Effect Of Sugar Concentration Research Articles

Determination of pore edge tension from the kinetics of rupture of giant unilamellar vesicles using the Arrhenius equation: effects of sugar concentration, surface charge and cholesterol.

The pore edge tension (Γ) of a membrane closely intertwines with membrane stability and plays a vital role in the mechanisms that facilitate membrane resealing following pore formation caused by electrical and mechanical tensions. We have explored a straightforward procedure to determine Γ by fitting the inverse of the tension-dependent logarithm of the rate constant of rupture of giant unilamellar vesicles (GUVs) using the Arrhenius equation. The GUVs were prepared using a combination of 1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DOPG) and 1, 2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) in a physiological environment. The effects of sugar concentration, membrane surface charge density, and membrane cholesterol concentration on Γ have been investigated. The values of Γ increase with sugar concentration in the physiological buffer, measuring 9.6 ± 0.3, 10.4 ± 0.1, and 16.2 ± 0.1 pN for 40, 100, and 300 mM, respectively. A higher concentration of anionic lipids (70 mol% of DOPG) significantly reduces Γ. An increasing trend of Γ with cholesterol content was observed; specifically, the values of Γ were 11.9 ± 0.9, 13.9 ± 0.7, and 16.2 ± 0.4 pN for 15, 29, and 40 mol% cholesterol, respectively. Thus, the presence of higher anionic lipids in the bilayer led to a decrease in membrane stability. In contrast, the presence of higher sugar concentrations in the buffer and increased cholesterol concentration in the membranes enhanced membrane stability.

Effect of Sugar Concentrations on the Shelf Life of Pear Candies

The nutritional as well as medicinal benefits of pear fruit are well established and hence its consumption is highly appreciated by nutritionists and dieticians. The current study aims to develop a pear candy and to examine how the variation in sugar concentration alters the shelf life properties with respect to packaging material of pear candy. The study follows a novel approach by preparing pear candy and then keep on increasing sugar concentration while monitoring the change in shelf life. Besides it relates sugar concentration with type of packing material to be used. The physicochemical and sensory evaluation during the study revealed that the most suitable and stable pear candy was the one with least sugar concentration i.e. pear candy packed in polythene and have 20 percent of sugar concentration. It was then followed by the pear candy with same sugar concentration and having brown paper packed. Properties like moisture content, pH, ascorbic acid content and non-reducing content of the pear candy declined with the storage whereas acidity and total soluble solids showed hike with storage. Reduction in pH arranged from 4.55 percent to 3.50 percent. During storage period the acidity of pear candy was increased from 0.9 percent to 1.44 percent while Ascorbic acid content of pear candy was decreased from 3.75 percent to 2.97 percent. It concludes that lower the concentration of sugar and having an air tight packing makes the pear candy not only enhanced the shelf life but also the overall acceptability.

The Effect of Sugar Concentration and Citric Acid on Physicochemical Characteristics of the Pumpkins Syrup (Cucurbita moschata Durch)

Pumpkins (Cucurbita moschata Durch) are a food commodity with very high nutritional content, abundant production, and affordable prices, but their utilization has not been maximized. The syrup is a processed product made from sugar and water, with a minimum sugar moisture content requirement of 65%. The syrup is made from yellow pumpkins with food additives such as sugar, carboxyl methyl cellulose, citric acid, and lime. Variations in concentrations of sugars between 65% and 70% and citric acid between 0%, 0.1%, 0.3%, and 0.5%, are expected to affect pH, total dissolved solids, reduction sugars, vitamin C, and beta-carotene. The research objective was to study and determine the effects of cane sugar and citric acid concentrations on pumpkin syrup's physical, chemical, and organoleptic properties. pH, total dissolved solids, reducing sugars, vitamin C, and beta-carotene content were measured using a pH meter, a hand refractometer, the Nelson-Somogyi method, the iodometric method, and the spectrophotometer method, respectively, and organoleptic properties were evaluated using the sensory test. Results showed that variations in the addition of sugar and citric acid had a pH of 3.46-6.00, total dissolved solids 10.33-11.4 (obrix); reduction sugars of 19.4%-30.21%, vitamin C of 20.53-38.13 (mg/100 g); and beta-carotene of 1.24-2.82 mg/100 g. Pumpkin syrup made by adding 65% sugar and 0.5% citric acid (A1B3) was found to have the best concentration and was liked by panelists for its aroma, color, and taste.

Quantitative image analysis of protein foam microstructure and its correlation with rheological properties: Egg white foam

Recent advances in software development and machine learning algorithms are revolutionizing the way microstructures are analyzed and quantified in fields like biology and neuroscience. With this, comes an upsurge in the opportunities to apply these tools to study food microstructure to gain a deeper understanding of food structure-function relationships. This article shows how a recently developed deep-learning cellular segmentation algorithm, ‘ Cellpose ’ can be used to identify foam microstructure for further quantification. It successfully identified the air bubbles in a protein foam matrix, from microscopic images captured on a simple brightfield microscope. The segmentation algorithm allowed further quantification of microstructural parameters of the air phase (bubbles) and of the liquid phase (lamella) of the foams. Egg white foams were made with basic ingredients for meringue and the effect of sugar concentration and acidic conditions were studied. Microstructural parameters were analyzed in relation to the rheological responses of the foams. The underlying microstructural mechanisms governing the changes in the foams' stiffness and linearity of the viscoelastic response are shown. Sugar changes bubble size distribution by thickening liquid egg white, it also shortened the linear response to deformation due to its decreasing lamella thickness. Acidity re-shaped the bubbles into more ‘hexagon-like’ structures allowing more air to be incorporated in the foams. The shape of the bubbles under acidic conditions also makes the foams extend their linear response to deformation. The understanding achieved with data from the algorithm-identified microstructures presents a new way to characterize and study food foams. • Microscopy images of egg white foam were captured using a simple brightfield microscope. • The air and liquid phases were successfully distinguished by the Cellpose algorithm. • Quantitative microstructural parameters of both phases were obtained in subsequent image analyses. • Sugar decreases bubble size while acidity re-shapes bubbles into a hexagon-like shape. • Sugar and acid microstructural mechanisms alter the linear viscoelastic response of the foams. • Obtaining microstructural paraments leads to new insights into the study of foams.

Production of Cocoa Pulp Syrup by Utilizing Local Sugar Sources

The pulp of the cocoa fruit still has not economically viable yet. Its potency to be processed into fruit syrup is expected to increase its value added. Local sugar from palm and canes is still traditionally utilized to produce brown sugar. This study aimed to make fruit syrup by utilizing cocoa pulp and local sugar sources in West Sumatra with several variants (palm sugar, sugarcane, and market white sugar). The effects of sugar concentration on the quality of the syrup were also studied. Sensory evaluation by the hedonic method was performed and statistical analysis data were carried out using SPSS. Microbiological analysis and shelf-life testing also have been done. The results of this study showed that respondents preferred syrup with palm sugar to sugarcane because of its light brown color and distinctive sweetness. The microbiological test reported that the syrup could only be consumed for less than the 5th day in a sealed glass bottle if it was placed at room temperature. Meanwhile, the syrup placed in the refrigerator (5 0C) could keep until the 5th day

Effect of sugar concentration and fermentation time on secang kombucha drink

Secang kombucha drink is a fermented drink by Acetobacter xylinum and Sacharomyces cerevisiae using secang wood. Secang wood contains several nutritional contents that can be used in food diversification and sustainability of food for supporting food security. The use of secang wood is as a substitute for tea leaves in making of kombucha drinks. The study aims to determine the effect of fermentation and the concentration of sugar used on the manufacture of secang kombucha drink. The study was conducted using the factorial CRD (Completely Randomized Design) method, that is the addition of sugar concentration (G): 10%, 20%, 30% and fermentation time (F): 4 days, 7 days, 10 days, 13 days. The parameters observed were total acid, total soluble solid, pH, viscosity, and colour value. The results showed that the effect of addition of sugar concentration and fermentation time had a very significant effect on total acid, total soluble solid, pH, viscosity, and colour value. The best treatment is G2F3 treatment (the sugar concentration of 20% and the fermentation time of 10 days) with total acid of 0.9239%, total soluble solid of 20.8964°Brix, pH 2.9997, viscosity of 1.0906 Pa.s and colour value of 54.9170°Hue.

Monosaccharide-induced growth and higher order transitions in TPGS micelles

D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) is a nonionic surfactant with low critical micelle concentration. It usually forms spherical core-shell micelles in aqueous media. In this work, we show that these spherical micelles transform to ellipsoid and cylindrical structures upon the incorporation of commonly available monosaccharides, Glucose (GLC), mannose (MAN) and galactose (GAL). The aggregates have been characterized by dynamic light scattering (DLS), small angle neutron scattering (SANS) and nuclear magnetic resonance (NMR) spectroscopy. Our analysis is focused to discuss (a) the effect of sugar concentration, and (b) comparative ability of sugars in triggering structural transitions. It is shown that the transitions and micelle growth arose from the sugar-driven dehydration of head group region. With their higher affinity, sugar molecules approached the shell region and triggered expulsion of water molecules. Although the pattern of transition (micelle to ellipsoid to cylinder) remained common for each sugar, it began at lower concentration of GLC and GAL. NMR experiments showed structural reorganizations in TPGS molecule in the presence of sugar. The outcomes of our study can be applied to tune the viscosity of nonionic surfactant-based long-standing pharmaceutical dispersions.

The Effect of Sugar Concentration, Citric Acid Concentration and Storage Time on Orange Syrup’s pH Using Completely Randomized Factorial Design

One of the company in industrial product is orange syrup company. The quality of orange syrup can determine the success rate of company. Orange fruits contain acidic pH that can affect syrup quality depending on affecting factors. By using randomized factorial design, which consists of 3 factors, each factor consists of 2 factor levels, sugar concentration (50 gr and 70 gr), citric acid concentration (0.5 gr and 1 gr) and storage time (1 day and 3 days), this experiment was conducted using the axbxc fixed model with factorial 2x2x2 and 3 replications. Based on ANOVA table, there is a significant effect given by sugar concentration, citric acid concentration and storage time with F result = 0.532 > F table = 0.476. but there are no significant effect by conducted one or two factor only. The regression equation obtained is Y = 3.317 + 0.002 X1 + (-0.717) X2 + (-0.046) X3. For the correlations coefficient this research concluded that sugar concentration with value of 0.095 gives very low effect, citric acid concentration with value of -0.813 gives very strong opposite effect and storage time with value of -0.208 gives very low opposite effect on orange syrup’s pH.

Simultaneous vinegar fermentation from a pineapple by-product using the co-inoculation of yeast and thermotolerant acetic acid bacteria and their physiochemical properties.

In the present study, a potential newly isolated thermotolerant acetic acid bacteria (TH-AAB), Acetobacter pasteurianus FPB2-3, with ethanol and acetic acid-tolerant properties was found to be very effective in the production of vinegar from pineapple peels as an alternative, inexpensive raw material using simultaneous vinegar fermentation (SVF). The results showed that using whole pineapple peel with the addition of diammonium phosphate (DAP) and MgSO4 at an initial pH of 5.5 gave a slightly higher acetic acid content than that produced from the squeezed juice. Subsequently, the effects of sugar concentration and inoculation time of A. pasteurianus FPB2-3 on acetic acid production were examined. The results revealed that an increase in sucrose concentration led to the high production of ethanol, which resulted in the suppression of acetic acid production. Allowing for the inoculated yeast to ferment prior to inoculation of the AAB for 1 or 2days resulted in a longer lag time for ethanol oxidation. However, acetic acid accumulation commenced after 5days and gradually increased to the maximum concentration of 7.2% (w/v) within 16days. Furthermore, scaled-up fermentation in 6l vessels resulted in slower acetic acid accumulation but still achieved a maximum acetic acid concentration of up to 6.5% (w/v) after 25days. Furthermore, the antioxidant capacity of the vinegar produced from pineapple peels (PPV) was slightly higher than that produced from the squeezed juice (PJV), which was consistent with the higher total phenolic compound content found in the PPV sample. In addition to acetic acid, a main volatile acid present in vinegars, other volatile compounds, such as alcohols (isobutyl alcohol, isoamyl alcohol, and 2-phenyl ethanol), acids (3-methyl-butanoic acid), and esters (ethyl acetate, 3-methyl butanol acetate, and 2-phenylethyl acetate), were also detected and might have contributed to the observed differences in the odour and aroma of the pineapple vinegars.

Effect of sugar concentration (°Brix) and storage temperature on the time to visible growth of individual ascospores of six heat-resistant moulds isolated from fruit products

Heat-resistant moulds (HRMs) pose great challenges to processors of fruit-based products due to their thermal resistance and ability to grow across a broad range of conditions. Therefore, the quantification of the effect of inhibitory factors (conditions) on the growth of HRMs is very important to be used to prevent spoilage during shelf-life. This study assessed the minimum temperature and maximum sugar content (°Brix) for the growth of six HRMs (Byssochlamys spp. and Neosartorya spp.) previously isolated from fruit products. In addition, the time to form a visible colony (tv, days) was determined to assess biological variability of individual ascospores within same population. Heat activated ascospores (10 min at 80 °C) were spread plated (±100 spores) on acidified Potato Dextrose Agar (aPDA, pH 3.5) plates from which the °Brix was adjusted with fructose-glucose (1:1) to levels between 44 and 59 °Brix followed by incubation at 30 °C. To assess the effect of temperature, inoculated plates of aPDA were incubated at 4, 7, 8, 10, 12 and 14 °C. Three replicates (= 3 aPDA plates) were prepared per condition evaluated. The number of visible colonies were counted daily for up to two months. Probability distribution functions were then fitted in @Risk to the cumulative tv's. With regards to cold tolerance, B. nivea was the most cold sensitive as it had the least ability to germinate and form visible colonies at low temperatures (no growth when T ≤ 10 °C). On the other hand, N. hiratsukae was the most cold tolerant, being able to form visible colonies at temperatures ≥ 7 °C. Likewise, B. nivea was the most sensitive to increased °Brix values, whilst N. udagawae was able to grow out at the highest °Brix evaluated (59°/aw = 0.86). The tolerance of potential spoilage HRMs to high sugar levels and their ability to grow under chilled conditions represent a challenge for the microbial stability of high-sugar fruit products. Differences in individual tv's were mostly observed under conditions at the growth/no growth regions. For instance, individual tv's of B. nivea ascospores ranged from 24 to 46 days at 12 °C and those of N. udagawae ranged from 20 to 45 days at 59°Brix. The tv's data from each HRM and condition evaluated were then fitted to different statistical distributions (Exponential, Normal, Lognormal, Weibull, Logistic or Pareto) to allow the use of the obtained data in further Quantitative Microbial Spoilage Risk Assessment work for pasteurized fruit products.

Characteristics of Physichochemical and Microbiology of Rebon Shrimp Paste using Different Brown Sugar Concentration

Shrimp paste is a fermentation product of shrimp and has a distinctive smell and taste. The paste is made from a mixture of shrimp, fish salt and brown sugar. The purpose of this study was to determine the effect of sugar concentrations on the chemical, physical, microbiological and sensory characteristics of shrimp paste. Five differentconcentrations of brown sugar (0; 7.5; 10, and 12.5%) were applied. The shrimp paste was analyzed for their protein content, water content, amino acids, salinity, total sugar content, pH, colour test, viability of LAB and sensory. The sugar concentration significantly affected protein content, water content, total sugar, color, salt and organoleptic (p<0.05), but did not significantly affect on the water content, pH and LAB (p>0.05). The protein levels decreased with the increasing of sugar concentration. The brightness (L*) and redness (a*) were slightly decrease with the increasing of sugar concentration. The shrimp amino acid was dominated by glutamate acid, however, the concentration of amino acids decreased with the increasing concentration of the sugar. Addition of sugar to the shrimp paste improved the acceptance of the panelist, resulting higher score as compared to that of control. The best treatment in this study was the shrimp paste added with 10% sugar having the protein content 29.084%; water content 34.11%; sugar content 15.37%, pH 6.97; L 46.52; salt 13.63%; glutamate acid 23115.83 mg/kg, BAL <10 log CFU/mL and total organoleptic value 8.

Towards enhanced n-butanol production from sugarcane bagasse hemicellulosic hydrolysate: Strain screening, and the effects of sugar concentration and butanol tolerance

Robust strains are essential towards success of n-butanol production from lignocellulosic feedstock. To find a suitable strain to convert a non-detoxified hemicellulosic hydrolysate of sugarcane bagasse, we first assessed the performance of four wild-type butanol-producing Clostridium strains (C. acetobutylicum DSM 6228, C. beijerinckii DSM 6422, C. saccharobutylicum DSM 13864, and C. saccharoperbutylacetonicum DSM 14923) in batch fermentations containing either xylose or glucose at 30 g L−1 as sole carbon sources. C. saccharoperbutylacetonicum was selected after achieving butanol yields as high as 0.31 g g−1 on glucose and 0.25 g g−1 on xylose. In a 48-h fermentation containing a mixture of sugars (93% xylose and 7% glucose) that mimicked the hydrolysate, C. saccharoperbutylacetonicum delivered the highest butanol concentration (14.5 g L−1) when the initial sugar concentration was 50 g L−1. Moreover, the selected strain achieved the highest butanol yield (0.29 g g−1) on xylose-rich media reported so far. Meanwhile, C. saccharoperbutylacetonicum produced 5.8 g butanol L−1 (0.22 g g−1 butanol yield) when fermenting a non-detoxified sugarcane bagasse hemicellulosic hydrolysate enriched with xylose (30 g total sugars L−1). Although sugars were not exhausted (4.7 g residual sugars L−1) even after 72 h because of the presence of lignocellulose-derived microbial inhibitors, these results show that C. saccharoperbutylacetonicum is a robust wild-type strain. This microorganism with high butanol tolerance and yield on xylose can, therefore, serve as the basis for the development of improved biocatalysts for production of butanol from non-detoxified sugarcane bagasse hemicellulosic hydrolysate.

STUDI PEMANFAATAN DAUN SIRSAK (Annona murica linn.) SEBAGAI MINUMAN SEDUH DENGAN PENAMBAHAN TEH (Camelia sinensis) SEBAGAI MINUMAN FUNGSIONAL

Kepok banana (Musaparadisiaca formatypica) is one fruit that contains enough digestivefiber for the body. Kepok banana (Musaparadisiaca formatypica) is usually processed byfrying or steaming, bananas have a short shelf life and easily damaged. Therefore, to extendthe shelf life of bananas, fruit will be processed into fruit leather products. However, becausethe color of bananas are less attractive, the color addition will make the product preferred byconsumers. Terung belanda (Solanum betaceum cav. has a bright color and has enough fibercontent so well processed into fruit leather. The objective of this research was to find the besttreatment combination between kepok banana (Musaparadisiaca formatypica) and terungbelanda (Solanum betaceum cav.) sugar concentration to produce a good physical andchemical properties and favored by consumers. The research was also to find out the effect ofsugar concentration addition to physical, chemical and organoleptic fruit leather banana andterung belanda (Solanum betaceum cav.). Treatment applied was A1: kepok banana(Musaparadisiaca formatypica) mashed 50%: terung belanda ((Solanum betaceum cav)mashed 45%: sugar 5%; A2: 45%: 40%: 15%; A3: 40%: 35%: 25%. Fruit leather is then testedorganoleptically including color, flavor, taste and texture and was chemically tested including moisture content, total acid, pH, anthocyanin and fiber. The result of the research shows thatA1 treatment: 50% banana porridge: terung belanda porridge 45%: 5% sugar produces thebest fruit leather product in terms of water content, total acid, pH, anthocyanin, fiber, aroma,taste, and texture

Heterotrophic cultivation of Auxenochlorella protothecoides using forest biomass as a feedstock for sustainable biodiesel production

BackgroundThe aim of this work was to establish a process for the heterotrophic growth of green microalgae using forest biomass hydrolysates. To provide a carbon source for the growth of the green microalgae, two forest biomasses (Norway spruce and silver birch) were pretreated with a hybrid organosolv-steam explosion method, resulting in inhibitor-free pretreated solids with a high cellulose content of 77.9% w/w (birch) and 72% w/w (spruce). Pretreated solids were hydrolyzed using commercial cellulolytic enzymes to produce hydrolysate for the culture of algae.ResultsThe heterotrophic growth of A. protothecoides was assessed using synthetic medium with glucose as carbon source, where the effect of sugar concentration and the carbon-to-nitrogen ratio were optimized, resulting in accumulation of lipids at 5.42 ± 0.32 g/L (64.52 ± 0.53% lipid content) after 5 days of culture on glucose at 20 g/L. The use of birch and spruce hydrolysates was favorable for the growth and lipid accumulation of the algae, resulting in lipid production of 5.65 ± 0.21 g/L (66 ± 0.33% lipid content) and 5.28 ± 0.17 g/L (63.08 ± 0.71% lipid content) when grown on birch and spruce, respectively, after only 120 h of cultivation.ConclusionsTo the best of our knowledge, this is the first report of using organosolv pretreated wood biomass hydrolysates for the growth and lipid production of microalgae in the literature. The pretreatment process used in this study provided high saccharification of biomass without the presence of inhibitors. Moreover, the lipid profile of this microalga showed similar contents to vegetable oils which improve the biodiesel properties.

Effects of sugar concentration on mango wine composition fermented by Saccharomyces cerevisiae MERIT.ferm

SummaryThis study investigated the effect of initial sugar concentrations (°Brix of 17, 23 and 30) on mango wine composition fermented by Saccharomyces cerevisiae MERIT.ferm. It was found that growth rate and maximum cell population were inversely correlated with initial sugar levels with the fastest growth rate and largest cell population in the low sugar fermentation. However, the cell population in the low and medium sugar fermentation declined significantly (from 8.7 and 8.2 log to 2 and 2.8 log, respectively) relative to the high sugar fermentation in which cell populations remained stable upon reaching the stationary phase (7.7 log). Glycerol production increased with increasing sugar content in low (13.4 g L−1), medium (14.5 g L−1) and high (15.9 g L−1) sugar fermentation. In addition, high sugar fermentation had a negative impact on volatile production with significantly lower amounts of acetate esters (1.5 mg L−1) but more acetic acid (0.54 g L−1) compared to the low (5.0 mg L−1 and 0.44 g L−1, respectively) and medium (3.7 mg L−1 and 0.49 g L−1, respectively) sugar fermentations. Furthermore, volatiles especially terpene hydrocarbons (α‐caryophyllene was released) present in mango juice were significantly metabolised after fermentation, while numerous new volatile compounds (such as isobutyl alcohol, isoamyl alcohol, ethyl and acetate esters) were produced. Some terpene alcohols were released and converted into corresponding acetyl esters. This may indicate that the mango wines fermented with different levels of sugars would have different flavour aromas.

Aspergilli with Neosartorya-type ascospores: heat resistance and effect of sugar concentration on growth and spoilage incidence in berry products

This study focused on four different heat resistant aspergilli: two strains of Aspergillus hiratsukae (≡Neosartorya hiratsukae), one strain of Aspergillus neoglaber (≡Neosartorya glabra), and one strain of Aspergillus thermomutatus (≡Neosartorya pseudofischeri), all isolated from spoiled pasteurized products. Their heat-resistance, the sugar concentration limiting their germination and growth in berry-based media, and a possible relation between the contamination levels of the raw materials used and the spoilage incidence in strawberry jams were assessed. Heat resistance data obtained from thermal death curves showed that the D values of the strains tested ranged between 3.7 and 13.5min at 87°C; 1.5 and 3.5min at 90°C; and 0.3 and 0.4min at 95°C in glucose solution. Similarly, D values ranged between 3.3 and 15.4min at 87°C; 1.3 and 4.3min at 90°C; and 0.3 and 0.6min at 95°C in strawberry-based formulation. For all strains, the corresponding z-values ranged between 5.7 and 8.3°C in glucose solution and from 5.7 to 8.4°C in strawberry formulation. With regard to the limitation of fungal germination and growth in fruit-based media, sucrose concentrations required to avoid growth varied between 45.0 and 55.0% for strawberry medium and between 42.5% and 50.0% for blueberry medium. Spore inactivation was observed below aw 0.88–0.91 for strawberries and aw 0.87–0.90 for blueberries; above 49.7–56.5°Bx for strawberries and 49.6–56.0°Bx for blueberries. The threshold optical refractometric residue proved strain-dependent, but substrate-independent, as for each strain the highest Brix degree value at which germination occurred was the same on both media, despite their different sucrose concentrations. With regard to the relation between contamination of raw materials by heat-resistant mould spores and spoilage incidence on final product, an equation was modelled to estimate the occurrence of fungal spoilage in strawberry jams for low contamination levels (26–46CFU/kg). Although it could not be used as a definitive tool to predict final spoilage in such of products, it could give important practical information to jam producers in preventing spoilage of their products.

Dehydration kinetics of Musa acuminata in osmotics and microwave drying

To develop a product, banana chips of high consumer acceptability, the banana slices of 2 mm thickness were first osmotically pretreated and then convectively dried in oven at constant air temperature of 40°C to safe moisture level followed by microwave drying. Different experimental combinations of osmotic process parameters, i.e., palm sugar concentration, solution temperature and immersion time is to be tried using Box-Behnken design of experiments. Response surface methodology has to be used to investigate the effect of sugar concentration (40-45°Brix), solution temperature (40-60°C), and immersion time (30-150 min) on the water loss and solute gain. The experimental data was fitted to different empirical kinetic models including Peleg, Page and Midilli equations. Determination of coefficient (R2), root mean square error and mean relative deviation modulus were used for determination of the best suitable model. The present work shows that the Peleg empirical model satisfactorily described the dehydration kinetics for osmotic dehydration where as page and Midilli for microwave drying.

Comparison of various carbohydrates for hydrogen production in microbial electrolysis cells

ABSTRACTThe direct production of hydrogen from various carbohydrates of lignocellulosic biomass is examined by using single-chamber membrane-free microbial electrolysis cells. The mixed microbial culture was enriched with 20 mmol L−1 2-chloroethane sulphonate and 10 mmol L−1 sodium acetate as a carbon source. Hydrogen was produced from all carbon sources used, including monosaccharides (glucose, galactose, mannose, xylose and arabinose) and disaccharides (maltose, saccharose and cellobiose). Hydrogen gas (18 mL) was produced using 3.33 mmol L−1 maltose and 20 mL of hydrogen was produced using cellobiose after 14 d of operation. Methane was not produced under any of the tested conditions. The effects of sugar concentration were also examined. Hydrogen production rates varied from 0.01 m3 d−1 m−3 to 0.09 m3 d−1 m−3. The maximum hydrogen yield ranged from 14% to 111%. Our results suggested that carbohydrates, such as maltose and cellobiose, are suitable carbon sources for hydrogen production, when methanogens are suppressed.

Effects of sugar concentration, natural ventilation and supporting materials on the growth of in vitro strawberry plantlets (Fragaria ananassa Duch.) and on the survival rate of ex vitro plantlets

Effects of sugar concentration, natural ventilation and supporting materials on the growth of in vitro strawberry plantlets (Fragaria ananassa Duch.) and on the survival rate of ex vitro plantlets

Osmo-convective dehydration of sweet potato (Ipomoea batatasL.)

The effect of sugar concentration and different drying temperatures on the quality of osmotically dehydrated sweet potato was determined. Sweet potato cubes were osmotically dehydrated in sugar syrup concentrations of 50, 60 and 70oBrix for 48 hours and thereafter samples were dried using tray drier at temperatures of 55, 65 and 75 oC. The quality of the samples was determined in terms of bulk density, water activity, sugar gain, hardness, shrinkage ratio and color. The drying rate decreased with increase in drying time and became uniform for 55, 65 and 75oC drying temperature irrespective of concentration of sugar solutions, whereas at initial stage higher decrease in drying rate was found in 75oC at 50 o Brix. Bulk density was maximum for sugar solution concentration of 60oBrix at 65oC (46.52 kg/m3). The maximum water activity was found for sample having sugar concentration of 50 o Brix and drying temperature of 55oC and the minimum value of water activity was attained for sliced sample at a drying temperature of 75oC and sugar concentrations of 60oBrix. It was observed that the sugar gain was highest in samples dipped in sugar solutions of concentration 70 oBrix and lowest in the samples of sugar solution concentration of 50oBrix.