This study aims at an in vitro characterization of the acid and bile tolerance of Lactobacillus fermentum InaCC B1295 (LFB1295) encapsulated with hydrogel cellulose microfibers (CMF) from oil palm empty fruit bunches (OPEFBs). The viability at different storage temperatures was assessed. The experimental design used in this research was an in vitro trial. The microencapsulated probiotic was stored at 25 °C and 4 °C for 28 days. LFB1295 encapsulated with cellulose microfiber hydrogel from OPEFB showed a stable viability of probiotic bacteria at pH 2 and 0.5% (m/v) oxgall. In addition, the microencapsulation maintained the viability at 25 °C and 4 °C at 0, 14, and 28 days. The characterization of the encapsulant CMF-OPEFB showed that the thickness of CMF was in the range of 5–15 μm, and XRD patterns showed that CMF was of the cellulose I type with a crystallinity index of 77.08%. Based on its resistance to hydrogen peroxide, ability to scavenge DPPH radicals, and activity in scavenging hydroxyl radicals, LFB1295 encapsulated with CMF hydrogel of OPEFB exhibits antioxidant properties as good as the scavenging ability of DPPH radicals with IC50 of 36.880, 188.530, and 195.358 µg/mL, respectively, during storage for 0, 14, and 28 days at room and refrigerated temperature. Furthermore, hydroxyl radicals (HR)-scavenging activity showed an increased inhibition along with the increasing concentration of the Fenton reaction and decreasing concentration of cell-free supernatant (CFS) during storage time. In vitro safety tests, including hemolytic activity, biogenic amines, cytolysin, and gelatinase production, showed that the encapsulated LFB1295 was safe to use as a probiotic. The results of the inhibitory activity against hydrogen peroxide LFB1295 show that the higher the concentration of H2O2, the lower the inhibition value during 28 days of storage. Based on the storage temperature, the inhibition of LAB against H2O2 based on different storage temperatures showed a better level of the inhibition at cold temperatures compared to at room temperature.

Lactic acid bacteria is a group of bacteria with proteolytic activities enambling to grow on protein rich substrate such as soymilk. This research was aim to isolate and identify lactic acid bacteria with have proteolytic activity from spontaneous fermented soy milk. Sixteen isolates out of 26 colonies isolated from fermented soymilk are presumed as lactic acid bacteria. Among these 16 isolates, only 3 of them showed proteolytic activity. These three isolates were further identify morphologically and only two isolates identified as Lactic Acid Bacteria, namely R.1.3.2 and R.11.1.2. The ability of these isolates to produce acid and protease were observed. The results showed that isolate R 1.2.3 higher ability in producing protease.

Yusmarini 1) *, Retno Indrati 2) , Tyas Utami 2) dan Yustinus Marsono 2)

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Background Soursop is one type of fruit with high productivity, but its utilization is relatively less than other fruits. This imbalance causes many soursop fruits to be damaged, so it needs to be processed into functional food in the form of probiotic drinks. Making soursop fruit juice probiotic drink utilizes Lactobacillus plantarum 1 RN2-53 as a starter, but the resulting product has an unattractive color. The addition of red dragon fruit peel extract is expected to provide an attractive color and increase the nutritional value and benefits of probiotic drinks. Research purposes The study aimed to obtain the best red dragon fruit peel-extract concentration as a natural dye for soursop probiotic drinks. Method: The sample used was a soursop probiotic drink with the addition of red dragon fruit peel extract using five different concentration levels, namely 5%, 10%, 15%, 20%, and 25%. The Hunter color system method used a colorimeter to conduct the color test. Results and Discussion: Red dragon fruit peel extract with 5%, 10%, 15%, 20%, and 25% significantly affected the microbiological, Physico-chemical, and sensory characteristics of the soursop probiotic drink. Anthocyanin dyes in red dragon fruit peel increase a* value in the color test, the percentage of total titrated acid and total LAB, and decrease the pH value, b* value, and L* value in the color test. Conclusion: The N5 treatment with the addition of 25% (b/b) concentration of red dragon fruit peel extract resulted in a pH value of 3.88, total acid titrated 0.71%, total LAB 9.22 log CFU/ml, color test value L* 24 ,19, color test a* 4.09 and color test b* -2.65.