Effect of Addition of Jelly and Storage Time on the Number of Lactic Acid Bacteria in Yoghurt Processed Products

Abstract

BACKGROUND: Yoghurt is a milk fermentation product that is one of the highly nutritious food materials involving bacteria. Yoghurt is formed from lactic acid bacteria (LAB), namely, Lactobacillus bulgaricus, Lactobacillus acidophilus and Streptococcus thermophilus. The bacteria are beneficial for health because it creates a balance of the intestinal microflora. Moreover, yoghurt has a distinctive freshness, aroma and taste, namely, sour. In the yoghurt fermentation process, LAB needed a substrate for their growth. The content of natural sugar in milk is minimal; therefore, jelly needs to be added, which the microorganism can directly use for its growth. AIM: This study aims to determine the effect of adding jelly with various concentrations and storage time on the number of LAB in processed yoghurt products. METHODS: This research used the measurement method of total LAB with plate count method using completely randomized design factorial pattern 1 × 3 with three repetitions. The factor I is the jelly concentration (0.5%, 0.75% and 1%) and factor II is storage time (7 days, 14 days, 21 days at a temperature of 2–8°C) with data processing using statistical tests, namely, two-way analysis of variance test followed by Duncan’s Multiple Range Test. RESULTS: The results showed significant differences in the storage time of 7 days, 14 days, and 21 days on agar with concentrations of 0.5%, 0.75%, and 1%. The highest LAB amount was on the 7th day with a concentration of 1% with 2.51 × 109. While on the 21st day, with a concentration of 1%, it had the lowest LAB amount of 3.2 × 108. However, the amount of LAB was still above the Indonesian National Standard, namely >107 CFU/mL. CONCLUSION: This study concluded that the highest number of LAB was found in the addition of 1% jelly with a storage time of 7 days with a total LAB yield of 2.51 × 109 CFU/mL. Storage time on day 7, day 14 and day 21 and jelly concentrations of 0.5%, 0.75%, and 1% added to processed yoghurt had a significant effect (p < 0.05) on the total number of LAB (p < 0.05) LAB).