Scale up fermentation of Chenopodium formosanum dairy products with process optimization and evaluation of ACE inhibitory peptides and antioxidant activity

In this study, fresh dairy fortified with 7.5 % Chenopodium formosanum was fermented with three lactic acid bacteria (Streptococcus thermophilus BCRC 14085, Lactiplantibacillus plantarum BCRC 11697, Lactobacillus delbrueckii subsp. bulgaricus BCRC 10696) at 107 CFU/mL. A 5 L bioreactor operating at 40 °C, 30 rpm and 21 h achieved 54.81 % inhibition of angiotensin-converting enzyme (ACE). The value remained 53.54 % after scale-up to 50 L. Free phenolics reached 1.76 ± 0.02 mg GAE/g, bound phenolics 1.12 ± 0.05 mg GAE/g and free flavonoids rose by 8.43 % relative to the 5 L batch. ABTS and DPPH radical-scavenging activities increased by 1.56 % and 6.85 %, respectively, whereas phytic acid declined to 4.65 ± 0.42 mg/g. Eleven peptide sequences containing putative ACE-inhibitory fragments were identified by LC-MS/MS and BIOPEP-UWM-assisted screening, among which QAGEAWQEAK was prioritized as a candidate peptide based on in-silico prediction. During 28 day of storage at 4 °C, viable lactic bacteria stayed above 8 Log CFU/mL even though titratable acidity exceeded 1 % after day 21. A sensory panel detected no difference in overall liking between the flavored product and a commercial sugar-free cereal yoghurt. These findings demonstrate a scalable process for producing a C. formosanum fermented dairy beverage with potential to support blood pressure management and deliver antioxidant benefits.