water activity, and water and oil binding capacity for this powder were determined. The results revealed that yellow mealworm powders are a good source of macronutrients and exhibit beneficial techno-functional properties, nevertheless, the drawback is their high cohesiveness (1.27-1.44), which can be difficult to apply under industrial conditions.

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.

Special Issue: Bioactive Compounds, Nutritional Quality, and Oxidative Stability of Edible Oils and By-Products of Their Extraction

Edible oils (refined, virgin, and cold-pressed oils) are one of the most important components of the daily human diet and have a considerable influence on the proper functioning of our body [...].