Influence Of Fermentation Temperature Research Articles

Valorisation of sweet whey by fermentation with mixed yoghurt starter cultures with focus on galactooligosaccharide synthesis

Sweet whey was fermented with yoghurt starter cultures (YO-MIX 101 containing Lactobacillus acidophilus, Streptococcus thermophilus, and Bifidobacterium lactis and YO-MIX 532 containing Lactobacillus delbrueckii subsp. bulgaricus and S. thermophilus) as well as enzyme extracts thereof to synthesise galactooligosaccharides from lactose. The influence of fermentation temperature and initial lactose concentration was studied. The highest yield in sweet whey (34.2% including disaccharide GOS, 25.4% excluding disaccharide GOS) was obtained with the YO-MIX 532 culture at 50 °C and 100 g L−1 initial lactose. With YO-MIX 101, yields were considerably lower, but transgalactosylation was favoured in sweet whey compared with buffer (23.4% versus 8.5% total GOS at 100 g L−1 initial lactose). Of the isolated strains derived from the mixed cultures, only Lactobacillus bulgaricus and both strains of S. thermophilus showed notable GOS synthesis. Up-scaling to a stirred tank reactor system yielded 26.3% total GOS within 24 h of fermentation.

The use of active bakery ingredients in bakery products of functional purpose

The paper describes the possibility of changing of yeast to natural sourdoughs of spontaneous fermentation in bakery products formulations with using of ‘BackNatur’ and ‘O-tenic’ active bakery ingredients. The influence of fermentation temperature and time on the quality of liquid sourdoughs is described, and the content of microorganisms in dried and liquid sourdoughs is shown. There were developed the formulations of bakery products based on the sourdoughs with using of demineralized dried whey, fine mechanochemically treated eggshell powder and infrared-dried carrot powder. All samples were evaluated on their sensory, physico-chemical and microbiological characteristics. The consumption of the developed bakery products satisfies from 10 to 15% of daily requirement for people in β-carotene, dietary fiber, calcium and proteins. The developed bakery products can be recommended as functional bakery products for dietary and gerontological nutrition.

The new insight into the influence of fermentation temperature on quality and bioactivities of black tea

This study aimed to figure out the optimum fermentation temperature by analyzing the major chemical constituents of black tea and its antioxidant activities, inhibitory activities against α-amylase, α-glucosidase and glucose uptake. Sensory evaluation revealed 28°C-fermented black tea showed best sensory quality with highest scores for aroma (6.5) and taste (29.8). With increasing fermentation temperature, polyphenols, polysaccharides, (−)-epigallocatechin, (+)-catechin, theaflavins and thearubigins decreased significantly, while amino acids, soluble sugars and volatiles increased when temperature increased up to 31 °C. Furthermore, black tea fermented at 28 °C showed strongest DPPH radical scavenging ability, anti-lipid peroxidation and inhibitory effect on α-glucosidase activity with IC50 value of 17.72 μg/mL, 1.49 mg/mL and 21.69 μg/mL respectively. While 25°C-fermented black tea showed highest inhibition rate of glucose uptake in Caco-2 cells. The results demonstrate that appropriately lowering fermentation temperature could improve both sensory quality and bioactivity of black tea.

Anaerobic digestion of sludge filtrate assisted by symbionts of short chain fatty acid-oxidation syntrophs and exoelectrogens: Process performance, methane yield and microbial community

Sludge filtrate is a kind of special organic wastewater generated from hydrothermally pretreated sewage sludge. The efficient treatment of sludge filtrate can promote the development of sludge recycling technology. Herein, the anaerobic baffled reactor (ABR) assisted by symbionts of short chain fatty acid-oxidation syntrophs (SFAS) and exoelectrogens was applied to treat the sludge filtrate. The influence of fermentation temperature and promotion of methanogenesis via symbionts were focused. The results showed that the COD removal efficiency and methane yield of the ABR system assisted by symbionts at 35 °C (R3) were 11.7% and 11.0% higher than the one at 55 °C (R2), respectively. And the COD removal efficiency and methane yield of the R2 system were 9.1% and 12.9% higher than the traditional ABR system at 55 °C (R1), respectively. Large abundances of exoelectrogens such as Thermincola and Geobacter were found in the R2 and R3 systems, respectively. Moreover, ample Syntrophobacter, Syntrophomonas and Methanobacterium were detected in both R2 and R3 systems. The present research revealed the importance of SFAS, exoelectrogens and hydrogenotrophic methanogens for the improvement of methanogenesis. Besides, the mesophilic condition is conducive to enhancing the methanogenesis rate of sludge filtrate.

The Role of Saccharomyces cerevisiae Yeast and Lactic Acid Bacteria in the Formation of 2-Propanol from Acetone during Fermentation of Rye Mashes Obtained Using Thermal-Pressure Method of Starch Liberation.

This study set out to assess the acetone content in rye sweet mashes prepared using the thermal-pressure method of starch liberation, and to investigate the formation of 2-propanol during the fermentation process. In the first set of experiments, we evaluated the correlation between the color and the content of acetone and furfural in industrially produced sweet mashes (n = 37). The L * value was negatively correlated with the content of both acetone and furfural, while chromatic parameters a * and b * and the yellowness index (YI) had strong positive correlations with acetone (r > 0.9) and furfural (r > 0.8 for a * and r > 0.9 for b * and YI). In the second set of experiments, we assessed the concentration of acetone and 2-propanol in distillery rye mashes, fermented by S. cerevisiae yeast and lactic acid bacteria. The influence of fermentation temperature on the formation of 2-propanol was also evaluated. The presence of 2-propanol in the post-fermentation media was confirmed, while a decrease in acetone content was observed. Fermentation temperature (27 °C or 35 °C) was found to have a significant effect on the concentration of 2-propanol in trials inoculated with lactic bacteria. The content of 2-propanol was more than 11 times higher in trials fermented at the higher temperature. In the case of yeast-fermented mashes, the temperature did not affect 2-propanol content. The acetone in the sweet mash was assumed to be a precursor of 2-propanol, which was found in the fermented mashes.

Influence of Fermentation Temperature, Yeast Strain, and Grape Juice on the Aroma Chemistry and Sensory Profile of Sauvignon Blanc Wines.

Sauvignon blanc wine, balanced by herbaceous and tropical aromas, is fermented at low temperatures (10-15 °C). Anecdotal accounts from winemakers suggest that cold fermentations produce and retain more "fruity" aroma compounds; nonetheless, studies have not confirmed why low temperatures are optimal for Sauvignon blanc. Thirty-two aroma compounds were quantitated from two Marlborough Sauvignon blanc juices fermented at 12.5 and 25 °C, using Saccharomyces cerevisiae strains EC1118, L-1528, M2, and X5. Fourteen compounds were responsible for driving differences in aroma chemistry. The 12.5 °C-fermented wines had lower 3-mercaptohexan-1-ol (3MH) and higher alcohols but increased fruity acetate esters. However, a sensory panel did not find a significant difference between fruitiness in 75% of wine pairs based on fermentation temperature, in spite of chemical differences. For wine pairs with significant differences (25%), the 25 °C-fermented wines were fruitier than the 12.5 °C-fermented wines, with high fruitiness associated with 3MH. We propose that the benefits of low fermentation temperatures are not derived from increased fruitiness but a better balance between fruitiness and greenness. Even so, since 75% of wines showed no significant difference, higher fermentation temperatures could be utilized without detriment, lowering costs for the wine industry.

Variation of bioactive compounds content in fermented cabbage: influence of fermentation temperature

The aim of this study was to analyze the effect of different fermentation temperature on bioactive compounds content of cabbage heads (Brassica oleracea var. capitata). Fermentation process was carried out at the temperature intervals 16-18°C, 18-20°C and 20-22°C for 40 days. Dry weight, soluble dry weight, pH value, water activity, salt and sugar concentration, total acidity, penetration force, total color change, total phenolic compounds and organic acidswere investigated as the most important quality parameters. The highest content of total phenol compounds, as well as the highest contents of oxalic and acetic acidswas obtained in cabbage and brine sample fermented at 16-18°C. The highest content of lactic acid in the cabbage sample fermented at 20-22°C was obtained. In the case of brine samples, the highest contents of oxalic and lactic acids in samples fermented at 16-18°C were observed, while the highest content of acetic acid in the sample fermented at 20-22°C was obtained. Formic acid in cabbage and brine samples only in samples fermented at 20-22°C was detected.

Influence of fermentation temperature and source of enzymes on enological characteristics of rice wine

Rice wine samples were produced with four sources of enzymes, and with three fermentation temperatures. Key enological variables (including ethanol, the main sugars, glycerol and organic acids) were measured by HPLC at the end of primary fermentation (4 days) and at the end of the postfermentation period (40 days). The results showed that both source of enzymes and temperature had significant effects on the main flavour compounds. Ethanol varied initially, but its final concentration showed a weak dependence on the treatments. Faster starch hydrolysis led to higher initial sugar concentrations, but lower final sugar and higher final glycerol concentrations. Production of organic acids, lactic acid and acetic acid, in particular, depended on the fermentation temperature. The results provide insights into the rice wine fermentation process as affected by different enzymes and fermentation temperatures. Copyright © 2014 The Institute of Brewing & Distilling

The Technological Research of Diosgenin Extraction by Natural Fermentation Method

In order to optimize the best condition of extracting diosgenin in natural fermentation section of natural fermentation acid hydrolysis to explore the influence of fermentation temperature, fermentation time and adding yeast when extracting diosgenin. First set up comparing four fermentation time (t) and five fermentation temperature (T), using reversed-phase high performance liquid chromatography (RP-HPLC) to measure the content of diosgenin, it draws the conclusion that the optimum fermentation time is 48h and the best fermentation temperature is 30°C by natural fermentation; Second compare the yield of adding yeast with the best condition, the results shows that the extraction efficiency with yeast is higher than that of natural fermentation, but the value added is not very large, and it has already achieved good results under the optimal conditions of natural fermentation, so in order to save money, it is not recommended to add yeast.

Cultivating conditions effects on kefiran production by the mixed culture of lactic acid bacteria imbedded within kefir grains

The influence of fermentation temperature, agitation rate, and additions of carbon sources, nitrogen sources, vitamins and minerals on production of kefiran by kefir grains lactic acid bacteria was studied in a series of experiments. The main aim of the work was to increase the exopolysaccharide (EPS) production where customised milk was used as fermentation medium. It was proved that the controlling of culturing conditions and the modifying of fermentation medium conditions (i.e., carbon, nitrogen, mineral sources and vitamins) can dramatically enhance the production of the EPS. The temperature and agitation rate were critical for kefiran production during the 24h cultivation of grains; our optimised conditions being 25°C and 80rpm, respectively. In addition, when optimising the effects of additional nutrition, it was found that 5% (w/v) lactose, 0.1% (w/v) thiamine, and 0.1% (w/v) FeCl3 led to the maximal production of EPS. The results indicate that nutrients can be utilised to improve the production of EPS and that good kefir grains growth does not appear to be a determining factor for a high production yield of EPS.

Characterisation of the exopolysaccharide kefiran produced by lactic acid bacteria entrapped within natural kefir grains

The main goal of this work was to characterise and quantify the exopolysaccharide kefiran and to discover an effective procedure for its isolation from kefir grains, originating from the Caucasian Mountains. Capillary electrophoresis was used for the characterisation and quantification of the d-glucose and d-galactose in our samples at a mass ratio of 1:0.7. The effect of fermentation time on growth of kefir grains and the content of kefiran within the grains were determined. The pH profiles were monitored dynamically. In addition, the influence of fermentation temperature on kefir grains mass concentration (γKG) and the content of kefiran within the grains (wKEF/KG) were studied. The highest values for both were obtained at 30 °C.

Influence of fermentation temperature and autolysis on ACE-inhibitory activity and peptide profiles of milk fermented by selected strains of Lactobacillus helveticus and Lactococcus lactis

Bovine milk was fermented with single strains of Lc. lactis or Lb. helveticus at three temperatures around the optimum for each species. Fermentation was stopped at pH 4.6 and 4.3/4.0, and the products were stored at 5 °C for 1 and 7 days. The extent of lysis was examined by release of X-prolyldipeptidyl aminopeptidase activity, and the angiotensin-I-converting enzyme- (ACE-) inhibitory activity and peptide profiles of the products were determined. Fermentation temperature significantly influenced the bacterial growth, extent of lysis, and ACE-inhibitory activity. ACE-inhibitory activity was high at all temperatures, and slightly higher at the optimal growth temperature, whereas the extent of lysis was highest at a suboptimal growth temperature. Peptide profiles were marginally affected by temperature and cell lysis. The major peptides were identified, including a number of known ACE-inhibitory peptides. Our results suggest that the cell wall proteinase was the primary catalyst in release of ACE-inhibitory peptides.

Influence of fermentation temperature on the content of fatty acids in low energy milk-based kombucha products

The aim of this study was to investigate the influence of fermentation temperature on the fatty acids content in low energy milk-based products obtained by kombucha inoculums with herbal teas. In this investigation low energy milk-based kombucha products were produced from milk with 0.8% milk fat using 10% (v/v) kombucha inoculums cultivated on winter savory, peppermint, stinging nettle and wild thyme. The process of fermentation was conducted at two temperatures: 40?C and 43?C. Fermentation was stopped after the pH value of 4.5 was reached. Duration of the fermentation process was shorter by applying higher fermentation temperature. Fatty acids content was determined by gas chromatography-mass spectrometry. Predominant fatty acids in all obtained products were saturated fatty acids, first of all the monounsaturated ones. The higher temperature resulted in the formation of lower amount of saturated fatty acids in the obtained milk-based kombucha products.

Biohydrogen production from cattle wastewater by enriched anaerobic mixed consortia: Influence of fermentation temperature and pH

Experiments were conducted to select a natural mixed microflora seed source and investigate the effect of temperature and pH on fermentative hydrogen (H2) production from cattle wastewater by sewage sludge. Sewage sludge was shown to have higher cumulative H2 production than other inoculum collected from cow dung compost, chicken manure compost, and river sludge. Experimental results show that H2 production from cattle wastewater was significantly affected by both pH and temperature of the culture. The maximum H2 yield was obtained at pH 5.5. H2 yield and the ratio of butyrate/acetate (Bu/Ac) followed a similar production trend, suggesting that butyrate formation might favor H2 production. The optimal temperature for H2 production from cattle wastewater was 45 degrees C with peak values of H2 production (368 ml), hydrogen yield of 319 ml H2/g chemical oxygen demand (COD) consumed, and butyrate/acetate ratio of 1.43. Presence of ethanol and propionic acid indicated decreased hydrogen production; their concentrations were also affected by pH and temperature. A modified Gompertz model adequately described H2 production and bacterial growth.

Influence of wine fermentation temperature on the synthesis of yeast-derived volatile aroma compounds

The yeast Saccharomyces cerevisiae synthesises a variety of volatile aroma compounds during wine fermentation. In this study, the influence of fermentation temperature on (1) the production of yeast-derived aroma compounds and (2) the expression of genes involved in aroma compounds' metabolism (ADH1, PDC1, BAT1, BAT2, LEU2, ILV2, ATF1, ATF2, EHT1 and IAH1) was assessed, during the fermentation of a defined must at 15 and 28 degrees C. Higher concentrations of compounds related to fresh and fruity aromas were found at 15 degrees C, while higher concentrations of flowery related aroma compounds were found at 28 degrees C. The formation rates of volatile aroma compounds varied according to growth stage. In addition, linear correlations between the increases in concentration of higher alcohol and their corresponding acetates were obtained. Genes presented different expression profiles at both temperatures, except ILV2, and those involved in common pathways were co-expressed (ADH1, PDC1 and BAT2; and ATF1, EHT1 and IAH1). These results demonstrate that the fermentation temperature plays an important role in the wine final aroma profile, and is therefore an important control parameter to fine-tune wine quality during winemaking.

Optimization of sourdough process for improved sensory profile and texture of wheat bread

The aim of the study was to determine optimum sourdough process conditions for improved flavour and texture of wheat bread. The influence of process conditions and the starter culture on the characteristics of wheat sourdough bread was established by using response surface methodology. Influence of fermentation temperature (16–32 °C), ash content of flour (0.6–1.8 g/100 g), and fermentation time (6–20 h) were considered as independent factors and their effects were studied in sourdough bread fermented with Lactobacillus plantarum, Lactobacillus brevis, Saccharomyces cerevisiae or with a combination of yeast and lactic acid bacteria. Intensity of sensory attributes, specific volume and bread hardness were considered as the main responses. Ash content of flour and fermentation time were the main factors determining the intensity of sensory attributes. The possibility to enhance intensity of overall flavour, aftertaste and roasted flavour without excessive pungent flavour and without reduced fresh flavour in wheat bread containing 20 g sourdough/100 g of wheat dough was demonstrated by choosing e.g. Lb. brevis for a starter and by utilization of high ash content of flour, long fermentation time and reduced temperature. Bread specific volume was improved 0.2–0.5 ml/g and hardness was reduced (after 4 days of storage) up to 260 g by using low ash content of flour and by optimizing fermentation time according to the microbial strain. Lactic acid fermentation had more profound influence on both desired and undesired flavour attributes, as well as textural features of bread in comparison with yeast fermentation.

Influence and Interactions of Processing Conditions and Starter Culture on Formation of Acids, Volatile Compounds, and Amino Acids in Wheat Sourdoughs

ABSTRACTThe aim of this work was to study the influence of process parameters and the starter culture on the characteristics of wheat sourdough by using response surface methodology. Influence of fermentation temperature (16–32°C), ash content of flour (0.6–1.8%), and fermentation time (6–20 hr) were considered as independent factors and their effects were studied in sourdough fermented with Lactobacillus plantarum, L. brevis, Saccharomyces cerevisiae, or with a combination of yeast and lactic acid bacteria. Formation of acidity, free amino acids, and volatile compounds were considered the main responses. A possibility to enhance formation of potential flavor compounds and precursors without excessive acidity formation in wheat sourdoughs was established. The total amount of amino acids increased by 25–50%, depending on the strain and fermentation conditions. The total amount of volatile compounds increased seven‐ to 100‐fold, depending on the strain and fermentation conditions. Sourdough started with S. cerevisiae was an effective way to optimize the amount of volatile compounds without excessive acidity formation in appropriate processing conditions. Ash content of flour and fermentation time were the most significant factors to modify metabolic activity of wheat sourdoughs. Frequent interactions between the studied factors were observed on the formation of acidity, amino acids, and volatile compounds with most of the strains studied. Possibility to improve current industrial fermentation processes and control flavor attributes of breads by using optimized sourdough was established.

Effects of fermentation temperature on the strain population of Saccharomyces cerevisiae

The influence of fermentation temperature (from 15 to 35 °C) on a mixed strain population was studied. Mitochondrial DNA analysis was used to differentiate Saccharomyces cerevisiae strains and the frequency of each strain during the alcoholic fermentation was determined. The chemical analyses of resulting wines were carried out. The temperature determined how Saccharomyces strains developed and how effectively they fermented. Some strains performed better at high temperatures and others at low temperatures. The maximal population size was similar at all temperatures. At low temperatures, however, it was reached later though it remained constant throughout the alcoholic fermentation. On the other hand, viable cells decreased at high temperatures, especially at 35 °C. Obviously, the composition of the wines changed as the temperature of fermentation changed. At low temperatures, alcohol yield was higher. Secondary metabolites to alcoholic fermentation increased as the temperature increased. Glycerol levels were directly affected by temperature.

Influence of fermentation temperature on semi-continuous acetification for wine vinegar production

This paper describes semi-continuous acetic acid fermentations for wine vinegar production performed isothermally and using temperature gradients in order to determine the influence of temperature on this industrial biotransformation. Acetifications were conduced in 6- to 100-l reactors. Overall process productivity improved about 15–20% using a temperature gradient. An initial temperature of 32 °C was employed until the product concentration reached 90–95 g/l/h. Thereafter, the temperature was gradually reduced to 30 °C until the end of the production cycle. Under these operating conditions, the 100-l acetator yielded an overall productivity of 1.84±0.03 g/l/h, a maximum acetification rate of 2.10±0.02 g/l/h, a 94.3±0.4% process yield, and a final acetic acid concentration of 116.0±0.9 g/l.

Influence of Fermentation Temperature on Composition and Sensory Properties of Semillon and Shiraz Wines

Crushed Semillon grapes were pressed after 24 hr pomace contact and fermented at one of four temperatures (15, 20, 25, or 30°C) to assess the effect on the chemical composition and sensory properties of the wines. An additional treatment (15°C fermentation without prior pomace contact) was included to assess the impact of pomace contact. Shiraz grapes were fermented according to one of three temperature regimes (15°C; 20°C for 3 days followed by 30°C; 30°C for 3 days followed by 20°C), with and without a prefermentation cold soak. An additional treatment involved a cold soak, 20°C fermentation temperature for 3 days followed by 30°C, plus a 3-day postfermentation extended maceration. Increasing fermentation temperature in Semillon tended to increase titratable acidity (TA) and absorbance (A₄₂₀) slightly. The 20 and 30°C temperatures resulted in the highest ethanol content. Pomace contact reduced wine TA and increased pH and A₄₂₀. Within the two 15°C treatments, tasters found pomace contact wines had less earthy aroma and herbaceous flavor. Among the pomace contact treatments, 15°C fermentations resulted in less yellow color and herbaceous aroma, and fruitier aroma than 30°C fermentations. Increasing fermentation temperature, use of cold soak, and extended maceration tended to reduce Shiraz wine TA and increased pH and anthocyanins. Use of cold soak increased color (15°C only) and black currant flavor, reduced herbaceous flavor, but reduced black currant aroma. Extended maceration enhanced wine color and body but increased herbaceous aroma. Increasing fermentation temperature from 15 to 30°C increased wine color, reduced herbaceous flavor, increased black currant flavor, but increased perceived acidity. These results suggest that Semillon wines should be produced through the use of prefermentation pomace contact and cool fermentation temperatures, whereas Shiraz wines would benefit from higher fermentation temperatures, use of cold soak, and extended postfermentation maceration.