Une méthode de dosage en ligne du diacétyle et de l'acetaldehyde dans les yaourts, laits fermentes, beurres et margarines

Abstract

~An on-line method for the measurement of diacetyl and acetaldehyde in yoghurt, fermented milk, butter and margarine. A new method for the measurement of diacetyl and acetaldehyde in fats, fermented dairy products and batch-cultures of Lactococcus lactis ssp. lactis bv. diacetylactis is proposed. A gas membrane sensor connected to agas chromatograph is used for direct analysis. At 35 "C, the lowest limits of detectionare 0.005 mg-L:" for diacetyl and 0.01 mgL-I for acetaldehyde. At this temperature, linearity is observed from 0.005 to 50 mg.L:' for diacetyl and from 0.01 to 80 mg-L:' for acetaldehyde. As variations in response were noted when this method was applied to commercial samples containing fats, it is recommended to perform calibration in the tested product or in the fermentation media. In this study, the gas membrane sensor was shown to be a valuable tool for diacetyl and acetaldehyde determination in commercial products and for on-li ne measurement of various volatile compounds during lactic acid bacteria cultures. © InralElsevier, Paris.

A comparison of the physicochemical, microbiological and aromatic composition of Traditional and Industrial Leben in Tunisia

“…The LAB and yeast counts in TL were higher ( P < 0.05) than those in EL and IL. Mesophilic LAB are the main microflora responsible for lactic acid fermentation and aroma development in fermented milks (Stien et al. 1999).…”