Influence of miracle fruit (Synsepalum dulcificum) extract and microencapsulated Lactococcus lactis Gh1 on the antioxidant activity and probiotic viability of functional yogurt
2020
H. Wasoh | N. F. A. Zani | A. Ariff | M. Halim | N. F. Fazilah
Nowadays, functional food market is dominated by dairy-based probiotic products, mainly yogurt. The nutritional values of yogurt can be further enhanced by the inclusion of miracle fruit (Synsepalum dulcificum) and potential probiotic Lactococcus lactis Gh1. The present work investigated the anti-oxidative capacity and survivability of probiotic strains of six yogurts fortified with S. dulcificum pulp extract and encapsulated L. lactis Gh1 (in alginate-starch coating agent via extrusion technique). The flavonoid contents (TFC) were not significantly different between yogurts, whereas the phenolic contents (TPC) showed an increasing trend throughout the storage. Among the yogurts, the one supplemented with both S. dulcificum and encapsulated L. lactis Gh1 showed the highest TFC (1.18 µg QE/mL) and TPC (15.382 μg GAE/mL). The antioxidant assay (DPPH) showed a gradual increase on the first 7 d, but decreased afterward. In comparison, yogurts fortified with S. dulcificum demonstrated higher antioxidant activity (± 80% DPPH inhibition) than the plain yogurts (± 50% DPPH inhibition). The viability of starter cultures (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) drastically increased during the first week (log 8 ~ 10 CFU/mL) especially for yogurts containing free cell L. lactis, but subsequently decreased ( log 6 ~ 8 CFU/mL). The viability of L. lactis Gh1 in yogurts maintained at high count (log 9.43 and 9.04 CFU/mL) throughout 21 d when it was being encapsulated. In general, the fortification of S. dulcificum extract with microencapsulated L. lactis Gh1 had greatly enhanced the quality and potential benefits of the functional yogurts.
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