Antanas Šarkinas

Antimicrobial activity of commercial samples of thyme and marjoram oils

Abstract Commercial samples of thyme and marjoram oils were analyzed by capillary GC and coupled GC/MS. The antimicrobial activity of each oil was assessed against 10 different bacteria and eight strains of yeasts. p-Cymene (25.2%), thymol (31.4%) and carvacrol (3.8%) were important compounds in the oil of thyme, while limonene (17.3%), linalool (15.5%), terpinen-4-ol (7.3%), α-terpineol (13.0%) and linalyl acetate (14.1%) were major constituents in marjoram oil. Thyme oil possessed remarkable antimicrobial activity against the tested microorganisms, while marjoram oil demonstrated a lower antimicrobial activity. The antimicrobial activity of oils was higher against yeasts than bacteria.

Phytochemical composition, antioxidant and antimicrobial properties of raspberry fruit, pulp, and marc extracts

In this study, the phytochemical composition (total phenolics, total anthocyanins and ellagitannins) and antimicrobial properties of raspberry fruit, pulp, and marc extracts obtained with 80% methanol and 80% acetone from different plant cultivars were assessed. The extracts were also subjected to screening for their possible antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) assay. The content of total phenolics in berry pulp extracts varied from 20.4 to 35.5, in whole berry extracts from 43.6 to 83.1 and in berry marc extracts from 93.9 to 163.8 mg/g (dry weight of extract). The content of ellagitannins was higher by 63–80% in raspberry marc extracts than in pulp extracts. Raspberry fruit, pulp and marc extracts isolated with aqueous acetone possessed stronger antimicrobial activity than the corresponding extracts isolated with aqueous methanol. The highest inhibitory effect against the investigated Gram-positive bacteria and yeast strains was shown by the extracts isolated from raspberry marc and containing the highest concentrations of total phenolics and ellagitannins.

Influence of lactic acid bacteria–fermented Helianthus tuberosus L. and Lupinus luteus on quality of milk products

ABSTRACT In order to improve the nutritional value and quality of milk products, Helianthus tuberosus L. (HT) and Lupinus luteus (LL) fermented with lactic acid bacteria (LAB) (Pediococcus pentosaceus KTU05-9, P. acidilactici KTU05-7 and Lactobacillus sakei KTU05-6) were used, and the quality parameters (physicochemical, microbiological and sensory) of new fermented milk products were evaluated for the first time ever. Chemical analysis of fermented milk products showed a positive effect of the edible plants. The safety profile and nutritional value were higher in milk-LL products compared with fermented milk-HT products. Fermented milk-HT products were more acceptable because of higher taste pleasure, lower smoothness and external taste compared to fermented milk-LL products. The results clearly indicated that HT rich in inulin and LL rich in proteins can be used with selected LAB to improve the nutritional value and increase the assortment of fermented milk products.

Inactivation of some pathogenic bacteria and phytoviruses by ultrasonic treatment

High intensity ultrasound is becoming important and more widely used in the food industry for microorganisms decontamination. This sterilization technique has been evaluated to improve food safety and to replace common processing with chemical additive compounds. The efficiency of a horn-type power ultrasound treatment (300 W and 600 W, 28 kHz, 10-30 min) on Listeria monocytogenes, Bacillus cereus, Escherichia coli, Salmonella typhimurium bacteria suspensions and phytoviruses was examined in this study. The results of this study showed that ultrasonic treatment can be used to eliminate vegetative cells of gram-positive and gram-negative bacteria from 1.59 to 3.4 log in bacterial suspensions and some phytoviruses in fruits.