Abstract:
Incorporation of probiotics such as Lactobacillus rhamnosus GG (LGG) into non-dairy food matrices (fruits and vegetables) has recently been explored but with negative impact on the viability of organisms due to low pH. Provitamin A cassava starch hydrolysate could be a better vehicle in enhancing the viability of LGG, owing to its high glucose content which improves probiotic viability when exposed to low pH. However, there is paucity of information on incorporation of LGG into provitamin A cassava hydrolysates as non-dairy probiotic carrier. This study was designed to evaluate the quality and safety attributes of provitamin A cassava starch hydrolysate as carrier for LGG.
Starches from three provitamin A cassava varieties (IITA-TMS-I011368, IITA-TMS-I070593 and IITA-TMS-I011371) were extracted and hydrolysed using α-amylase and glucoamylase. The hydrolysates were inoculated with free and alginate-encapsulated LGG, and analysed after fermentation (48 h) and during storage (4oC, 90 days). Chemical [residual hydrogen cyanide (HCN) and β-carotene retention], antioxidant [2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity] and microbiological [coliforms, Salmonella spp., Shigella spp. and survival/viability of LGG in Simulated Gastric Juice (SGJ), Simulated Intestinal Juice (SIJ) and hydrolysates] properties were determined. Hydrolysate with the most significant properties was selected and administered to adult Wistar rats (120-150 g). Acute toxicity (n=65 females; 24 h) and sub-acute toxicity (n=40 males; 30 days) studies of hydrolysate were conducted. Signs of acute toxicity were monitored, while blood and organ samples (kidney and liver) were collected on Day 31 for sub-acute toxicity and compared with the control. Data were analysed using descriptive statistics and ANOVA at α0.05.
Residual HCN decreased significantly from 25.06-38.70 to 1.00-1.80 mg/kg in the hydrolysates, making it safe for consumption. β-carotene retention and DPPH assay ranged from 47.37 to 94.44% and from 83.30 to 86.97%,indicating strong antioxidant activity. No coliforms, Salmonella and Shigella were observed for 30 days of storage. Encapsulated LGG had better percentage survival in SGJ (77.36%) and SIJ (31.21%) than free LGG at 6.53% and 1.22%, respectively. Viable counts of LGG in hydrolysates before and after fermentation were 7.32-7.48 and 9.12-9.23 Log CFU/mL (free), and 7.51-7.73 and 9.28-9.32 Log CFU/mL (encapsulated), respectively. Viability of free (91.45%) and encapsulated LGG (94.01%) was maintained after 30 days, but reduced significantly to 35.77 and 57.78%, respectively by the end of 90 days of storage. No sign of toxicity was observed. The IITA-TMS-I011368 hydrolysate groups with free LGG, encapsulated LGG and control had blood urea nitrogen of 1.15, 2.09 and 1.28 g/dL, and albumin:globulin ratios were 1.43, 1.90 and 1.55 respectively. Aspartate aminotransferase, Alanine transaminase and Alkaline phosphatase in IITA-TMS-I011368 hydrolysate groups with highest dose of LGG were 65.00, 54.80 and 39.60 IU/L (free), 72.40, 62.20 and 52.80 IU/L (encapsulated), and 74.40, 62.60 and 49.20 IU/L (control) respectively, indicating no kidney and liver damage.
A high quality, safe and microbiologically stable probiotic carrier with properties that supported the growth of Lactobacillus rhamnosus GG was developed from hydrolysed provitamin A cassava. Encapsulated Lactobacillus rhamnosus GG maintained significant viability in fermentation and storage.
