The application of the Plackett-Burman design in investigating ACE inhibitory peptide-producing conditions and media for Lactobacillus bulgaricus LB6.

BACKGROUND

The intake of angiotensin converting enzyme (ACE, EC 3.4.15.1) inhibitory peptides from food has become a promising method for treating hypertension. Lactic acid producing bacteria are widely used to produce ACE inhibitors during fermentation.

METHODS

Several factors which promote the production of ACE inhibitory peptides in Lacto- bacillus bulgaricus LB6 (inoculum size, incubation temperature, goat’s milk powder, sterilization time, whey powder, casein hydrolyses and calcium lactate) and media (casein peptone, soybean peptone, glucose, casein, ascorbic acid, Ca(H2PO4)2 and lactose) were investigated to optimize and increase ACE inhibitory activity during the fermentation of goat’s milk by using a Plackett-Burman design, in accordance with previous tests.

RESULTS

The results indicated that incubation temperature, whey powder, calcium lactate, soybean peptone,glucose and casein had significant effects on both ACE inhibition rate and viable counts. In addition, the effects of incubation temperature, whey powder, calcium lactate and glucose were found to increase ACE inhibition rate, while soybean peptone and casein caused it to decrease.

CONCLUSIONS

This investigation of conditions which promote the production of ACE inhibitory peptides and media for LB6 was performed using a Plackett-Burman design. The results indicated that incubation tem- perature, whey powder, calcium lactate, soybean peptone, glucose and casein had a significant impact on the ACE inhibition rate and viable counts of LB6, which provide the basis and reference for further optimization.