Algae are common all over the Earth. Due to their rich chemical composition and content of bioactive substances they have been used in many fields of industry. Their gelling, thickening and stabilizing properties have led to the development of such products as agar, alginate and carrageenan. Moreover, algae are used in the food industry as food supplements and an addition to functional food. Algae are also added to meat products, such as pasty, steaks, frankfurters and sausages, as well as to fish, fish products, and oils, to improve their quality. Cereal-based products, such as pasta, flour and bread, are another group of products enriched with algae. Due to their properties algae may also be used for construction of fermented functional food. Fermented products containing algae are, most of all, dairy products, such as cheese, cream, milk deserts, yoghurt, cottage cheese, and processed cheese. Combination of fermented products offering a high content of lactic acid bacteria with algae possessing biologically active metabolites of natural origin allows not only to compose products with a high content of nutrients, but also to create a brand new segment of fermented food.

The aim of this study was to evaluate the effect of the algae Chlorella vulgaris on the growth, acidifying activity, proportion of lactic acid isomers, and enzymatic profile of Lactobacillus brevis (ŁOCK 0944, ŁOCK 0980, ŁOCK 0992, and MG451814) isolated from vegetable silages. The results indicated that adding algae at concentrations of 0.1% (w/v) and 1.5% (w/v) to the Lactobacillus spp. growth medium accelerated the growth of bacteria and thus shortened their phase of logarithmic growth. The acidifying activity of the tested Lactobacillus brevis increased with an increased concentration of algae. Lactobacillus spp. cultured in the presence of Chlorella vulgaris showed higher production of l-lactic acid and lower d-lactic acid production. Moreover, the addition of algae changed the enzymatic activity of lactic acid bacteria; for instance, Lactobacillus brevis ŁOCK 0980 demonstrated more enzymatic activity of valine arylamidase, α-galactosidase, and α-glucosidase. Combining Lactobacillus brevis with the algae Chlorella vulgaris allows for the creation of innovative, functional products which confer favorable properties to the final product and open new horizons for the food industry.

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Alternaria spp. fungi, characterized by a high tolerance to unfavorable environmental conditions, are one of the threats for foods of plant origin. The increasing incidence of diseases caused by a demanding lifestyle, and a higher social awareness of the role of a diet in maintaining health and good condition, results in the dynamically growing demand for natural protective measures that would be safe for consumers. Ellagitannins, i.e. a group of bio-active polyphenols, may constitute an alternative for chemical preservatives. Studies demonstrated that the raspberry (Rubus idaeus L.) ellagitannin formula limited the growth of Alternaria alternata 0409. The minimal inhibitory concentration (MIC) was determined (0.156 mg/ml), along with the minimal fungicidal concentration (MFC) (0.312 mg/ml). The fungistatic (FA) activity and the ratio of linear growth (T) were also determined for the ellagitannin formula. A strong antimycotic activity of ellagitannins was demonstrated at the formula level of 0.1 mg/ml. Unfortunately, the activity was not maintained over time and after 9 days it was only 16.0%. For the ellagitannin formula, concentrations of 0.312 mg/ml (MFC) and 0.5 mg/ml (below the MFC value), a complete arrest of growth of Alternaria alternata 0409 was observed, and it was maintained for 9 days. The antimycotic activity of the ellagitannin formula was also confirmed in food environment, with cottage cheese and cherry tomatoes used as the matrix. Results confirmed that ellagitannins from raspberry (Rubus idaeus L.) could be successfully used as a natural food preservative.

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