Alfalfa sprout flour: A promising ingredient to improve probiotic survival and antioxidant activity in mint-flavored stirred yogurt

Abstract

This study examined the impact of alfalfa sprout flour (ASF) on the pH, titratable acidity (TA), syneresis, water-holding capacity (WHC), color attributes, antioxidant potential, survival of Lactobacillus acidophilus LA-5, and sensory properties of mint-flavored stirred yogurt over 24 days of cold storage. Four probiotic yogurt batches were prepared, namely plain probiotic yogurt (PPY), mint-flavored probiotic yogurt (MFPY), and MFPY with 0.5 and 1 % w/w of ASF (MFPY-ASF-0.5 %, and MFPY-ASF-1 %). Yogurt with added ASF exhibited the highest increase in TA (18.80–24.40 %) and a decrease in pH (0.18). L. acidophilus maintained the highest survival rate (7.3–7.43 Log CFU/g) in MFPY-ASF-1 % yogurt between days 8 to 24 of storage, exceeding the minimum count recommended for the therapeutic effects of probiotics. PPY and MFPY demonstrated significantly lower WHC and higher syneresis values compared to MFPY-ASF-0.5 % and MFPY-ASF-1 % (P < 0.05). The addition of mint and ASF remarkably decreased lightness (L*) and increased yellowness (b*) and greenness (-a*) values of samples compared to PPY. All flavored samples exhibited a gradual decrease in b* and -a* values, alongside an increase in L* values, during storage. ASF-enriched yogurts showed high total phenol content, total flavonoid content, and antioxidant activity. Although an increase in ASF levels resulted in a reduction in consumer preferences for odor and flavor, all samples received satisfactory overall acceptability scores (3.05–4.30) at the end of storage. In conclusion, the inclusion of ASF at the 1 % level presents a promising opportunity for producing value-added yogurt with enhanced probiotic survival, antioxidant activity, and favorable technological properties.

Keywords

• Alfalfa sprout
• Antioxidant activity
• Lactobacillus acidophilus
• Probiotic survival
• Stirred yogurt