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PRODUCTION D’ACIDE LACTIQUE SUR JUS DE DATTE EN CULTURE PURE ET MIXTE PAR LACTOBACILLUS CASEI ET LACTOCOCCUS LACTIS


NANCIB NABIL*, NANCIB AICHA*, BOUDRANT JOSEPH**
*DEPARTMENT OF MICROBIOLOGY, FACULTY OF SCIENCES, UNIVERSITY FERHAT ABBAS, SETIF, ALGERIA, E-MAIL: NANCIBNABIL@YAHOO.FR **LSGC-CNRS-ENSAIA, BP 172, AVENUE DE LA FORĂŠT DE HAYE, 54505 VANDOEUVRE-LES-NANCY, FRANCE

Issue:

SCSCC6, Volume V, No. 1

Section:

Volume V (2004)

Abstract:

Lactic acid is considered as a very important chemical compound with significant applications in pharmaceuticals, cosmetics and especially in the food industry. New applications, such as degradable plastics made from poly(lactic) acid, have the potential to greatly expand the market for lactic acid, if more economical processes could be developed. Industrial processes for the production of lactic acid typically use sucrose from cane and beet sugar, whey containing lactose and maltose and dextrose from hydrolysed starch. Algeria produces more than 400 different varieties of dates with an annual production of over 300.000 tons. However, about 20 % of the production is lost due to over-ripening and improper handling, processing, and marketing. Dates contain large amounts of reducing sugars, especially glucose, fructose and sucrose at levels of (73 – 83 %) (dry basis). The date also contains protein, lipid, fibre, mineral elements and some vitamins. Thus making date extracts quite suitable as feedstock for fermentation. Complex mixed cultures have also been used in several fermentation processes, e.g. the production of ethanol, aspartic, and succinic acid from glucose and lactic acid from starch. Mixed cultures have not been used yet on an industrial scale, because it is difficult to establish optimum culture conditions for both strains for parameters such as nutrient supply, temperature, oxygen demand, pH, etc. Only a few reports concern the production of lactic acid from starch, non-fat dry milk, and whey permeate by mixed cultures in batch fermentation. Lactic acid production from date juice extract by mixed culture of Lactobacillus casei and Lactococcus lactis cells has not been investigated. In this study, date juice was used as substrate for production of lactic acid by single and mixed culture system containing Lactobacillus casei and Lactocccus lactis. One important parameter in sustaining an economically viable production of lactic acid is the interaction between feedstock and microorganism. The bacteria must be able to convert all the available carbohydrates to lactic acid. All experiments were performed as batch. Lactobacillus casei and Lactococcus lactis were incubated at their optimum temperatures of 30 and 38°C, respectively. A temperature of 30°C was used for co-cultivation. In batch culture, the results have shown that the highest concentration of residual date sugar extract was obtained in fermentation with L. lactis while the lowest concentration was found in fermentation with mixed cultures of L. casei and L. lactis. This coincides with lactic acid production. The highest concentration of lactic acid (60 g/l) was obtained in the mixed culture system while in single culture fermentations of Lactobacillus casei or Lactococcus lactis, the maximum concentration of lactic acid was 53 and 46 g/l, respectively. Our results showed an important aspect of lactic acid production from date juice by single and mixed cultures of Lactobacillus casei and Lactococcus lactis. The mixed culture system gave better results than single cultures regarding lactic acid concentration, and sugar utilization. The date juice extract was an attractive medium for the production of lactic acid by single and mixed culture.

Keywords:

Lactic acid, date juice, Lactobacillus casei, Lactococcus lactis, mixed cultures.

Code [ID]:

CSCC6200405V01S01A0012 [0001033]

Full paper:

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