A monoclonal antibody against florfenicol amine (FFA) was produced, and a competitive enzyme-linked immunosorbent assay (ELISA) was developed for detecting florfenicol (FF) and FFA in eggs. This proposed method exhibited the 50% inhibiting concentrations (IC 50 ) of 0.120 ng/mL for FF and 0.118 ng/mL for FFA under the optimization of experimental parameters. At the fortified levels of 0.4, 0.8, 2.4, and 30.0 μg/kg, the inter-assay recoveries of the target compounds ranged from 78.3 to 103.2%, and the intra-assay recoveries ranged from 81.5 to 104.1%, respectively. The coefficients of variation were all below 12%. Results for the determination of spiked samples by this ELISA showed a good relationship with the high-performance liquid chromatography (HPLC) technique. This newly developed method confirmed to be rapid, user-friendly, and sensitivity for simultaneous detecting FF and FFA in eggs.

ACE inhibitory and antioxidant peptides from goat milk fermented by Lactiplantibacillus plantarum L60 and Lacticaseibacillus rhamnosus LR22 with Alcalase were optimized through Box–Behnken Design. The effects of enzyme addition, fermentation time, and temperature on DPPH free radical scavenging rate and ACE inhibition rate were studied. The optimum conditions are to add 0.15% enzyme and ferment at 37°C for 12 h, contributing to DPPH free radical scavenging rate of 75.17% and ACE inhibition rate of 84.15%. Compared with the control, it increased by 16.87% and 22.74%, respectively. The bioactive peptides below 3 KDa were obtained by ultrafiltration and identified by liquid chromatography–tandem mass spectrometry (LC–MS/MS). The results demonstrated that both exist three identical peptides: FFDDK, NMAHIPR, SCQDQPTTLAR. There are eight identical peptides in goat milk fermented by two probiotics. This study will contribute to the production of functional fermented dairy products with high ACE inhibitory and antioxidant properties. Practical applications ACE inhibitory and antioxidant peptides have the functions of relieving elevated blood pressure and scavenging free radicals in the body, respectively. In this study, the process of Alcalase‐assisted two probiotics in fermentation was optimized, and ACE inhibition and DPPH free radical scavenging rate are significantly improved. There were three same peptides in five goat milk containing bioactive peptides and they mainly derived from whey protein and casein of goat milk, which indicates the enzymes produced by different probiotics have the same restriction sites.

Angiotensin convening enzyme (ACE) inhibitory peptides can inhibit ACE effectively, which is crucial to regulating blood pressure. Many studies on the production of ACE‐inhibitory peptides by probiotics, but few works have been carried out on Directed‐Vat‐Set (DVS) starter producing ACE‐inhibitory peptides. In the study, The DVS starter producing ACE‐inhibitory peptides were optimized using Lactiplantibacillus plantarum L69 (L69) and starter with Lactobacillus bulgaricus and Streptococcus thermophilus (Starter LS) through the single factor and the Box–Behnken design. The optimum conditions were: Addition of DVS starter is 0.20%, which is composed of Lactiplantibacillus plantarum powder and starter in the ratio of 1:1, cultivation time of 4.5 hr, fermentation temperature 42°C, and the response value were pH of 4.63, optical density (OD) of 0.759, ACE‐inhibition activity of 87.20% in fermented milk. The accelerated storage test demonstrated that the inactivation rate constant of the DVS starter was k−18 = 4.24 × 10−3 at −18°C, indicating good stability. Practical applications ACE‐inhibitory peptides have a significant antihypertensive effect and are safe without toxic side effects compared with ordinary antihypertensive drugs. In this study, Single‐factor and Box–Behnken design were used to optimize the conditions of producing ACE‐inhibitory peptides from DVS starter and the acceleration test was used to evaluate its stability. The fermentation time of DVS starter is shorter and the storage property is better. This study provided technical support for the development of DVS starter for functional dairy products.