Development of kefir technology with celery pure
Authors: Tsisaryk O. , Musii L. , Dronyk G. , Drach M. , Slyvka I. 
Published: December 2022

The creation of new types of functional food products is an actual direction of the development of the food industry at the present time. The purpose of the work was to develop the technology, to investigate the properties and quality indicators of kefir using celery puree. Experimental studies of organoleptic, physicochemical and microbiological indicators of kefir were conducted in the laboratory of the department of technology of milk and dairy products. For the production of kefir we used a fermentation culture directly applied by DVS company “CHR Hansen” (Denmark) Kefir-1, which includes Debaryomyces hansenii yeast and meso- and thermophilic lactococci: Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis biovar. diacetylactis, Lactococcus lactis subsp. lactis, Leuconostoc, Streptococcus thermophilus. Stalks of celery were used to prepare puree in laboratory conditions. Stalks celery were washed, cut into small cubes. Chopped celery cubes were placed in a vessel, a small amount of water was added, brought to a boil. After that, the water was drained, and the celery cubes were carefully ground with a blender to a smooth puree-like consistency. At the first stage, kefir recipes were developed using different amounts of celery puree. We produced 3 samples of kefir: sample 1 – use of celery puree in the amount of 20 % to the weight of the normalized mixture; sample 2 – 30 %; sample 3 – 35 %. Kefir was made by the tank method. The cooled milk was sent for normalization. After normalization, the milk mixture was sent for pasteurization at a temperature of (95 ± 1) °C with a holding time of 5 minutes. Fermentation culture Kefir-1 was added to the milk mixture cooled to a temperature of (30 ± 1) ºС. To evenly distribute the culture, mixing was used for 10-15 minutes. The mixture was subjected to fermentation at a temperature of (30 ± 1) ºС. After fermentation, celery puree was added to the milk mixture in the amount of 20, 30 and 35 % to the product weight. The mixture was thoroughly mixed and the product was immediately cooled to a temperature of 8 °C and sent to maturation for 12 hours. Organoleptic, physical and chemical and microbiological indicators were studied in the finished product in accordance with DSTU 4417:2005 “Kefir. Specifications”. The titrated acidity was determined according to GOST 3624-92 “Milk and dairy products. Titrometric methods of determining acidity”. Active acidity was measured using an electronic pH meter “Muttler Toledo MP220”. The total number of lactic acid cultures was determined by parallel inoculation of dilutions of yogurt samples in Petri dishes on Lactobacagar medium followed by incubation in a thermostat at a temperature of (37 ± 1) ºС for 3 days under anaerobic conditions. According to organoleptic parameters, in particular, better appearance and consistency, it is recommended to use celery puree in the amount of 35 % of the product weight in kefir technology. The physical and chemical parameters of the milk-vegetable product after maturation are as follows: titrated acidity 75–80 ºT, active acidity 4.8–4.7 units pH, mass fraction of fat 2.5 %. During storage for 14 days, acidity changed the least in milk-vegetable kefir with celery puree in a sample with 35 % puree, which is caused, in our opinion, by the presence of essential oils in celery puree, which suppress the development of lactic acid microflora. The results of determining the number of viable lactic acid bacteria in kefir during storage at a temperature of (4 ± 2) ºС for 14 days indicate the intensification of the growth of lactic acid bacteria. Their development was more active in the sample using the smallest amount of celery puree.