The Effect of Cold Storage Time and Locust Bean Gum Addition as Stabilizer Agent on Quality of Probiotic Yoghurt Enriched with Sorghum and Moringa Flour

Abstract

Sorghum and moringa are two local commodities with functional properties for food ingredients. Previous research showed that adding sorghum flour (1% (w/v)) and moringa flour (0.03% (w.v)) mixture increased probiotic yoghurt's physicochemical and microbiological quality. However, the quality of the selected yoghurt formula was not evaluated during cold storage (5°C). Moreover, it has not been added with any stabilizer agent. Therefore, this paper aimed to 1) evaluate the physicochemical quality change of sorghum and moringa enriched yoghurt formula with the addition of LBG (locust bean gum) as a stabilizer and 2) evaluate such physicochemical quality during cold storage. In this research, LBG concentration (0%, 0.3%. 0.6%, 0.9% (w/v)) and storage time (0 week, 1 weeks, and 2 weeks) were used as variables. Batches that contain 12% of milk skim were added with 1% (w/v) modified sorghum flour, 0.03% (w/v) moringa flour and locust gum. Then, 5% of LAB (Lactic Acid Bacteria) strains were cultured into the mixture and incubated at 37°C for 18 h. The samples were stored in 5°C refrigerators and analyzed according to the storage time. Physically, pH, water holding capacity, viscosity, and texture profile were measured. Chemically, DPPH antioxidant activity and total phenol were analyzed. Finally, LAB was counted using the TPC (total plate count) method. This research showed that only the cold storage time variable contributed significantly to the physicochemical characteristics of the yoghurt.