EFFECT OF POLYPHENOLS FROM APPLE SKIN ON Lactobacillus higardii X1B GROWTH

MARÍA R. ALBERTO; MARÍA C. MANCA DE NADRA

Tucumán, Argentina

Simposio; II Simposio Internacional Bacterias Lácticas; 2006

CERELA

Phenolic compounds have many biological activities with relevance for the human health: anti-inflammatory, antimicrobial, antioxidant and antiallergic properties. Apples, fruits consumed worldwide in different forms i.e. fresh, in juices and cider, present beneficial properties for the human health related to the high content in polyphenols. Lactobacillus hilgardii, food and fermented drinks contaminant lactic acid bacterium, has the capacity to produce toxic compounds for the consumer, like biogenic amines and precursory compounds of the carcinogenic ethyl carbamate. The objective of this work is to analyze the effect of polyphenols from apple skin in the growth of L. hilgardii X1B. Polyphenols present in Royal Gala and Granny Smith apple skin were extracted using three different solvent mixtures: A: acetone:water:acetic acid, B: ethyl acetate:methanol:water and C: ethanol:water. In the different extracts the total phenolic compound content is determined and expressed in milligrams of gallic acid equivalent by gram of skin (mg GAE/g). The studies of the growth are in FT80 medium added with 10% of the extracts A, B and C. The media are inoculate to 7% v/v with a culture DO 0.8 of L. hilgardii and incubated to 30¡ãC during 50 h. As controls the FT80 media with 10% of clarified extracts with activated charcoal were used (Ac, Bc, Cc). The growth is determined espectrofotom¨¦tricamente to 600 nm. Extracts A (3.49 mg GAE/g), B (1.99 mg GAE/g) and C (2.60 mg GAE/g) of Royal Gala variety do not modify the final cell density reached by the bacterium with respect to their clarify controls. Nevertheless the growth rate (¦Ìmax) diminishes 43, 38 and 35% in the presence of the extracts A, B and C, respectively. In the Granny Smith variety the extracts A (6.80 mg GAE/g) and B (5.08 mg GAE/g) decrease 81 and 31% the final cell density with respect to their clarify controls and extract C (3.02 mg GAE/g) does not modify it. The ¦Ìmax diminishes 71, 59 and 29 % in the presence of the extracts A, B and C, respectively. The extract A, of the Granny Smith variety of greater phenolic content shows greater inhibiting effect on the growth of L. hilgardii, affecting both growth parameters. In order to know the mechanism of action of polyphenols present in the extract of the Granny Smith variety, cells of L. hilgardii growth in the FT80 media added with 10% of the extracts A or Ac are taken and transfer to fresh FT80 media without extracts. The growth is measure determining  D.O.600 nm and ufc/ml. Cells of L. hilgardii after 15 and 35 h of contact with polyphenols of the extract A of the Granny Smith variety when transferred to fresh medium reinitiate the process of multiplication independently of the time of contact. The results of DO and ufc/ml indicate the bacteriostatic effect of phenolic compounds of the extract A of the Granny Smith variety.