Comparison of lactic acid bacteria diversity during the fermentation of Tarhana produced at home and on a commercial scale

In this study, lactic acid bacteria diversity during the fermentation of homemade and commercially prepared Tarhana, a traditional fermented cereal food from Anatolia, was determined and compared. The isolates collected from Tarhana dough were differentiated according to their (GTG)5 profiles and then identified using 16S rDNA and pheS gene sequences. The variation of lactic acid bacteria during fermentation was also screened using PCR-DGGE. Commercially prepared Tarhana dough was fermented with higher Lactobacillus spp. diversity than homemade Tarhana dough. Lactobacillus casei, L. alimentarius, L. fabifermentas, and L. paralimentarius were identified differently from the fermentation of commercially prepared Tarhana dough. PCR-DGGE analysis revealed that L. plantarum was the main strain for homemade Tarhana, whereas L. brevis and L. alimentarius were observed in commercially prepared Tarhana dough fermentation. In conclusion, L. plantarum, L. brevis and L. alimentarius can be useful as a potential starter culture for the industrial production of Tarhana. © 2017, The Korean Society of Food Science and Technology and Springer Science+Business Media Dordrecht

Microbial diversity of traditional kefir grains and their role on kefir aroma

Kefir grains consist of rich bacterial and fungal microflora responsible for the production of this traditional fermented milk beverage with unique flavour properties. Here, a pyrosequencing approach was applied for the identification of microbial flora of four kefir grains collected from different regions of Turkey and the volatile compounds in kefir samples produced with these grains were determined. Lactobacillus kefiranofaciens presented in all grains at important levels and Enterobacter, Acinetobacter, Enterococcus and Pseudomonas spp. were observed in traditional kefir grains. The fungal microflora of kefir grains was dominated by yeast species and Dipodascaceae family was dominant and Saccharomyces cerevisiae presented in all grains. Other yeast species belonging to Kazachstania, Candida, Issatchenkia and Rhodotorula species were also detected in kefir grains. Volatile compounds of kefir samples were also diverse related to the microbial diversity of kefir grains. This study revealed the rich microflora of Turkish kefir grains and their interactions with the aromatic properties of kefir. © 201

Determination of antagonistic starter cultures for pickle and olive fermentation processes

In the present study, the main purpose was the selection of antagonistic starter cultures for pickle and olive fermentation processes. The chemical and microbiological properties of fermented 70 pickle and 16 olive samples collected from the province of the west part of Turkey were analysed. Subsequently, lactic acid bacteria strains producing bacteriocinlike metabolites were isolated and identified. From 86 samples, 16 isolates were chosen, depending on their partial antimicrobial activity against at least one selected indicator. 13 out of this 16 isolates were identified as Lactobacillus plantarum whereas 3 of them proved to be Lactobacillus pentosus. Moreover, all the relevant isolates were found to be potent acid producers. All these results obviously suggest that the isolated Lactobacillus plantarum 9 and 25 were appropriate for them to be proposed as starter cultures in fermented pickle and olive production

Diversity and Stability of Yeast Species During the Fermentation of Tarhana

Tarhana is a traditional cereal-based fermented food produced with a mixture of yoghurt and flour. The main microbiota in the fermentation of tarhana is yeast, together with lactic acid bacteria. In this study, the yeast microbiota of home-made tarhana (HMT) and plant-type tarhana (PTT) dough samples was evaluated and compared during fermentation. Culture-dependent LSU and ITS-5.8S rDNA sequence analysis of yeast isolates collected during the tarhana dough fermentation clarified 45 selected isolates representing different clusters. These yeast isolates displayed high homologywith species Pichia kudriavzevii (11), Candida glabrata (11), Candida humilis (10), Saccharomyces cerevisiae (7), Kluyveromyces marxianus (4), Kazachstania servazzi (1), and Kazachstania unispora (1). Additionally, both culture-dependent and PCR-Denaturated Gradient Gel Electrophoresis (PCR-DGGE) analyses showed that S. cerevisiae, P. kudriavzevii and K. marxianus were abundant in the fermentation of HMT dough samples whereas P. kudriavzevii, C. humilis, and C. glabrata dominated the PTT dough samples. It was concluded that tarhana fermentation was accomplished with the presence of a wide variety of yeast species that mainly included P. kudriavzevii in both HMT and PTT dough samples. © Taylor & Francis Group, LLC

The effect of fermentation time on the volatile aromatic profile of tarhana dough

Tarhana is a traditional food produced by fermentation of a dough prepared by mixing wheat flour, yoghurt, tomato, paprika, onion and mint. The fermentation of mixture of natural products gives the tarhana an aromatized desired food characteristic. Therefore, we aimed to determine the effects of fermentation time at home and commercial scale on the aromatic volatile profile of tarhana. In this respect, nine different tarhana dough samples were prepared at home and commercial scale and analysed for volatile and organic acid composition during fermentation which were then evaluated by principal component analysis. In all dough samples, the lactic, succinic and acetic acids were the most produced organic acids while the amounts of ketones decreased, and the alcohols, in particular the esters, increased within fermentation. Particularly, ethyl-lactate and ethyl-acetate increased significantly as well as ethyl-caprylate, ethyl-capronate and ethyl-hexanote responsible for fruity and flower flavour were also accumulated. Tarhana doughs were clustered in two main groups after five days of fermentation with principal component analysis and these clusters remained stable until the end of fermentation. As a conclusion, fermentation time determines the desirable tarhana by ensuring the formation of aromatic volatiles particularly esters. It is necessary to ferment tarhana for at least five days in order to obtain typical aromatic properties. © The Author(s) 2018

Effects of different fruits and storage periods on microbiological qualities of fruit-flavored yogurt produced in Turkey

Comparative microbiological analyses of fruit-flavored yogurt, plain yogurt, and plain yogurt with 8% sugar were conducted in this research. The fruit-flavored yogurts were produced from evaporated cow's milk (19.75% dry matter) containing 16% jam prepared with an equal weight of sugar and fruit (sour cherry, orange, strawberry, or banana). The total plate count, lactic acid and coliform bacteria, and yeast and mold counts were determined in yogurt samples stored for 1, 3, 5, 7, 9, and 13 days. In conclusion, it is suggested that these types of yogurt should not be stored longer than 7 days, because when a carryover culture is used for yogurt production, most likely yeast contamination will occur. Otherwise, pure starter culture should be utilized in yogurt production

Influence of growth conditions on the nisin production of bioengineered Lactococcus lactis strains

Nisin production of three bioengineered strains, (LAC338, LAC339 and LAC340) with immunity (nisFEG) and/or regulation (nisRK) genes of nisin biosynthesis on plasmids in the Lactococcus lactis LL27 nisin producer, was evaluated under pH-controlled and pH-uncontrolled batch fermentations. Optimization studies showed that fructose and yeast extract yielded the highest nisin activity. The strains LAC338, LAC339, and LAC340 produced 24, 45, and 44% more nisin, respectively, than wild-type L. lactis LL27 after 12-h incubation. However, sharp decreases in the yield of nisin were observed at the late phase of fermentation with LAC339 and LL27 in contrast to LAC340 and LAC338 strains for which the high level of nisin could be maintained longer. Obviously, increasing the copy number of the regulation genes together with immunity genes in the nisin producers retarded the loss of nisin in the late phase of the fermentation. © 2008 Society for Industrial Microbiology

The effect of lactic acid bacteria and yeast usage on aroma development during tarhana fermentation

The aim of this study was to select starter cultures by showing correlation between the volatiles and the starter cultures used during fermentation with the goal of producing a standard and desirable tarhana. This traditional fermented cereal product is produced with fermentation of a dough prepared by mixing wheat flour, yoghurt, some vegetables and spices. To understand the relationship between aroma development and certain starter cultures through both statistical and sensorial approaches, 11 tarhana dough samples were prepared using three lactic acid bacteria (Lactobacillus farciminis PFC83, Lactobacillus casei PFC90, Lactobacillus alimentarius PFC91) or two yeast (Pichia kudriavzevii PFC12, Candida humilis PFC138) strains, as mono- or co-culture. Ester and alcohol volatiles accumulated during fermentation in the tarhana dough samples with starter, triggered by the use of starter cultures. Additionally, it was noted that lactic, succinic and acetic acids were the most prevalent organic acids to be produced in the dough samples during fermentation, and a partial least squares regression analysis showed that L. alimentarius PFC91 and P. kudriavzevii PFC126 were correlated with the accumulation of esters and these organic acids. Moreover, a sensory analysis showed that tarhana dough samples prepared using the L. alimentarius PFC91 and P. kudriavzevii PFC126 strains obtained the most acceptable scores. In conclusion, this study showed a strong correlation between aroma development in tarhana and starter usage in which L. alimentarius PFC91 is co-cultured with P. kudriavzevii PFC126, contributing to the accumulation of the volatile aromatic compounds and organic acids that are responsible for desirable aromatic tarhana. © 2018 Elsevier Lt

Immobilization of nisin producer Lactococcus lactis strains to chitin with surface-displayed chitin-binding domain

In this study, nisin producer Lactococcus lactis strains displaying cell surface chitin-binding domain (ChBD) and capable of immobilizing to chitin flakes were constructed. To obtain ChBD-based cell immobilization, Usp45 signal sequence with ChBD of chitinase A1 enzyme from Bacillus circulans was fused with different lengths of PrtP (153, 344, and 800 aa) or AcmA (242 aa) anchors derived from L. lactis. According to the whole cell ELISA analysis, ChBD was successfully expressed on the surface of L. lactis cells. Scanning electron microscope observations supported the conclusion of the binding analysis that L. lactis cells expressing the ChBD with long PrtP anchor (800 aa) did bind to chitin surfaces more efficiently than cells with the other ChBD anchors. The attained binding affinity of nisin producers for chitin flakes retained them in the fermentation during medium changes and enabled storage for sequential productions. Initial nisin production was stably maintained with many cycles. These results demonstrate that an efficient immobilization of L. lactis cells to chitin is possible for industrial scale repeated cycle or continuous nisin fermentation. © 2013 Springer-Verlag Berlin Heidelberg