No description available.

No description available.

Potato chips are very popular in the United States. Recently, an enormous interest in developing snacks from fruits and vegetables with high quality has been assessed. Mango, due to its characteristic flavor and nutritional value, is excellent for snack production. Osmotic dehydration (OD) as a pre-treatment and vacuum frying (1.33 kPa) processes were proposed to obtain high quality mango chips. Mango ?Tommy Atkins? slices were pre-treated with different OD concentrations (40, 50, and 65w/v), times (45, 60, and 70 min), and temperatures (22, 40, and 57oC). Physical and chemical properties (aw, pH, oBrix, sugar gain, water loss, and shrinkage) after OD were studied. The pre-treated slices were vacuum fried (1.33 kPa) at 120, 130, and 138oC and product quality attributes (PQA) (oil content, texture, porosity, color, microstructure, and carotenoid content) were determined. Microstructure of the chips was analyzed using an environmental scanning electron microscope. Effect of frying temperatures at optimum OD (65 w/v at 40oC) times was tested. The consumer tests showed that samples were all acceptable. The best mango chips process was the one with 65 w/v concentration for 60 min (pre-treatment) and vacuum frying at 120oC. Kinetic studies on oil content, texture, porosity, color, and carotenoid retention were performed. Oil absorption was modeled by a fractional conversion kinetic model. Absorption rate constant increased with frying temperature. Diameter changes in the chips, although not significant (P>0.05), followed an initial expansion to later decrease. Thickness of the slices increased (puffed) (around 60%) with time for all frying temperatures. Texture changes were for two frying periods: (1) water removal and crust formation and (2) slices became tougher and crispier and the end of frying. Porosity in the samples increased with frying, and a fractional conversion best described this phenomenon. Color *a (redness) increased with frying time and temperature and was modeled using a logistic model. Color *b (yellowness) increased up to 30 s of frying and then decreased. Carotenoids degradation followed a first order model, with a significant (P<0.05) decrease with frying temperature. Mango chips fried under atmospheric fryer had less carotenoid retention (25%) than with a vacuum fryer.

Saving energy is considered about by much more people nowadays. The energy use of industrial drying occupies a large part of total energy usage. Not only the governments, but also the industry owners are trying to find ways to cut down the usage of energy. The aim of this work is to find suitable technologies for industrial drying of berries which can be energy-efficient at the same time. More specifically, to find suitable dryers for drying aronia berry in Sweden. The research is based on secondary data collected by literature review. Good options for other circumstances like fluidized bed drying, freeze drying and solar drying were not discussed in detail. After the study, a continuous hot air dryer with explosion puffing system and heat pumping system seems to be the best solution for drying aronia berry in Sweden. It is easy to be controlled, cost acceptable (both capital and operational costs), environmental friendly and has high drying rate and high product quality. The extra means for improve drying process such as combined with dielectric or conductive dryer, adding pre-treatment such as osmotic drying were also discussed. Combined dryers can reduce the drying time and osmotic drying can cut the operation cost. Careful experiments shall be done before large amount of investment due to the complexity of dehydration.

Potato chips are very popular in the United States. Recently, an enormous interest in developing snacks from fruits and vegetables with high quality has been assessed. Mango, due to its characteristic flavor and nutritional value, is excellent for snack production. Osmotic dehydration (OD) as a pre-treatment and vacuum frying (1.33 kPa) processes were proposed to obtain high quality mango chips. Mango ?Tommy Atkins? slices were pre-treated with different OD concentrations (40, 50, and 65w/v), times (45, 60, and 70 min), and temperatures (22, 40, and 57oC). Physical and chemical properties (aw, pH, oBrix, sugar gain, water loss, and shrinkage) after OD were studied. The pre-treated slices were vacuum fried (1.33 kPa) at 120, 130, and 138oC and product quality attributes (PQA) (oil content, texture, porosity, color, microstructure, and carotenoid content) were determined. Microstructure of the chips was analyzed using an environmental scanning electron microscope. Effect of frying temperatures at optimum OD (65 w/v at 40oC) times was tested. The consumer tests showed that samples were all acceptable. The best mango chips process was the one with 65 w/v concentration for 60 min (pre-treatment) and vacuum frying at 120oC. Kinetic studies on oil content, texture, porosity, color, and carotenoid retention were performed. Oil absorption was modeled by a fractional conversion kinetic model. Absorption rate constant increased with frying temperature. Diameter changes in the chips, although not significant (P>0.05), followed an initial expansion to later decrease. Thickness of the slices increased (puffed) (around 60%) with time for all frying temperatures. Texture changes were for two frying periods: (1) water removal and crust formation and (2) slices became tougher and crispier and the end of frying. Porosity in the samples increased with frying, and a fractional conversion best described this phenomenon. Color *a (redness) increased with frying time and temperature and was modeled using a logistic model. Color *b (yellowness) increased up to 30 s of frying and then decreased. Carotenoids degradation followed a first order model, with a significant (P<0.05) decrease with frying temperature. Mango chips fried under atmospheric fryer had less carotenoid retention (25%) than with a vacuum fryer.

This thesis set out to answer 4 major questions: 1) Do elite hockey players arrive for a game hydrated and do they consume enough fluid to prevent dehydration over the course of a game? 2) Is hydration status repeatable between days and can an athlete who arrives dehydrated prior to training or competition become hydrated in the time before the start of activity? 3) What is the extent of dehydration (%body mass (BM) loss) necessary to change substrate oxidation and skeletal muscle metabolism during exercise in male and female subjects? 4) Will progressive dehydration have a negative effect on endurance performance? The first study evaluated the pre-game hydration status, sweat loss and fluid intake patterns of elite male junior ice hockey players during a game. Sweat loss was 3.2 ± 0.2L and exceeded net fluid intake (2.1 ± 0.1L). Mean BM loss was 1.3 ± 0.3%, but 8 out of 24 players lost between 1.8 - 4.3% BM. Despite abundant opportunities to hydrate during a hockey game, 33% of players did not drink enough to prevent sweat losses of ≥2% BM. The second study investigated 1) the day-to-day variability of morning urine specific gravity (USG) and consuming 600mL of water on the hydration status of hydrated and dehydrated (USG>1.020) subjects, and 2) the effects of consuming water or carbohydrate electrolyte solutions (CES) on hydration status of dehydrated subjects. Morning USG and hydration responses to the ingestion of 600mL of water were repeatable and mildly dehydrated subjects could reach euhydration within 45min after ingesting any type of fluid with no added effect of a CES. The next two studies (3 & 4) investigated the effects of mild progressive dehydration during 120min of exercise at ~65% VO2peak on whole body substrate oxidation and skeletal muscle metabolism, as well as cardiovascular, thermal, and mental responses in recreationally active, hydrated females and males. In both studies, muscle glycogenolysis was increased in the initial 60min of exercise in the dehydrated state when BM loss were ≤1%. Increased glycogenolysis appeared due to increases in core temperature during progressive dehydration as there were no differences in plasma epinephrine or the energy status of the cell (free ADP or AMP) between trials. Normal changes in physiological parameters accompanying exercise in a hydrated state were exacerbated with progressive mild dehydration. The final study determined the impact of dehydration on cycling performance. Active males cycled at ~65% VO2peak for 90min followed by a time trial (TT: 6 kJ/kg BM) with fluid to replace sweat losses (HYD) or without fluid (DEH). DEH subjects began the 90 min trial 0.6% dehydrated and progressively became more dehydrated with a BM loss of 1.4% at 45min, 2.3% at 90min, and 3.1% post-TT. TT performance was significantly compromised with ~2-3% BM loss (HYD 32 ± 4 vs. DEH 36 ± 3 min).

No description available.

No description available.

Dimethyl ether (DME), as a solution to environmental pollution and diminishing energy supplies, can be synthesized more efficiently, compared to conventional methods, using a catalytic distillation column for methanol dehydration to DME over an active and selective catalyst. In current work, using an autoclave batch reactor, a variety of commercial catalysts are investigated to find a proper catalyst for this reaction at 110-135 C and 900 kPa. Among the -Alumina, Zeolites (HY, HZSM-5 and HM) and ion exchange resins (Amberlyst 15, Amberlyst 35, Amberlyst 36 and Amberlyst 70), Amberlyst 35 and 36 demonstrate good activity for the studied reaction at the desired temperature and pressure. Then, the kinetics of the reaction over Amberlyst 35 is determined. The experimental data are described well by Langmuir-Hinshelwood kinetic expression, for which the surface reaction is the rate determining step. The calculated apparent activation energy for this study is 98 kJ/mol. / Chemical Engineering

Thesis PlanA (M.S.)--University of Wisconsin--Stout, 2009. / Includes bibliographical references.