Determination of conditions for non-microbial fermentation of garlic (Allium sativum L.) for use in food systems

The aim of the study is to evaluate the effect of non-microbial fermentation conditions (temperature and duration) on the garlic darkening process. Objectives: to determine the effect of temperature and duration of garlic fermentation on the intensity of its darkening, as well as the accumulation of 5-hydroxy-methylfurfural as a key intermediate of the Maillard reaction. The object of the study is common garlic of the Dobrynya variety. To obtain black garlic, the heads were cleaned of the upper several contaminated layers of the husk, placed in a desiccator with water to maintain constant humidity during fermentation and prevent drying of the samples at high fermentation temperatures. The desiccator was placed in a dry-air adjustable thermostat and garlic was fermented at 60; 70; 80 and 90 °C for 12–60 days. The process of garlic darkening during fermentation can be divided into three stages: initiation of the darkening process (the first 3–6 days of fermentation); intensive development of the darkening process (from 6 to 15 days) and completion of the darkening process (within 3–40 days). The appearance of black garlic obtained by fermentation at 60 °C was unsatisfactory, with individual drops of water under the husk, which may lead to microbiological contamination during storage of such a product. Fermentation of garlic at 90 °C resulted in a solid product with a distinct smell and taste of burning. The amount of 5-hydroxymethylfurfural increases in all samples of fermented garlic regardless of temperature, but the reaction rate was higher at higher temperatures. Heating at 80 and 90 °C led to a significant increase in the rate of 5-hydroxymethylfurfural formation and contributed to obtaining a product of a favorable black color with shine, however, the taste characteristics of these samples were less preferable compared to samples fermented at 60 and 70 °C, since they had an unpleasant bitter taste of burnt sugar.