Blackberry Juice Fermented with Two Consortia of Lactic Acid Bacteria and Isolated Whey: Physicochemical and Antioxidant Properties during Storage

Abstract

Fermenting fruit juices with lactic acid bacteria (LAB) is a sustainable method to enhance fruit harvests and extend shelf life. This study focused on blackberries, rich in antioxidants with proven health benefits. In this research, we examined the effects of fermentation (48 h at 37 °C) at 28 days on whey-supplemented (WH, 1:1) blackberry juice (BJ) inoculated with two LAB mixtures. Consortium 1 (BJWH/C1) included Levilactobacillus brevis, Lactiplantibacillus plantarum, and Pediococcus acidilactici, while consortium 2 (BJWH/C2) comprised Lacticaseibacillus casei and Lacticaseibacillus rhamnosus. All of the strains were previously isolated from aguamiel, pulque, and fermented milk. Throughout fermentation and storage, several parameters were evaluated, including pH, lactic acid production, viscosity, stability, reducing sugars, color, total phenolic content, anthocyanins, and antioxidant capacity. Both consortia showed a significant increase in LAB count (29-38%) after 16 h. Sample BJWH/C2 demonstrated the best kinetic characteristics, with high regression coefficients (R² = 0.97), indicating a strong relationship between lactic acid, pH, and fermentation/storage time. Despite some fluctuations during storage, the minimum LAB count remained at 9.8 log CFU/mL, and lactic acid content increased by 95%, with good storage stability. Notably, sample BJWH/C2 increased the total phenolic content during storage. These findings suggest that adding whey enhances biomass and preserves physicochemical properties during storage.

Keywords: antioxidants; blackberry juice; fermentation; lactic acid bacteria; whey.

Figure 1

Growth of LAB during fermentation at 0, 24 and 48 h. Individual strains: Levilactobacillus brevis (L. b), Lactiplantibacillus plantarum (L. p), Pediococcus acidilactici (P. a), Lacticaseibacillus rhamnosus (L. r), and Lacticaseibacillus casei (L. c) were inoculated and fermented in WH (whey protein) (A), BJ (blackberry juice) (B), and BJWH (blackberry juice + whey protein) (C). WH/C1 (whey protein inoculated with consortium 1: L. b, L. p and P. a), WH/C2 (whey protein inoculated with consortium 2: L. r and L. c), BJ/C1 (blackberry juice with consortium 1), BJ/C2 (blackberry juice with consortium 2), BJWH/C1 and BJWH/C2 (blackberry juice + whey protein with consortium 1 and 2, respectively) (D). Values represent three experiments’ mean ± standard deviation (n = 3). Different capital letters indicate a significant difference (p < 0.05) between the different strains or consortium for each fermentation time. Different lowercase letters indicate a significant difference (p < 0.05) of each strain or consortium between their different fermentation times.

Figure 2

LAB growth during (A) fermentation of 48 h and (B) storage days after 16 h of fermentation of BJWH/C1 and BJWH/C2 (blackberry juice + whey protein with consortium 1 and 2, respectively). The sample contains C1: Levilactobacillus brevis, Lactiplantibacillus plantarum, and Pediococcus acidilactici and C2: Lacticaseibacillus casei and Lacticaseibacillus rhamnosus. Values in each point represent three experiments’ mean ± standard deviation (n = 3). Different black (BJWH/C1) and blue (BJWH/C2) lowercase letters indicate a significant difference (p < 0.05) in different fermentation and storage times.

Figure 3

Lactic acid (A) and pH (B) values across the time of fermentation (16 h) and the time of storage (28 days) in Blackberry juice + whey protein inoculated with consortium 1 of Levilactobacillus brevis, Lactiplantibacillus plantarum, and Pediococcus acidilactici (BJWH/C1), consortium 2 of Lacticaseibacillus casei and Lacticaseibacillus rhamnosus (BJWH/C2) and the negative control without LAB inoculum (BJWH/C-). Values represent three experiments, mean ± standard deviation (n = 3). Different capital letters indicate significant differences (p < 0.05) between the various strains or consortiums for each fermentation and storage time. Different lowercase letters indicate a significant difference (p < 0.05) of each strain or consortium between their different fermentation and storage times.

Figure 4

Non-linear regression analysis lactic acid values across the time of fermentation (16 h) and the time of storage (28 days) in blackberry juice + whey protein inoculated with consortium 1 of Levilactobacillus brevis, Lactiplantibacillus plantarum, and Pediococcus acidilactici (BJWH/C1) (A,B), consortium 2 of Lacticaseibacillus casei and Lacticaseibacillus rhamnosus (BJWH/C2) (C,D).

Figure 5

Non-linear regression analysis pH values across the time of fermentation (16 h) and the time of storage (28 days) in blackberry juice + whey protein inoculated with consortium 1 of Levilactobacillus brevis, Lactiplantibacillus plantarum, and Pediococcus acidilactici (BJWH/C1) (A,B), consortium 2 of Lacticaseibacillus casei and Lacticaseibacillus rhamnosus (BJWH/C2) (C,D).

Figure 6

Content of total phenolic compounds (A), anthocyanins (B), ABTS scavenging (C), and DPPH scavenging (D). Values across the time of fermentation (16 h) and the time of storage (28 days) in Blackberry juice + whey inoculated with consortium 1 of Levilactobacillus brevis, Lactiplantibacillus plantarum, and Pediococcus acidilactici (BJWH/C1), consortium 2 of Lacticaseibacillus casei and Lacticaseibacillus rhamnosus (BJWH/C2) and the negative control without LAB inoculum (BJWH/C-). Values represent three experiments with mean ± standard deviation (n = 3). Different capital letters indicate significant differences (p < 0.05) between the different strains or consortiums for each fermentation and storage time. Different lowercase letters indicate a significant difference (p < 0.05) of each strain or consortium between their different fermentation and storage times.