ORIGINAL PAPER Carbohydrate metabolic conversions to lactic acid and volatile derivatives, as influenced by Lactobacillus plantarum ATCC 8014 and Lactobacillus casei ATCC 393 efficiency during in vitro and sourdough fermentation Adriana Paucean • Dan-Cristian Vodnar • Sonia-Ancuta Socaci • Carmen Socaciu Received: 3 October 2012 / Accepted: 1 June 2013 / Published online: 21 June 2013 Ó Springer-Verlag Berlin Heidelberg 2013 Abstract The use of sourdough returned to be popular due to its beneficial nutritional, sensorial properties and physical features. In this study, two types of experiments aimed to evaluate comparatively the efficiency of two Lactobacillus (Lb.) strains, Lactobacillus plantarum ATCC 8014 and Lactobacilus casei ATCC 393, to metabolize different carbohydrates (glucose, fructose, maltose and sucrose) in vitro and to compare their efficiency, combined with/without Saccharomyces cerevisiae on sourdough fer- mentation. Their efficiency was monitored by cellular growth dynamics, pH values and metabolite production (lactic and acetic acid, volatile derivatives) determined by HPLC and GC–MS analysis. Lb. plantarum ATCC 8014 was, generally, more efficient than Lb. casei for carbohy- drate consumption in vitro and release of lactic acid. Unexpected, Lb. casei was able to produce trehalose in vitro, especially when glucose and sucrose were added in media. During sourdough fermentation, Lb. plantarum had a superior growth dynamic and a dominant nonaerobic fermentation, opposite to Lb. casei. By the addition of yeast to lactobacilli after a short-time lactic fermentation, a combined nonaerobic and aerobic fermentation was noticed, reflected by a more complex mixture of volatile derivatives. In vitro, both Lb. strains produced seven vol- atile compounds (carbonyl derivatives), but during sour- dough fermentation, especially after yeast addition, a complex mixture of alcohols, carbonyl derivatives and acetate esters were determined. Lb. strains (especially Lb. plantarum) determined a moderate volatiles production dominated by alcohols, while addition of yeast to Lb. intensified the volatiles’ production and increase the alco- hols proportion against carbonyl derivatives. Keywords Lactobacillus Á Carbohydrates metabolism Á Sourdough Á Lactic acid Á Volatiles Introduction The bread leavening with sourdough is one of the oldest biotechnological processes known in food production. Nowadays, sourdough bread production contributes to cultural and geographical identity of many countries [1], especially in the context of increased consumers’ prefer- ences for natural food products, without chemical addi- tives. The ‘‘renaissance’’ of sourdough use for bread making is motivated by its positive contribution on the dough machinability, on its nutritional and organoleptic properties and prolongation of bread shelf-life [1–3]. Therefore, the use of sourdough can be a ‘‘refreshed tool’’ in the modern baking technology [4]. During the last decade, the biochemistry and physiology of sourdough lactic acid bacteria have received extensive attention [5] and improved the understanding and the con- trol of the sourdough preparation and optimization of bread leavening. The knowledge of the biochemical process and parameters which can influence it (pH, titratable acidity, lactic and acetic acid production and ratios) of lactic acid bacteria plays an important role which may affect the performance of different microorganisms and release of specific volatiles during sourdough fermentation [4, 6–8]. The availability of soluble carbohydrates for metaboli- zation by microbiota represents the essential elements A. Paucean Á D.-C. Vodnar Á S.-A. Socaci Á C. Socaciu (&) Department of Food Science and Technology, Faculty of Food Science and Technology, University of Agricultural Sciences and Veterinary Medicine, 3-5 Ma ˘na ˘s ¸tur str., 400372 Cluj-Napoca, Romania e-mail: csocaciudac@gmail.com; carmen.socaciu@usamvcluj.ro 123 Eur Food Res Technol (2013) 237:679–689 DOI 10.1007/s00217-013-2042-6