Production optimization and properties of carbohydrate-based yogurts utilizing Dioscorea hispida Dennst tubers as raw material

Abstract

Importance of the work: Dairy-based yogurts can trigger lactose intolerance, increasing the demand
for carbohydrate-based alternatives for health reasons.
Objectives: To investigate the potential of Dioscorea hispida Dennst tubers as raw material for
producing carbohydrate-based yogurt.
Materials and Methods: Yogurts were made using D. hispida flour and starch, using Lactobacillus
delbrueckii subsp. bulgaricus (LB) and Streptococcus thermophilus (ST). The production varied the
tuber-to-water ratio, lactic acid bacteria and skim milk. Product quality was determined based on the
pH, titratable acidity, syneresis and viable cell count. The extended fermentation, storage stability,
proximate composition and sensory properties of the products were evaluated.
Results: The optimal flour-based product used a flour-to-water ratio of 1:10, a bacterial mix of LB and
ST and 1% skim milk. The starch-based product used a starch-to-water ratio of 1:8, the same bacterial
mix and 3% skim milk. Extended fermentation showed significant (p < 0.05) variations in titratable
acidity (TA) and viable cell counts for yogurt-like product from flour (YLPF), while yogurt-like
product from starch (YLPS) had differences in the pH and TA. There was a significant difference in
the TA between the two products. Storage at room and cold temperatures (4°C) affected the syneresis,
TA and viable cell count for both products, with room temperature storage producing slightly better
results. Compared to YLPF, YLPS had higher levels of crude protein, lipid, fiber, reducing sugar and
TA. Sensory evaluation revealed that both were inferior to the dairy-based control.
Main finding: D. hispida tubers had potential as a substrate for carbohydrate-based yogurts.
However, further optimization is required to improve the storage stability and sensory qualities.
This study should provide a foundation for developing novel carbohydrate-based products from
underutilized tuber crops.