Residual Sugar Content Research Articles

Enhancement of nuclease P1 production by Penicillium citrinum YL104 immobilized on activated carbon filter sponge.

The efficiency of current methods for industrial production of the enzyme nuclease P1 is limited. In this study, we sought to improve fermentation methods for the production of nuclease P1. An immobilized fermentation system using an activated carbon filter sponge as a carrier was used for the production of nuclease P1. In an airlift internal loop reactor (ALR), the fermentation performance of three different fermentation modes, including free-cell fermentation, repeated-batch fermentation, and semi-continuous immobilized fermentation, were compared. The fermentation kinetics in the fermentation broth of the three fermentation modes, including dissolved oxygen (DO), pH value, cell concentration, residual sugar concentration, and enzyme activity, were tested. The productivity of semi-continuous immobilized fermentation reached 8.76 U/mL/h, which was 33.3 and 80.2% higher than that of repeated-batch fermentation and free-cell fermentation, respectively. The sugar consumption of free-cell, repeated-batch, and semi-continuous immobilized fermentations was 41.2, 30.8, and 25.9 g/L, respectively. These results showed that immobilized-cell fermentation by using Penicillium citrinum with activated carbon filter sponge in an ALR was advantageous for nuclease P1 production, especially in the semi-continuous immobilized fermentation mode. In spite of the significant improvement in nuclease P1 production in semi-continuous immobilized fermentation mode, the specific activity of nuclease P1 was almost equal among the three fermentation modes.

Trebbiano wine produced by using Saccharomyces cerevisiae strains endowed with β-glucosidase activity

The purpose of this research was to evaluate the ability of four strains of Saccharomyces cerevisiae endowed with β-glucosidase activity to improve the Trebbiano wine aroma profiles and quality. In particular, the strain effects on fermentation kinetics, sugar and acid concentrations, volatile aroma compound profiles, colour, and catechins parameters were evaluated. The four strains of S. cerevisiae were tested in comparison with a commercial strain. The results showed that the four wild strains had high fermentation rates associated with an efficient conversion of grape sugars to alcohol. In addition, each strain imparted specific features to the wine. In fact, significant differences in relation to the inoculated strain were observed mainly in residual sugar content, succinic and tartaric acid concentrations, and volatile aroma compound profiles as esters, higher alcohols, and terpenes. In particular, the products obtained with S. cerevisiae BV12 and BV14 were characterized by lowest residual sugar contents. Moreover, BV14 and AS15 produced the wines with the highest concentrations of succinic and tartaric acids. Also, the wine obtained with the strains AS11 and AS15 showed high concentrations of monoterpenes and particularly linalool and geraniol having a strong sensorial impact. Furthermore, the wine obtained with the strain AS11 showed a minor decrease in colour intensity, probably due to the highest content of total SO2. These results outlined the importance of the strain selection, tailor made based on the wine feature and the wine making process adopted.

표고 액체종균 배양시 배지와 균사체의 양분변화

Jeonbuk National University, Iksan Campus, Bio Food Technology Ma-dong, Iksan 570-752, KoreaABSTRACT: Lentinula edodes liquid spawn growth under explosive aeration (supplying air with tiny bubbles) and soybean mealaddition to liquid culture medium were investigated in terms of mycelial growth and residual free sugar content. The twotreatments were effective for homogeneous culturing of mycelial spawn and for separating colonies during multiplication after anexponential growth period without limiting sustaining nitrogen nutrients. The mycelial growth and carbon dioxide concentrationwere greatest on the 13th day since the inoculation. At 12th day, however, free sugars were almost depleted in the upper part ofthe liquid medium. Total nitrogen content within precipitated mycelia was the highest at the 13th day. Chitin and sucrose contentsin the mycelia were the highest at the 18th day, but ergosterol content became highest at 22 days. These results suggest thatLentinula edodes liquid spawn is ready in 18 days after inoculation.KEYWORDS :

Simulation of gas-inducing reactor couples gas–liquid mass transfer and biochemical reaction

In the present study Euler–Euler's two fluid model coupled with mass transfer and biochemical reaction and experiment were applied to investigate hydrodynamic characteristic and bio-reaction parameters in self-induced bioreactor. Biochemistry parameters, like biomass, residual sugar concentration and dissolved oxygen concentration were measured. Higbie's penetration theory was applied to gas–liquid mass transfer and Monod's equation was used to build a growth model for yeast in self-induced bioreactor. The computational model was mapped on ANSYS CFX 10.0. The biomass, residual sugar and dissolved oxygen concentration predicted by numerical simulation were validated with results from experiments. The distribution of local biomass, residual sugar concentration and dissolved oxygen were successfully predicted by simulation, which reflect the effect of geometry of reactor and physical-chemistry conditions.

Fed-batch fermentation with glucose syrup as an adjunct for high-ethanol beer brewing

To produce a beer with a high ethanol content, preliminary research on fed-batch fermentation profiles with glucose syrup as an adjunct during the primary fermentation period was conducted. The ethanol concentration of the beer was elevated by feeding a glucose syrup into the fermentors at a later stage of primary fermentation. Fermentation trials were carried out using a typical lager strain, SC-9, with a pitching rate at 7.0 × 106 cells/mL. An all-malt wort (12.5°P) was employed and the primary fermentation temperature was 14 °C. Glucose syrup was supplemented when the concentration of residual reducing sugars was decreased to ~10 g/L. Results showed that the supplemented glucose was consumed rapidly and that the ethanol concentration in the final beer was raised to 67.9 g/L. Additional growth of yeast was observed after feeding accompanied by a low yield of ethanol (~0.46 g/g). Formation of diacetyl was enhanced by yeast growth and two additional peaks were obtained after feeding. The peak value of the diacetyl concentration was 1.90 mg/L. The fed-batch fermentation resulted in a beer with an overproduction of higher alcohols and esters, indicating that brewing under these experimental conditions led to an unbalanced flavour profile. Results of optimization demonstrated that the optimal conditions were found to be 15°P for initial wort extract, 10 °C for fermentation temperature and 20 × 106 cells/mL for yeast pitching rate, leading to total higher alcohols of 173.8 mg/L, total esters of 22.8 mg/L and an acetaldehyde concentration of 40.5 mg/L. A 12 day maturation and fermentation temperature of 8 °C was needed to reduce the acetaldehyde to 14.3 mg/L. Copyright © 2014 The Institute of Brewing & Distilling

Lactose and galactose content in cheese results in overestimation of moisture by vacuum oven and microwave methods

Moisture determination in cheese is a critical test for regulatory compliance, functionality, and economic reasons. Common methods for moisture determination in cheese rely upon the thermal volatilization of water from cheese and calculation of moisture content based on the resulting loss of mass. Residual sugars, such as lactose and galactose, are commonly present in cheeses at levels ranging from trace amounts to 5%. These sugars are capable of reacting with other compounds in cheese, especially under the thermal conditions required for moisture determination, to yield volatile reaction products. The hypothesis of this work is that residual sugars in cheese will be converted into volatile compounds over the course of moisture determination at a level sufficient to result in overestimated cheese moisture. A full-factorial statistical design was used to evaluate the effects of cheese type, sugar type, sugar level, method type, and all interactions. Cheddar and low-moisture, part-skim (LMPS) Mozzarella cheeses were prepared with 1, 3, and 5% added lactose or galactose, and subjected to either vacuum oven or microwave-based moisture determination methods. Browning index and colorimetry were measured to characterize the color and extent of browning. Volatile analyses were performed to provide chemical evidence of the reactions proposed. The presence of residual sugars altered moisture calculations as a function of cheese type, sugar type, sugar level, method type, and numerous interactions. At higher concentrations of residual sugar, the percentage moisture determinations were increased by values of up to 1.8. Measures of browning reactions, including browning index, colorimetry, and volatile profiles demonstrate that the proposed browning reactions played a causative role. This work establishes the need to consider cheese type, sugar type, sugar levels, and method type as a means of more accurately determining moisture levels.

Continuous ethanol production from sugarcane molasses using a newly designed combined bioreactor system by immobilized Saccharomyces cerevisiae

Continuous ethanol fermentation using polyvinyl alcohol (PVA), immobilized yeast, and sugarcane molasses (22 and 35°Bx) with 8g/L urea was run in a combined bioreactor system consisting of three-stage tubular bioreactors in series. The effect of the dilution rate (D) at 0.0037, 0.0075, 0.0117, 0.0145, 0.018, and 0.0282H(-1) on continuous ethanol fermentation was investigated in this study. The results showed that D had a significant effect on fermentation efficiency, sugar-utilized rate, ethanol yield, and ethanol productivity in this designed continuous fermentation system. The D had a linear relationship with residual sugar and ethanol production under certain conditions. The highest fermentation efficiency of 83.26%, ethanol yield of 0.44g/g, and the lowest residual sugar content of 6.50g/L were achieved at 0.0037H(-1) in the fermentation of 22°Bx molasses, indicating that the immobilization of cells using PVA, sugarcane pieces, and cotton towel is feasible and the established continuous system performs well.

Ostéosynthèse percutanée temporaire et greffe antérieure sélective dans les fractures thoracolombaires

In this preliminary investigation, a so-called Blenke cascade and plate heat exchanger bioreactor configuration were compared in terms of mixing characteristics, contamination free process, operational power costs and overall performance. At room temperature, fermentation was initially started as batch run and switched to continuous operation, when the residual sugars within the reactor were detected to be C ⩽ 1% (g/L). Samples from both configurations were taken and analyzed for ethanol and residual sugar content, as well as for any infection of the fermentation and lactic acid content, respectively. Mixing characteristics were studied by the residence time distribution method. Both geometries behaved as a finite number n of continuous stirred tanks in series, behaving as a plug flow with superimposed axial dispersion. The number of tanks in series n obtained in the plate heat exchanger configuration was 1.5–3 times larger than those in the Blenke cascade. The average ethanol productivity was Qp = 3.07 (g/L h) and Qp = 2.31 (g/L h) for cascade and plate exchanger configuration, respectively. The analysis of operational power costs indicates relevant differences between the two reactors at laboratory scale; however, systems with different types of pumps and viscosities are compared. From an industrial scale point of view, specific operational costs decrease with scale-up, as no mechanical mixing is needed in the fermenters.

Levan production by Zymomonas mobilis in batch and continuous fermentation systems

Levan production in batch and continuous fermentation systems by Zymomonas mobilis B-14023 was investigated. The culture medium used in both of the fermentation systems contained sucrose and various organic nitrogen sources. Maximum concentration of levan was produced with yeast extract among the nitrogen sources tested. Response surface methodology was used to investigate the effects of three factors on the concentration of levan in batch cultures of Z. mobilis. Maximum levan concentration was 40.2g/L and this concentration was reached at the optimum levels of process variables, which were 299.1g/L initial substrate concentration, 42.3h incubation time, and initial pH 6.0. Continuous fermentation experiments were done in packed bed bioreactor using Ca-alginate immobilized Z. mobilis cells. The highest levan concentration (31.8±0.21g/L) was obtained at a dilution rate of 0.14h−1 while maximum volumetric productivity (6.556g/(Lh)) was obtained at a dilution rate of 0.22h−1. Increasing the dilution rate resulted in decreased levan and increased residual sugar concentrations.

Effects of Nitrogen Composition on Fermentation Performance of Brewer's Yeast and the Absorption of Peptides with Different Molecular Weights

Four kinds of worts with different nitrogen compositions were used to examine their effects on fermentation performance of brewer's yeast. The absorption pattern of peptides with different molecular weights (Mw) in yeast cells during wort fermentation was also investigated. Results showed that both the nitrogen composition and level had significant impacts on the yeast biomass accumulation, ethanol production, and free amino nitrogen and sugars consumption rates. Worts supplemented with wheat gluten hydrolysates increased 11.5% of the biomass, 5.9% of fermentability, and 0.6% of ethanol content and decreased 25.6% of residual sugar content during wort fermentation. Moreover, yeast cells assimilated peptides with various Mw differently during fermentation. Peptides with Mw below 1 kDa decreased quickly, and the rate of assimilation was more than 50% at the end of fermentation, while those with Mw above 10 kDa almost could not be assimilated by yeast. All these results further indicated that the level and composition of wort nitrogen had significant impacts on the growth and fermentation performances of brewer's yeast, and peptides with Mw below 1 kDa were one of preferred nitrogen sources for brewer's yeast.

Yeast population diversity on grapes during on-vine withering and their dynamics in natural and inoculated fermentations in the production of icewines

In this study, attention has been focused on microbial ecology, during an on-vine withering period of 120days, of Mondeuse grapes, an autochthonous variety cultivated in the Western Alps in Europe, and on their fate during alcoholic fermentation. Laboratory fermentations have been followed in order to describe the yeast dynamics in both spontaneous and inoculated fermentations by means of culture-dependent and -independent methods (PCR-DGGE). The ability of Saccharomyces cerevisiae to take over the fermentation has also been assessed by means of minisatellite analysis. The chemical composition has been evaluated on the final products. A biodiversity of the grapes has been detected during the withering period, despite the predominance of Aureobasidium pullulans and Rhodotorula glutinis thus empathising that withering conditions could affect yeast populations.The spontaneous laboratory fermentation was characterized by a predominance of Hanseniaspora uvarum, Metschnikowia fructicola and S. cerevisiae. In the inoculated ones, counts of S. cerevisiae, belonging to the inoculated starter culture, became predominant after 7days, even though the PCR-DGGE analysis showed the starter profile for the entire fermentation period.Finally, when the S. cerevisiae isolates were characterized by the minisatellite analysis, it was determined that the inoculated culture was responsible for the alcoholic fermentation. As far as spontaneous fermentation is concerned, the autochthonous S. cerevisiae showed a good ethanol production yield, but left a high concentration of residual sugars.

An evaluation of different bioreactor configurations for continuous bio-ethanol production

In this preliminary investigation, a so-called Blenke cascade and plate heat exchanger bioreactor configuration were compared in terms of mixing characteristics, contamination free process, operational power costs and overall performance. At room temperature, fermentation was initially started as batch run and switched to continuous operation, when the residual sugars within the reactor were detected to be C⩽1% (g/L). Samples from both configurations were taken and analyzed for ethanol and residual sugar content, as well as for any infection of the fermentation and lactic acid content, respectively. Mixing characteristics were studied by the residence time distribution method. Both geometries behaved as a finite number n of continuous stirred tanks in series, behaving as a plug flow with superimposed axial dispersion. The number of tanks in series n obtained in the plate heat exchanger configuration was 1.5–3 times larger than those in the Blenke cascade. The average ethanol productivity was Qp=3.07 (g/Lh) and Qp=2.31 (g/Lh) for cascade and plate exchanger configuration, respectively. The analysis of operational power costs indicates relevant differences between the two reactors at laboratory scale; however, systems with different types of pumps and viscosities are compared. From an industrial scale point of view, specific operational costs decrease with scale-up, as no mechanical mixing is needed in the fermenters.

Comparison of North Italian and South Moravian wines on the base of their antioxidant activity, phenolic composition and sensory quality

In the present study, antioxidant capacity, phenolic composition and sensory evaluation of selected red and white wines originating from wine-growing regions of South Moravia and North Italy (wine-growing region Trident – Alto Adige) were investigated. The sensory analysis indicated that the evaluated wine samples were very similar. As far as basic the analytical parameters were concerned, concentrations of residual sugar were significantly higher in Moravian wines. Antioxidative characteristics were estimated by means of common spectrophotometric methods (total phenols, total anthocyanins, total flavanols, DPPH and FRAP) and thereafter compared. It was found out that the compared methods were highly significantly and positively correlated as far as their results were concerned. Individual phenolic compounds were detected by means of HPLC with DAD detection. In white wines, the content of GRP products was higher and this indicated that the quality of grapes used for making Moravian wines was lower. In red Moravian wines, the content of catechins (i.e. compounds responsible for the majority of phenolic substances and considered to be health-promoting compounds) was higher. This observation was corroborated also analytically, i.e. on the base of correlation with antioxidative characteristics.

Influence of fungal elicitors on biosynthesis of natamycin by Streptomyces natalensis HW-2

To investigate the effect of fungal elicitors on biosynthesis of natamycin in the cultures of Streptomyces natalensis HW-2, the biomass and filtrate of the broth from Aspergillus niger AS 3.6472, Penicillium chrysogenum AS 3.5163, A. oryzae AS 3.2068, and Saccharomyces cerevisiae AS 2.2081 were used to induce natamycin production in S. natalensis HW-2. The results showed that the biomass of P. chrysogenum AS 3.5163 could enhance the yield of natamycin from 0.639 to 0.875 g l(-1). The elicitor from the fermentation broth of P. chrysogenum AS 3.5163 showed the highest inducing efficiency with the yield of natamycin enhanced from 0.632 to 1.84 g l(-1). The elicitor that was cultured for 2 days showed the strongest inducing activity during the fermentation of S. natalensis HW-2 for 24 h, and the yield of natamycin was enhanced from 0.637 to 2.12 g l(-1). The biochemical parameters were examined at the end of fermentation and the results demonstrated that both the growth of cells and the concentration of residual sugar could be influenced. The residual sugar decreased from 5.03 to 4.27 g l(-1), and the biomass decreased from 10.26 to 6.87 g l(-1). Finally, the elicitor was identified as a low molecular weight substance with a similar polarity to that of butyl alcohol by primary qualitative analysis.

Physicochemical Properties, Lactic Acid Bacteria Content and Physiological Functionalities of Korean Commercial Makgeolli

The goal of this study was to characterize the physicochemical properties, lactic acid bacteria and physiological functionality of Korean commercial Makgeolli. We collected 60 kinds of raw and pasteurized Makgeolli commercially available in Korea. Their physicochemical properties, lactic acid bacteria content and physiological functionalities were determined. In the commercial raw Makgeolli, ethanol and residual sugar content ranged from 3.6% to 9.6% and 0.20% to 4.52%, respectively. Furthermore, the raw Makgeolli contained 3.50 to 101.9 mg% of amino nitrogen. In the pasteurized Makgeolli, ethanol content ranged from 4.0% to 7.0% and their residual sugar content were 0.98% to 7.57%. The raw Makgeolli contained 2.0 ~1.2 CFU/mL of lactic acid bacteria. Among several functionalities, the antihypertensive angiotensin I-converting enzyme inhibitory activities of EDS-14 raw Makgeolli and PWR-12 pasteurized Makgeolli were very high, at 89.9% and 87.0% respectively. The other functionalities were seen to be below 30% or not detectable. The -Glucan contents of the raw and pasteurized Makgeolli were noted as average, at 14.1% and 14.6%, respectively.

Performances comparison between three technologies for continuous ethanol production from molasses

Molasses are a potential feedstock for ethanol production. The successful application of anaerobic fermentation for ethanol production from molasses is critically dependent to the development and the use of high rate bioreactors. In this study the fermentation of sugar cane molasses by Saccharomyces cerevisiae for the ethanol production in a continuously stirred tank reactor (CSTR), an immobilised cell reactor (ICR) and a membrane reactor (MBR) was investigated. Ethanol production and reactor productivities were compared under different dilution rates (D). When using the CSTR, a decent ethanol productivity (Qp) of 6.8 g L−1 h−1 was obtained at a dilution rate of 0.5 h−1. The Qp was improved by 48% and the residual sugar concentration was reduced by using the ICR. Intensifying the production of ethanol was investigated in the MBR to achieve a maximum ethanol concentration and a Qp of 46.5 g L−1 and 19.2 g L−1 h−1, respectively. The achieved results in the MBR worked with high substrate concentration are promising for the scale up operation.

The Genetic Basis of Natural Variation in Oenological Traits in Saccharomyces cerevisiae

Saccharomyces cerevisiae is the main microorganism responsible for wine alcoholic fermentation. The oenological phenotypes resulting from fermentation, such as the production of acetic acid, glycerol, and residual sugar concentration are regulated by multiple genes and vary quantitatively between different strain backgrounds. With the aim of identifying the quantitative trait loci (QTLs) that regulate oenological phenotypes, we performed linkage analysis using three crosses between highly diverged S. cerevisiae strains. Segregants from each cross were used as starter cultures for 20-day fermentations, in synthetic wine must, to simulate actual winemaking conditions. Linkage analysis on phenotypes of primary industrial importance resulted in the mapping of 18 QTLs. We tested 18 candidate genes, by reciprocal hemizygosity, for their contribution to the observed phenotypic variation, and validated five genes and the chromosome II right subtelomeric region. We observed that genes involved in mitochondrial metabolism, sugar transport, nitrogen metabolism, and the uncharacterized ORF YJR030W explained most of the phenotypic variation in oenological traits. Furthermore, we experimentally validated an exceptionally strong epistatic interaction resulting in high level of succinic acid between the Sake FLX1 allele and the Wine/European MDH2 allele. Overall, our work demonstrates the complex genetic basis underlying wine traits, including natural allelic variation, antagonistic linked QTLs and complex epistatic interactions between alleles from strains with different evolutionary histories.

Xanthan gum production by Xanthomonas campestris pv. campestris 8004 using cassava starch as carbon source

Cassava starch is a main renewable bio-resource with low price and mass production in Guangxi, China. It was used as carbon source in growing Xanthomonas campestris pv. campestris 8004 (Xcc 8004) for xanthan gum production in this study. The xanthan gum yield of gelatinized cassava starch was higher than that of raw cassava starch; the maximal reducing sugar and amylase activity reached 14.30 g/L and 1.19U/ml, respectively. The maximal xanthan gum yield of 16.95 g/L was achieved with 30 g/L cassava starch as carbon source. The concentration of residual sugar was 6.82 g/L at the end of fermentation, and the conversion efficiency of sugar reached 73.12%. Thus, Xcc 8004 should be used as a competitive strain for xanthan gum production using cassava starch in industrial applications. Keywords: Xanthan gum, cassava starch, Xanthomonas campestris pv. campestris 8004, amylase activity

Production of ethanol from enzymatically hydrolyzed soybean molasses

Soybean molasses (SM) is a by-product of soybean meal concentrate. It is rich in sucrose, raffinose and stachyose. Stachyose and raffinose are not directly fermentable to ethanol but, when hydrolyzed, can be metabolized by Saccharomyces cerevisiae. In this work, we studied (1) the production of ethanol from natural SM by fermentation with S. cerevisiae, (2) the enzymatic hydrolysis of SM by α-galactosidase and the subsequent fermentation with S. cerevisiae (HF), and (3) ethanol production via the simultaneous hydrolysis and fermentation (SHF) of SM. The results showed that, although the fermentation of natural soybean molasses provided a fermentation yield of 72.9% under optimized conditions, hydrolyzed soybean molasses provided a fermentation yield 7.6% higher using the HF process and 8.2% higher using SHF. Both fermentation processes resulted in lower concentrations of residual sugar.

Comparison of sample preparation techniques for multielemental analysis of wine samples by ICP-MS

The aim of this study was the comparison of different sample preparation methods for multielemental ICP-MS analysis of wine samples. All investigated methods were previously published for the same purpose, but the comprehensive comparison was carried out in the frame of this study for the first time. Five wine samples of different residual sugar content (2 dry, 2 sweet and one extra fine quality dessert wine) were used from Hungarian wine districts. Due to the lack of certified reference materials method validation and cross-checking was carried out by using two different types of inductively coupled plasma mass spectrometers (ICP-MS), namely a quadrupole based ICP-MS equipped with a collision cell (ICP-CC-MS) and a high resolution sector field ICP-MS (ICP-SF-MS). The measured elements were Li, Mg, B, Al, Cu, Rb, Sr, Zr, Cd, Ba, Tl, Pb, Bi, U, Cr, Fe, Mn, Co, Ni, Zn, As, Mo and Ga.Sample preparation procedures were based on sample dilution, microwave digestion using nitric acid (in combination with and without evaporation prior to ICP-MS analysis) and a mixture of nitric acid and hydrogen peroxide. The investigation resulted that the optimal digestion method for the above-mentioned purpose is microwave digestion using nitric acid without evaporation. The advantages and disadvantages of the investigated methods are critically discussed.