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Abstract
Classical thermogravimetry and its modification with Knudsen cells were employed to quantitatively investigate the osmo-dehydration of apple pulp samples. The data allowed realization of the complex mechanism of the process, which is not a mere solvent depletion, since it also implies sugar exchanges between the apple tissue and the hypertonic syrup used to dehydrate the fruit. The comparison between different hypertonic syrups, all at the same water activity, showed that maltose is more effective than either sucrose or a mixture of sugars that mimics the saccharide content of the apple. The conclusions are supported by a thermodynamic analysis of the aqueous solutions of these sugars at a concentration level as large as that of the hypertonic syrups used for the osmo-dehydration process.
Fermentation trials were conducted in all-malt wort with mixed cultures of SaccharomycescerevisiaeWS 34/70 and one of two non-Saccharomycesyeast strains: Saccharomycodesludwigiiand Torulaspora delbrueckiiDSM 70607. Interactions were observed between the two yeasts during the alcoholic fermentation process started with eight different initial cell ratios ranging from 1:1 to 1:20 (Saccharomyces yeast : non-Saccharomyces yeast). Composition of the medium greatly affected the cell yield, degree of attenuation and ethanol concentration due to the maltose-negative characteristic of the non-Saccharomycesyeast strains. Starting cell ratios had less effect on the outcome of the fermentation experiments. S. cerevisiaelimited the growth of T. delbrueckiito a great extent, overgrowing it in the course of fermentation. On the other hand, S. cerevisiaedid not grow as dynamically in mixed culture with S. ludwigiias the composition of the medium would have suggested.
Chemical composition (moisture, ash, protein, fat, total carbohydrate, sucrose, fructose, glucose and maltose) of four types of biscuits and four gingerbreads were determined and moisture adsorption characteristics of samples were evaluated at 25 °C using the Novasina hygrometric technique. Generally, the GAB model gave the best description of the experimental sorption data; however, these findings were not statistically significant compared with the BET model. Gingerbreads absorbed higher amount of water (20–25 g/100 g on dry weight basis) at a w >0.70 in comparison to biscuits studied mainly due to higher content of sucrose and/or other simple saccharides. Monolayer moisture content evaluated by BET and GAB models were in general higher for the gingerbreads. Although the Novasina water activity meter is suitable for construction of sorption isotherms, in the lower range of a w values (i.e. <0.45) the water uptake is slightly underestimated.
This study was aimed to investigate the effect of carbon and nitrogen sources on the production of bioactive total dietary fibres (TDF) and glucans (α- and β-glucans) in submerged cultures of wild Ganoderma australe and commercial Pleurotus ostreatus, both of Greek origin. The contents of glucans and TDF were determined by using the respective Megazyme enzymatic kits. Glucose and yeast extract (YE) were suggested as appropriate carbon and nitrogen sources, respectively, for obtaining simultaneously high production of TDF and β-glucans by G. australe, which are compounds of great pharmacological interest, whereas maltose and YE were found favourable for high production of the above-mentioned functional components by P. ostreatus. The data obtained in this study provide useful information for further development of the studied mushroom fermentation process on a scale of the bioreactor aiming at enhanced TDF and β-glucan production.
In this study, the effects of various carbon sources for Morchella conica sclerotium formations were investigated under in vitro conditions. The formations of sclerotial initials, which improved from hyphae of Morchella conica , were obtained by using different carbohydrates. Vegetative mycelia were developed very well in agar media, containing malt extract (MEA), wheat (WA), potato dextrose (PDA) and complete medium yeast extract (CYM), however, moderate development occurred in defined media, containing glucose, sucrose, maltose and starch. The carbohydrate concentrations were prepared as 0.0%, 0.25%, 0.50%, 0.75%, 1.00% and 1.25%. Whole wheat agar and potato dextrose agar media consisting of glucose, sucrose and 0.25%, 0.75% and 1.25% starch excluded, while other cultural environments supported sclerotial formations. Sclerotial structures were examined morphologically and anatomically. The pigmentation changed from yellow to orange and brown. Time sclerotial formation varied from 10 days up to 7 months. Pigmentation, structure and quantity of sclerotia were taken as morphological criteria. Anatomical properties of sclerotia were obtained on light microscopy and scanning electron microscopy. Generally, sclerotial cells were very thick and spherical.
The aim of this study was to develop simple, rapid and reliable methods for the selective determination of Bifidus essensis from ACTIVIA (Danone) yogurts. The methods are based on a modified MRS medium (B-broth), which does not contain inhibitory additives. The sugar source of the medium is maltose, which is metabolized by the bifidobacteria applied in the probiotic products, and not by the normal microflora of yogurt ( Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus ). The redox potential of the medium was reduced with cysteine-HCl. Due to its reduced redox potential, the new bouillon is suitable for aerobic cultivation of bifidobacteria, while in agar form it needs anaerobic incubation. In bouillon form (MPN method) the incubation time is only 2 days compared to the 5-day requirement of the classical anaerobic plate counting methods. The B-broth in diluted form was successfully used in a RABIT (Don Whitley) equipment for selective impedimetric determination of bifidobacteria in Danone yogurts. The exact detection time of the Bifidobacterium counts in a good quality probiotic yogurt, containing bifidobacteria at a concentration of 10 7 to 10 8 CFU ml −1 is not more than 10 to 12 h (in contrast to the 5 days of classical anaerobic plate counting methods).
The role of zinc in beer production I.
Wort production
The most sensitive and time-consuming technological step of beer production is the fermentation of wort. Problems during fermentation will not only prolong production time but it will lead to the deterioration of beer quality. Most often it is due to low zinc concentration of the wort or the yeast. Due to lack of zinc the fermentation lasts longer, composition of fermentation by-products changes, maltose intake slows down, sedimentation ability and heat sensitivity of the yeast increase. In Part I of our work, the factors affecting the degree of zinc supply of wort were examined. During the examination of zinc supply of wort two kinds of beer were produced: all-malt beer and beer with adjunct. Change of zinc concentration was followed throughout the brewing process at every technological step. It was found that concentration of zinc gradually decreases during production of wort, and only a small fraction of the calculated amount appears in it. Wort made with adjunct has even lower zinc concentration than all-malt wort. In all malt wort 3.4%, while in wort containing adjunt only 0.4% of the zinc appeared in the wort. Yeast can absorb only the ionic form of zinc during fermentation, thus we had elaborated a method for the separation of the organic and inorganic form of zinc, which was followed by the determination of the concentration of ionic zinc in wort prior to fermentation.
An efficient in vitro plant regeneration system was established for elite, recalcitrant Malaysian indica rice, Oryza sativa L. CV. MR 219 using mature seeds as explant on Murashige and Skoog and Chu N6 media containing 2,4-dichlorophenoxy acetic acid and kinetin either alone or in different combinations. L-proline, casein hydrolysate and L-glutamine were added to callus induction media for enhancement of embryogenic callus induction. The highest frequency of friable callus induction (84%) was observed in N6 medium containing 2.5 mg l −1 2,4-dichlorophenoxy acetic acid, 0.2 mg l −1 kinetin, 2.5 mg l −1 L-proline, 300 mg l −1 casein hydrolysate, 20 mg l −1 L-glutamine and 30 g l −1 sucrose under culture in continuous lighting conditions. The maximum regeneration frequency (71%) was observed, when 30-day-old N6 friable calli were cultured on MS medium supplemented with 3 mg l −1 6-benzyl aminopurine, 1 mg l −1 naphthalene acetic acid, 2.5 mg l −1 L-proline, 300 mg l −1 casein hydrolysate and 3% maltose. Developed shoots were rooted in half strength MS medium supplemented with 2% sucrose and were successfully transplanted to soil with 95% survival. This protocol may be used for other recalcitrant indica rice genotypes and to transfer desirable genes in to Malaysian indica rice cultivar MR219 for crop improvement.
Food Science 2000 Orak H.H. (2006): Determination of starch and maltose content in some hybrid maize varieties by using
Currently gluten-free beer is not produced in Hungary for coeliacs. The goal of our research was to develop brewery products made of domestically grown millet (Alföldi 1) and buckwheat (Oberon) that are similar to traditional beer of barley malt regarding taste, aroma, consistency, colour, foam stability and alcohol content.On a micromalting equipment malts were made of buckwheat and millet. Beer was produced on pilot plant scale (50 l) with decoction process (mashing program with rests at 50 °C, 65 °C and 72 °C) and was supplemented with a highly heat-stable bacterial α-amylase, a fungal α-amylase and β-glucanase. Malts were evaluated by congress mashing (extract content, extract difference, pH, and colour); wort and final beer analyses were performed as well (pH, extract, iodine test, FAN, colour, bitterness, alcohol and extract content). Finally, sensory characterization was carried out. Difficulties with lautering were encountered during the brewing process with buckwheat. The analytical results indicated that the buckwheat and millet beer had different values compared with a typical barley beer with regard to pH, FAN, fermentability, and total alcohol. The extracts of the buckwheat and millet wort were lower, resulting in a final attenuation of 61.5% and 73.2%.In laboratory experiments optimal temperature of β-amylase found in domestically grown buckwheat (64 °C) and millet (62 °C) was determined by detecting maltose production with HPLC. Data was used to set the rest temperature of the enzyme during mashing. Inhibiting effect of certain substances on proteolytic enzymes was investigated by measuring the extract, FAN, and soluble nitrogen contents. Inhibition was detected in case of both raw materials, although to a different extent. Inhibition is influenced by tannins and polyphenols found in the grain (Chethan et al., 2008).
