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The study aimed to evaluate the chemical composition (total phenol, flavonoid, and tannin content and the antioxidant activity) of 11 apple (Malus domestica) cultivars in fresh apples and their processing by-products — apple pomace and its water extract. In addition, the proportion of chemical compounds and antioxidant activity in fresh apples and pomace transferred to the resulting water extract was calculated. Three different season’s cultivars (autumn–winter, winter and late winter) were selected in the research, and significant differences between chemical parameters within groups were found. Cultivars ‘Zarja Alatau’, ‘Belorusskoje Malinovoje’, ‘Sinap Orlovskij’ and ‘Antej’ are characterised by a higher content of determined compounds in fresh apples, pomace and po-mace water extract. The results showed that the water extract in relation to fresh apples and apple pomace still contains an appropriate amount of total phenols, flavonoids and tannins in the range 2.5–9.6%. These results indicated that apple pomace water extracts could be recommended for use in food as well as in the pharmaceutical industry.

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Silver nanoparticles (AgNPs) biosynthesized using aqueous medical plant extracts as reducing and capping agents show multiple applicability for bacterial problems. The aim of this study was to expand the boundaries on AgNPs using a novel, low-toxicity, and cost-effective alternative and green approach to the biosynthesis of metallic NPs using Calendula officinalis (Calendula) and Hyssopus officinalis (Hyssopus) aqueous extracts. The formation of AgNPs was confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) techniques. The effectiveness of biosynthesized AgNPs in quenching free radicals and inhibiting the growth of Gram-positive and Gram-negative microorganisms was supported by in vitro antioxidant activity assay methods and using the Kirby–Bauer disk diffusion susceptibility test, respectively. The elucidated antimicrobial and antioxidative activities of medical plant extracts were compared with data from the engineered biosynthetic AgNPs. The antimicrobial effect of engineered AgNPs against selected test cultures was found to be substantially stronger than for plant extracts used for their synthesis. The analysis of AgNPs by TEM revealed the presence of spherical-shaped nano-objects. The size distribution of AgNPs was found to be plant-type-dependent. The smaller AgNPs were obtained with Hyssopus extract (with a size range of 16.8 ± 5.8 nm compared to 35.7 ± 4.8 nm from Calendula AgNPs). The AgNPs’ presumably inherited biological functions of Hyssopus and Calendula medical plants can provide a platform to combat pathogenic bacteria in the era of multi-drug resistance.

Candied quince is one of the most popular processing products of Japanese quince (Chaenomeles japonica) in Latvia. During the storage of dehydrated fruit, the colour turns darker, thus negatively influence the overall quality and consumers' acceptability of the product. The aim of the present study was to evaluate the effectiveness of different anti-browning agents in combination with fruit blanching and soaking as a type of pre-treatment to preserve the colour of candied quince during 8-months storage. The fruit were harvested at various maturity stage (i.e. unripe, semi ripe and ripe) with the following pre-treatment using three anti-browning agents (L-cysteine, NATRApHASE Ò ABAF and Natureseal Ò AS1). Hunter L (whiteness/darkness), a (redness/greenness) and b (yellowness/blueness) values were used to measure change in colour. These values were also used for calculation of the total colour change (DE*). Considering blanching and soaking as a type of treatment. Best results were obtained with blanching treatment. L* values decreased significantly after dehydration, showing that the samples became darker, during the further 8-months storage, L* values increased, positively influencing the colour of the tested fruit. The data obtained using the Analytic Hierarchy Process Analysis revealed that 0.3% L-cysteine was the best for effective prevention of colour change during long-term storage among the tested agents.

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