Vasiliauskienė, Gabrielė

Strawberries are widely valued for their nutritional properties and high content of bioactive compounds; however, they are also highly susceptible to microbial contamination during fruit ripening. This study aimed to evaluate the distribution of micromycetes and yeasts, as well as antioxidant activity and total phenolic content, in strawberries of two cultivars, Aprica and Malvina, at different ripening stages. Strawberry fruits were collected at three ripening stages (I – early, II – intermediate, III – fully ripe). Micromycetes were isolated using malt extract agar and identified based on morphological characteristics. Antioxidant activity was determined using DPPH, ABTS, and FRAP assays, while total phenolic content was measured using the Folin–Ciocalteu method. Three micromycete genera (Mucor mucedo, Penicillium expansum, Rhizopus stolonifer) and two yeast genera (Rhodotorula and Candida) were identified in the analysed samples. A greater diversity of micromycetes was observed in the Aprica cultivar, especially at the fully ripe stage, where yeasts more frequently colonized Malvina fruits. The antioxidant activity increased with fruit ripening in both cultivars. The highest DPPH and ABTS radical scavenging activity was detected in fully ripe Malvina fruits (109.02 and 133.88 μmol TE/g, respectively). The total phenolic content also increased during ripening, reaching 25.64 mg GAE/g in Aprica and 25.60 mg GAE/g in Malvina fruits. These results demonstrate that strawberry cultivar and ripening stage significantly influence micromycete occurrence and antioxidant properties of the fruits.

The anatomy and physiology of the digestive system of a newborn calf and a mature ruminant are distinct. The digestive tract of a newborn calf is considered sterile, but colonization by a variety of microorganisms commences within 20 minutes and intensifies with each day of life [1]. The complex microbiota of the ruminant gastrointestinal tract affects not only the digestion of feed, but also the overall immune system, nutrient absorption, and general metabolism [2]. The present study aimed to investigate the influence of calves’ age on the count of rumen bacteria and protozoa. The eight-month study included 30 clinically healthy Lithuanian Black-and-White Holsteinized calves, aged from three to eight months. They were housed in compliance with the Calf Welfare Requirements. The calves were divided into three groups based on their age: group 1-G included 3-month-old calves, group 2-G included 3.5-month-old calves, and group 3-G included 8-month-old calves. All calves were provided with a balanced diet and had access to water ad libitum. Samples of rumen fluid were obtained from the calves in all groups using a probe. The count of Protozoa was determined in a Fuchs-Rosenthal counting chamber (Blaubrand, Wertheim, Germany) using an Olympus U-TV1X-2 microscope (Tokyo, Japan). The genera of protozoa were identified according to the method of Dehority [3]. Bacterial counts were determined in accordance with the methodologies outlined in the relevant standards: the Aerobic and Facultative Anaerobic Bacteria count according to LST ISO 4833-1:2013; the Lactic Acid Bacteria – LST ISO 15214:2009; the Enterobacteriaceae – LST ISO 21528-2:2009. In 8-month-old calves, the total protozoa count was on average 18.6% higher if compared with those at 3 and 3.5 months of age. Among all age groups, Entodinium was the most dominant genus found in the rumen fluid. The population of aerobic and facultative anaerobic bacteria was on average 45.1% higher in 8-month-old calves than in the groups of younger animals. Lactic acid bacteria and anterobacteriaceae were first detected at 3.5 months of age, with their levels being 46.8% lower and 10.6% higher, respectively, compared to 8-month-old calves. The total count of Protozoa was found to be influenced by calf age to the extent of 68.4%. Furthermore, the count of five protozoa genera Diplodinium, Enoploplastron, Entodinium, Isotricha and Opisthotrichum were found to be influenced by calf age to the extent of 52.14%. Furthermore, the number of aerobic and facultative anaerobic bacteria was found to be influenced by calf age to the extent of 21.6%. Finally, the number of lactic acid bacteria was found to be influenced by calf age to the extent of 42.3%.

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