Band 17, Heft 1

The β-glucosidase properties from one yeast isolate identified as Wickerhamomyces anomalus C4 were characterised. The β-glucosidase activity of W. anomalus C4 was 41.83 ± 0.25 mU/mL, and the optimum temperature and pH were 40 °C and 5.0, respectively. The glucose, 10% v/v of ethanol and 10 mmol/L of Cu 2+ inhibited the β-glycosidases activities. The isolate W. anomalus C4 had a stronger alcohol metabolism capacity than commercial Saccharomyces cerevisiae X16. Besides, fermentation with W. anomalus C4 alone and co-fermentations with S. cerevisiae X16 and W. anomalus C4 reduced the volatile acids content and the sourness value compared to S. cerevisiae X16 control. Moreover, inoculation with W. anomalus C4 could enhance volatile aroma richness and complexity of Rosa roxburghii wines, regardless of type or amount thereof. Therefore, the R. roxburghii native yeast isolate W. anomalus C4 may have some application potentials for R. roxburghii wine-making.

When in-line cells are used for obtaining residence time distribution (RTD) data from systems with short residence time, the signal distortion caused by the cell can compromise the results. A procedure to correct such distortion using convolution of signals in the time domain is proposed. First, the RTD of the cell is characterized, and then the E-curve of an RTD model is convoluted with the cell curve. The convoluted E-curve is fitted to the experimental data by adjusting the mean time and the model parameter. The procedure is demonstrated using a pilot scale pasteurization unit with two heaters, one cooler and six options of holding tube. Pulse experiments were performed, E-curves were obtained for each process step and five RTD models were tested. The convolution procedure was successful in removing the distortion caused by the detection cell, which was very significant for the holding tubes.

Fish oil was encapsulated with whey protein isolate (WPI) as wall material using a Micro-Fluidic Jet Spray Dryer. The effects of core/wall material ratio, drying temperature and total solids content on the properties of microcapsules were studied. Low core/wall material ratios at 1:5 and 1:3 resulted in high encapsulation efficiency (EE) and excellent oxidative stability of microparticles during storage. Reducing the inlet temperature from 160 to 110 °C remarkably decreased EE from around 99 to 64.8%, associated with substantial increases in peroxide value during storage. The total solids content mainly altered the morphology of microcapsules, showing little influence on EE and oxidative stability. We proposed that the different drying conditions impacted on particle formation behavior during spray drying, which could be a crucial factor responsible for the differences in the quality attributes of microparticles. A low core/wall material ratio and high drying temperature facilitated the formation of a rigid protein skin at droplet surface during drying, whereas a high solids fraction in the droplets could limit possible droplet shrinkage. These factors contributed positively to the encapsulation of the lipophilic core material.

Daqu, a Chinese liquor fermentation starter, contains all kinds of microorganisms and enzymes for Chinese liquor fermentation. The moisture content of Daqu significantly influence on the reproduction of microorganisms in Daqu. This work presents for the first time that determination of moisture content of Daqu with hyperspectral imaging. The characteristic spectrum of water is extracted based on comparative experiments with varying moisture content. The molds based on the full bands and feature bands were established by the support vector regression (SVR) method, which is used to predict moisture content of Daqu during fermentation process. The performance of the model based on the feature bands ( R 2  = 0.9870, root mean square error (RMSE) = 0.0091) is comparable to the full bands and the dimensions of the spectral information were significantly reduced. This work presents a novel, rapid and nondestructive approach for detecting the moisture content in Daqu and lays a foundation for the application of hyperspectral imaging.

The non-enzymatic browning (NEB) reaction between l -ascorbic acid (ASA) and glycine (Gly), including the effects of temperature (110–150 °C), time (10–150 min) and pH (4.5, 6.8, 8.0 and 9.5) on the formation of un-colored intermediate products (UIPs), browning products (BPs) and volatile products (VPs), were investigated. The results showed that pH had a remarkable effect on the reaction. The characteristics of zero-order kinetics for the formation of UIPs and BPs were discussed, and the corresponding activation energy ( E a ) was also calculated. When the pH was 4.5, the E a for the formation of UIPs was approximate 53.76 kJ/mol and less than that at other pH values; while the E a for BPs formation was approximate 94.06 kJ/mol and much higher than that at other pH values. The results suggested that an acidic environment facilitated the generation of UIPs, but did not remarkably promote the formation of BPs. The possible reaction pathway between ASA and Gly was proposed according to the experimental results.

This study was carried out to develop a prediction model for soluble solid content (SSC) of intact chestnut and to detect internal defects using nuclear magnetic resonance (NMR) relaxometry and magnetic resonance imaging (MRI). Inversion recovery and Carr–Purcell–Meiboom–Gill (CPMG) pulse sequences used to determine the longitudinal (T 1 ) and transverse (T 2 ) relaxation times, respectively. Partial least squares regression (PLSR) was adopted to predict SSCs of chestnuts with NMR data and histograms from MR images. The coefficient of determination ( R 2 ), root mean square error of prediction (RMSEP), ratio of prediction to deviation (RPD), and the ratio of error range (RER) of the optimized model to predict SSC were 0.77, 1.41 °Brix, 1.86, and 11.31 with a validation set. Furthermore, an image-processing algorithm has been developed to detect internal defects such as decay, mold, and cavity using MR images. The classification applied with the developed image processing algorithm was over 94% accurate to classify. Based on the results obtained, it was determined that the NMR signal could be applied for grading several levels by SSC, and MRI could be used to evaluate the internal qualities of chestnuts.

Effects of microwave power on the sensory properties (taste and aroma), chemical composition (catechins, caffeine, crude protein, and amino acid), active composition (flavones, triterpene, polysaccharide, and ergosterol) and antioxidant properties (superoxide free radical and hydroxyl radical scavenging abilities, reducing power) of Ganoderma lucidum fermented sea-buckthorn tea were investigated. G. lucidum fermented sea-buckthorn tea was dehydrated using microwaves at three power settings: 125, 250, and 500. After microwave treatment, a statistically significant difference in the chemical composition, active composition and antioxidant capacity ( p  < 0.05) of teas dried at different power settings was found. These results indicate that 250 W microwave treatments could effectively release and activate active components, improving the antioxidant activity of fermented tea.

Four colorants (control, carmine, beetroot extract and beetroot extract powder) and two methods (fermentation and heat treatment) were used in the production of sausages. The betalain content, total phenolic substance content and ORAC and TEAC values of concentrated beetroot extract were 562.08 mg/L, 27.72 mg GAE/mL, 33.96 µmol TE/mL and 35.70 mmol TE/L, respectively. The moisture content, pH value, lightness ( L* ), yellowness ( b* ) and odor values of heat-processed sausages were higher than those of fermented sausages. 2-thiobarbituric acid reactive substances (TBARS) values were lower in sausages with beetroot extract (20.51 μmol·MDA/kg) and powder (19.03 μmol MDA/kg) than for control and carmine treatments. The use of beetroot extract and powder positively affected the sensory appearance, color, flavor and overall acceptance of sausages. Thus, beetroot extract and powder could be used as alternatives to carmine in sausage production.