Effects of Lactobacillus spp. on the phytochemical composition of juices from two varieties of Citrus sinensis L. Osbeck: ‘Tarocco’ and ‘Washington navel’

This study aimed to evaluate the effects of fermentation with lactic acid bacteria (LAB) on organic acids, ascorbic acid, phenolic compounds, anthocyanins, and carotenoids of sweet orange (Citrus sinensis) juices. Juices from ‘Tarocco’ and ‘Washington navel’ oranges were fermented at 30 °C for 48 h with L. plantarum, L. rhamnosus, L. paracasei, and L. brevis without supplementation. The juice from ‘Washington navel’ resulted the best medium to grow LAB, especially L. brevis (1.98 ± 0.36 log CFU mL−1 at 48 h). Malic acid was thoroughly converted into lactic acid. Ascorbic acid increased in ‘Tarocco’ juice, peaking to 295 ± 25.3 g L−1 when fermented by L. brevis. The effects of LAB on phenolic compounds were matrix-specific, e.g., L. rhamnosus increased the levels of phenolics in ‘Washington navel’ juice (36.8 ± 1.51 mg L−1; p < 0.05), whereas, it reduced phenolics in ‘Tarocco’ juice (18.8 ± 0.7 mg L−1; p < 0.05). In ‘Tarocco’ juice L. brevis and L. paracasei degraded about 26% of the initial anthocyanin contents, and brought down their levels to 4.93 ± 0.10 and 4.57 ± 0.14 mg L−1, respectively. The juice from ‘Washington navel’ resulted the most suitable to be fermented by Lactobacillus spp