Development and optimisation of a synbiotic low‐lactose cow milk beverage via enzymatic hydrolysis using commercial β‐galactosidase preparations

Background and Scope Lactose intolerance (LI) affects approximately 65–70% of the global adult population, yet comparative data on the performance of commercially available β‐galactosidase (β‐gal) preparations under standardised conditions remain limited. This study developed an innovative functional low‐lactose cow milk beverage by evaluating four commercial β‐gal preparations Lacta‐Free ( Aspergillus oryzae ), Maxi‐Lact‐2000 ( Kluyveromyces lactis ), HA‐Lactase‐2100 ( K. lactis ) and NOLA‐Fit‐2800 ( Kluyveromyces fragilis ) at concentrations of 0.1, 0.15 and 0.2% (w/v), systematically optimising enzyme concentration, incubation temperature (10–70°C), hydrolysis time (1–6 h), pH (4.0–7.5), starter culture ratios and fermentation conditions using one‐way ANOVA and Duncan's multiple range test ( P ≤ 0.05). Key Findings and Conclusions Lactose was reduced from 4.71 ± 0.13% to 0.16 ± 0.01% (96.50% hydrolysis). NOLA‐Fit‐2800 achieved the highest hydrolysis rate (94 ± 3%) in the shortest time (2.5 ± 0.1 h) at 0.2%, pH 6.0, and 45°C, confirming it as the most efficient preparation for neutral milk processing. Lacta‐Free (fungal) performed optimally at pH 5.5, while Maxi‐Lact and HA‐Lactase (yeast‐derived) were most effective at pH 6.5. The optimal starter culture ratio of L. lactis : L. cremoris:L. diacetylactis at 2:2:1, fermented at 30 ± 2°C for 8 ± 0.1 h with a 5% (v/v) inoculum and Bifidobacterium bifidum BGN4 supplementation, yielded the highest viable cell count [(1.73 ± 0.05) × 10 9 cfu/g] and conferred synbiotic functionality to the final product. Significance and Novelty This study provides the first systematic side‐by‐side comparison of four commercial β‐gal preparations under identical standardised conditions in the same milk substrate, delivering a validated, industrially applicable process framework to produce functional synbiotic low‐lactose dairy beverages. The findings offer actionable guidance for matching enzyme source to dairy application pH and for designing LAB starter systems that maximise probiotic viability in low‐lactose matrices.