Adrian Caprita - Academia.edu (original) (raw)

Papers by Adrian Caprita

Abstract—Protein quality of soybean meal (SBM) is linked to both the reduction of anti-nutritiona... more Abstract—Protein quality of soybean meal (SBM) is linked to both the reduction of anti-nutritional factors (ANFs), and the optimization of protein digestibility. Inadequate heating fails to completely destroy the ANFs. Excessive heating reduces the availability of lysine via the Maillard reaction and possibly, to a lesser extent, other amino acids, and decreases the protein nutritive quality. The objective of the study was the analysis of some chemical indices for determining SBM quality, and their correlation with biophysical indices. The experimental data revealed that urease index (UI) is useful to determine if the soybean meal has been heated enough to reduce ANFs, but it is not useful to determine excessive heat treatment. KOH solubility is a good index for determining over processing, but it is not a sensitive index for monitoring under processing of soybean meal. Combing protein dispersibility index (PDI) and UI could be useful to monitor soybean quality. The investigated bio...

Dietary fibre (DF) includes all non-starch polysaccharides resistant to digestion in the small in... more Dietary fibre (DF) includes all non-starch polysaccharides resistant to digestion in the small intestine and fermentable in the large intestine, and consists of a mixture of components with a varying degree of solubility. Wheat contains substantial amounts of both soluble (SDF) and insoluble (IDF) dietary fibre. The predominant water SDF in wheat is arabinoxylan (6-8%). The main polysaccharide constituents of wheat endosperm cell walls are arabinoxylans, whereas arabinoxylans and β-glucans predominate in wheat aleurone layers, arabinoxylan and cellulose predominate in cell walls of pericarp/testa. Soluble polysaccharides give viscous aqueous solutions. The viscous properties depend on molecular weight and molecule size (linear or branched), ionically charged groups, surrounding structures, and concentration of DF. In aqueous solutions, water molecules penetrate the amorphous regions of soluble DF. The increase in viscosity is explained by formation of Ca 2+ bridges and hydrogen bond...

 Abstract—Cereal grains contain various amounts of non-starch polysaccharides (NSP), which are c... more  Abstract—Cereal grains contain various amounts of non-starch polysaccharides (NSP), which are composed predominantly of arabinoxylans (pentosans), s-glucans and cellulose. The detrimental effect of soluble NSP is mainly associated with the viscous nature of these polysaccharides and their physiological effects on the digestive medium. Experiments were conducted to investigate the influence of some extraction conditions on the viscosity of wheat and barley aqueous extracts. Water extract viscosities (WEV) appeared to be related to the particle size of the meals obtained after grinding. The study shows that viscosities of aqueous extracts of wheat and barley samples have maximum values at 0.5 mm size. The experiments carried out at different extraction temperatures revealed that the optimum temperature for extraction the soluble fraction of NSP is 40°C. At lower temperature (20°C) the extractability of NSP soluble fraction was lower, and at higher temperature (60°C) viscosity increa...

Cereal grains are major sources of dietary fiber (DF), an important component of food and an impo... more Cereal grains are major sources of dietary fiber (DF), an important component of food and an important contributor to human health. Based on their water solubility DF are classified as soluble dietary fiber (SDF) and insoluble dietary fiber (IDF). The physical and physiological properties of dietary fibers are of commercial and nutritional importance. Food processing is mostly based on heating. Heat treatment alters the properties of plant cell wall and modifies the composition and solubility of fibers. The experiments had in view the effect of dry heat treatment (in forced air oven, and microwave oven) on the bioavailability of carbohydrates. The research investigated the dynamics of released glucose (RG) from heat treated whole wheat and barley flour, during in vitro gastric and intestinal digestion. RG after 240 minutes of intestinal digestion revealed a higher digestibility of carbohydrates in wheat samples heated at 150°C for 10 and 15 minutes and in barley samples heated for 5 minutes. When the heating time of the barley samples was longer, the digestibility of carbohydrates decreased due to the formation of higher starch resistant to amylase action. Carbohydrates digestibility of wheat samples exposed to microwaves was lower compared with untreated samples. We observed a moderate increase in carbohydrate digestibility in barley samples after microwave exposure for 30 and 60 seconds. The digestibility decreased after 90 seconds of microwave exposure, due to accelerated Maillard reactions and increase in the proportion of resistant starch.

Changes in particle size, solubility and chemical structure of different fiber components can cau... more Changes in particle size, solubility and chemical structure of different fiber components can cause changes in the bioavailability of some nutrients. Numerous studies have shown a reduction in apparent digestion of proteins in the gastrointestinal tract caused by direct and indirect processes. Endogenous nitrogen losses are due to increased secretion of digestive juices and increased desquamation in the presence of dietary fiber. Food fibers reduce digestion of food and endogenous proteins. Food processing can improve the bioavailability of proteins. Reduction of thermally latent antinutritional factors, such as trypsin inhibitors, phytates and polyphenols, as well as partial denaturation of proteins by heat treatment contributes to their digestibility. Protein quality in processed foods decreases primarily due to reduced lysine bioavailability. Experiments revealed an increase in protein digestibility (PD) in whole wheat flour heated samples in a forced air oven at 150°C over 0-10 ...

The aim of this study was to compare the total protein values obtained in heparin plasma of chick... more The aim of this study was to compare the total protein values obtained in heparin plasma of chickens by a spectrophotometric technique (biuret method), and the values obtained on the same day in the same samples by refractometry. The results obtained by refractometry (average value 2.638±0.153g%) were higher than those obtained by the spectrophotometric method (average value 2.441±0.181g%). There was a low correlation (r = 0.6709) between the total protein values, determined with both methods. Protein is the major determinant of plasma refractive index, but glucose contributes too. The refractometric method is not recommended in chickens for the determination of total protein, because avian blood glucose concentration averages about twice than in mammalian blood.

Different hydration characteristics of dietary fibers are related to their chemical structure. Pr... more Different hydration characteristics of dietary fibers are related to their chemical structure. Processing conditions can modify the physical properties of the fiber matrix and consequently affect their hydration properties. Microwave treatment of cereals and legumes is able to increase the water retention capacity (WRC), which often is required in baked products to make the texture harder and crispy. The present study investigated the effect of microwave radiations on WRC of wheat and barley submitted to in vitro simulated digestion. A slightly higher WRC was observed in treated wheat, from 0.96 g water/g DM (untreated) to 1.015 g water/g DM (treated for 30 s). Greater WRC values were recorded in barley, due to the higher β-glucan content: from 1.026 g water/g DM (untreated) to 1.361 g water/g DM (treated for 30 s).

The presence of microorganisms in milk is of great importance for safety, quality and public heal... more The presence of microorganisms in milk is of great importance for safety, quality and public health. Rapid methods are those that provide results more quickly than the conventional plating methods. Adenosine Tri-Phosphate (ATP) is the most popular biochemical index as it is ubiquitous in cellular life forms and can be detected rapidly using bioluminescence reactions. Electrical conductivity and impedance measurement techniques have proved useful for bacteria counting in commercial applications. During the process of microbial metabolism, large molecules (carbohydrates, fats and proteins) are broken down into smaller and more highly charged components, e.g., fatty acids, amino acids and other organic acids. The highly charged molecules cause a change in the media’s electrical conductivity/resistance. These changes indicate the presence of microorganisms in the original sample. We studied the correlation between the ATP content and the electrical conductivity in raw milk.

Ionized calcium is the physiologically active fraction of serum calcium and therefore its evaluat... more Ionized calcium is the physiologically active fraction of serum calcium and therefore its evaluation is an important clinical parameter both in mammals and birds. In the present study, concentration of total calcium (tCa), ionized calcium (iCa) based on the serum albumin level and on the total protein content, and corrected total calcium (ctCa) based on the serum albumin level were evaluated, and the correlation between these biochemical parameters was investigated in broiler chickens. The average serum iCa was 4.91±0.49g/dL representing 51.76±0.53% from the ctCa. The correlation coefficient between tCa and albumin (r = 0.8608) was greater than that between tCa and total protein (r = 0.7997). Our study illustrated that iCa and ctCa concentrations calculated from tCa and albumin are better indicators of calcium homeostasis than tCa concentrations alone.

Thermal treatment can modify the physicochemical properties of dietary fiber (DF). The study was ... more Thermal treatment can modify the physicochemical properties of dietary fiber (DF). The study was conducted to evaluate the effect of thermal processing on soluble DF fraction of wheat samples subjected to in vitro gastric and intestinal digestion. Samples were treated by heating in a forced air oven at 150oC for 5, 10 and 15 minutes, and by exposing to radiations in a microwaves oven for 30, 60 and 90 seconds. The effect of digestive enzymes action on the soluble DF fraction was evidenced by the variation in the dynamic viscosity (DV) of the supernatant collected after gastric and intestinal incubation. Regardless of the heat treatment, DV increased during processing and during digestion. Maximum DV values were observed at 240 minutes of intestinal digestion, after 90 seconds exposure to microwaves.

Cereals and cereal by-products are the main dietary sources of carbohydrates for humans and anima... more Cereals and cereal by-products are the main dietary sources of carbohydrates for humans and animals. The most common dietary fibers (DF) in cereals are non-starch polysaccharides (NSP). Arabinoxylans and β-glucans are the two most important water-extractable dietary fiber polysaccharides in cereal food products. The structure and molecular weight distributions of these polymers determine their physical properties like viscosity, extractability, solubility and gelling behavior, as well as nutritional properties. Production of cereal foods include processing such as extrusion, flaking, milling and bread making which may have great effects on DF, especially on their molecular weight distributions. Experiments were conducted on some cereals to investigate the water extract viscosity (WEV), the correlation between WEV and NSP, and the influence of processing on the soluble fraction of DF, evidenced by the viscosity of aqueous extracts. The comparison between WEV and the soluble, insoluble and total NSP values, revealed that the WEV are high positively correlated (r = 0.9707) with the soluble NSP content and decrease in the following order: oats>barley>wheat> triticale>corn>rice. Processed cereals have much higher WEV than the unprocessed grains. Viscosities of aqueous extracts vary with fiber content. The flaking process increased the soluble fiber content in wheat, barley and oats, and subsequently the water extract viscosity was also increased. Results revealed a high positive correlation (r = 0.9268) between WEV and DF content of processed wheat, barley and oats. WEV of processed wheat, barley and oats are not correlated with the total carbohydrates content.

Starch is the most important digestible polysaccharide present in foods and feeds. The starch con... more Starch is the most important digestible polysaccharide present in foods and feeds. The starch concentration in cereals cannot be determined directly, because the starch is contained within a structurally and chemically complex matrix. Fine grinding and boiling in dilute HCl are preparative steps necessary for complete release of the starch granules from the protein matrix. Starch can be determined using simple and inexpensive physical methods, such as density, refractive index or optical rotation assessment. The polarimetric method allows the determination even of small starch contents due to its extremely high specific rotation. For more accurate results, the contribution of free sugars is eliminated by dissolution in 40% (V/V) ethanol. The influence of other optically active substances, which might interfere, is removed by filtration/clarification prior to the optical rotation measurement.

The biological availability of nutrients is of great importance in formulating a balanced ration ... more The biological availability of nutrients is of great importance in formulating a balanced ration to attain maximum productivity in animals. In vitro digestibility techniques are useful to provide a quick, inexpensive, and precise prediction of in vivo amino acid and protein digestibility for humans and animals. The objectives of the present study were to determine the in vitro dry matter solubility (DMS) and protein digestibility (PD) of barley grains. Two experiments were conducted: experiment 1 simulated gastric digestion and experiment 2 simulated gastric and small intestinal digestion. DMS in gastric digestion showed an increase with the incubation time. DMS of barley grains ranged in experiment 1 from 0.1067 g/g at 30 minutes digestion time, to 0.1475 g/g at 120 minutes digestion time. Samples showed higher DMS and PD after pepsin-pancreatin digestion than after pepsin digestion. DMS increased with 19.22% and PD increased with 16.18% when pepsin digestion was followed by 240 mi...

The research investigated the dynamics of released glucose from whole wheat flour during in vitro... more The research investigated the dynamics of released glucose from whole wheat flour during in vitro gastric and intestinal digestion. Two experiments were conducted. Experiment 1 (gastric digestion) was an enzymatic hydrolysis with a pepsin solution at pH 2.0 and 37°C for 120 minutes. In experiment 2, first step was followed by the hydrolysis with the multi-enzyme pancreatin (intestinal digestion), at pH 6.8 and 37°C for 4 h. The released glucose (RG) and the refractive index (RI) were determined from the supernatant obtained after centrifugation. Experiments showed an initial increase in the glucose released from 1 g wheat up to 0.472 mg/mL after 1 h of gastric digestion, then followed by decrease. The lowest value was recorded after 2 hours of gastric digestion (0.332 mg/mL). The concentration of the reducing sugars increased throughout the intestinal digestion from 0.549 mg/mL up to 1.990 mg/mL, as a result of starch hydrolysis to dextrins, maltose and then to glucose. The high pos...

The dynamics of released glucose (RG) and refractive index (RI) in the supernatant obtained durin... more The dynamics of released glucose (RG) and refractive index (RI) in the supernatant obtained during in vitro gastric and intestinal digestion of whole barley flour was studied. The in vitro digestion consisted of a two-step enzymatic procedure: (1) initial simulation of gastric digestion using pepsin and (2) simulation of small intestine digestion using multi-enzyme pancreatin. Experiments on 1 g barley flour showed an initial increase in RG concentration up to 0.379 mg / mL at one hour from the onset of gastric digestion, then a decrease in concentration, reaching the lowest value in 2 hours of gastric digestion (0.126 mg/mL). The concentration in reducing sugars increased throughout the intestinal digestion from 0.422 mg/mL up to 2.824 mg/mL, as a result of starch hydrolysis to dextrins, maltose and then to glucose. RI can give information on the amount of glucose released during digestion due to the high positive correlation found between RG and RI (r = 0.761).

Chlorophyll is one of the major components of chloroplasts and represents a variable in assessing... more Chlorophyll is one of the major components of chloroplasts and represents a variable in assessing the physiological status and photosynthetic performance of plants. The purpose of the study was to evaluate the microwave irradiation effect on the chlorophyll content of Hordeum vulgare L. The chlorophyll content was determined at 14 days after the irradiation treatment, using the portable chlorophyll meter SPAD- 502 (Konica Minolta). We observed variations in the chlorophyll content when applying different power values of the radiations and different times of exposure. The chlorophyll content was lower for 720W irradiation power than for 400W, for all studied genotypes. The chlorophyll values ranged between 12.94 and 20.35 SPAD at irradiation time of 10s and between 17.26 and 20.87 SPAD for irradiation time of 20s. The chlorophyll content values in the control samples ranged between 19.94 and 22.26 SPAD. Experimental investigations of microwave irradiation on plant development may hel...

2-Chloroethylphosphonic acid dialkylesters (bis-(2-chloroethyl), dimethyl, diethyl, dipropyl, dib... more 2-Chloroethylphosphonic acid dialkylesters (bis-(2-chloroethyl), dimethyl, diethyl, dipropyl, dibutyl and dipentylesters) were hydrolyzed in order to obtain 2-chloroethylphosphonic acid, used as a plant growth regulator. Experiments were made in neutral or acid conditions, in order to find optimal conditions for esters hydrolysis. The obtained 2-chloroethylphosphonic acid was tested, regarding its biological activity, on melon, cucumber, blackcurrant and bilberry.

Thermal treatment of cereal grains affects carbohydrate and micronutrient content and bioavailabi... more Thermal treatment of cereal grains affects carbohydrate and micronutrient content and bioavailability. Water-retention capacity (WRC) is an important index for the effects of fiber in the diet and the metabolic activity of fiber along the gut. This study evaluated the effect of thermal treatment and digestive enzymes on wheat and barley WRC. Ground wheat and barley samples were heated for different time periods at 150oC before in vitro gastric and intestinal digestion. WRC values in heat treated wheat and barley are at higher levels as compared to the values of untreated cereals. WRC in barley ranged from 1.026 g water/g DM (untreated) to 1.36 g water/g DM (heated at 150oC for 15 minute). The increase was much lower in heat treated wheat, from 0.973 g water/g DM up to 1.03 g water/g DM at 5 minutes heating time.

Journal of Chromatography A, 2002

Parameters that affect the permeation of analytes across a thin (0.025 mm) flat membrane of polys... more Parameters that affect the permeation of analytes across a thin (0.025 mm) flat membrane of polysiloxane in a membrane and trap interface coupled to a gas chromatograph are examined taking into account a mechanism of mass transport for porous and nonporous materials and the permeation of carrier gas in the direction opposite to that of the analytes. The best permeation rate was reached with hydrogen as carrier gas at a flow-rate between 3 and 5 ml/min, an agitation of analytes outside the membrane above 0.4 m/s and thin membrane. The parameters that affect the residual diffusion time of analytes in membrane were also examined. A practical application of the thin membrane in membrane and trap interface was demonstrated by gas chromatographic monitoring of six volatile organic compounds in air. The limit of detection is at the nmol/ml level depending on the time of trapping and the parameters that affect the permeation through the membrane.

Analytical Chemistry, 2003

Abstract—Protein quality of soybean meal (SBM) is linked to both the reduction of anti-nutritiona... more Abstract—Protein quality of soybean meal (SBM) is linked to both the reduction of anti-nutritional factors (ANFs), and the optimization of protein digestibility. Inadequate heating fails to completely destroy the ANFs. Excessive heating reduces the availability of lysine via the Maillard reaction and possibly, to a lesser extent, other amino acids, and decreases the protein nutritive quality. The objective of the study was the analysis of some chemical indices for determining SBM quality, and their correlation with biophysical indices. The experimental data revealed that urease index (UI) is useful to determine if the soybean meal has been heated enough to reduce ANFs, but it is not useful to determine excessive heat treatment. KOH solubility is a good index for determining over processing, but it is not a sensitive index for monitoring under processing of soybean meal. Combing protein dispersibility index (PDI) and UI could be useful to monitor soybean quality. The investigated bio...

Dietary fibre (DF) includes all non-starch polysaccharides resistant to digestion in the small in... more Dietary fibre (DF) includes all non-starch polysaccharides resistant to digestion in the small intestine and fermentable in the large intestine, and consists of a mixture of components with a varying degree of solubility. Wheat contains substantial amounts of both soluble (SDF) and insoluble (IDF) dietary fibre. The predominant water SDF in wheat is arabinoxylan (6-8%). The main polysaccharide constituents of wheat endosperm cell walls are arabinoxylans, whereas arabinoxylans and β-glucans predominate in wheat aleurone layers, arabinoxylan and cellulose predominate in cell walls of pericarp/testa. Soluble polysaccharides give viscous aqueous solutions. The viscous properties depend on molecular weight and molecule size (linear or branched), ionically charged groups, surrounding structures, and concentration of DF. In aqueous solutions, water molecules penetrate the amorphous regions of soluble DF. The increase in viscosity is explained by formation of Ca 2+ bridges and hydrogen bond...

 Abstract—Cereal grains contain various amounts of non-starch polysaccharides (NSP), which are c... more  Abstract—Cereal grains contain various amounts of non-starch polysaccharides (NSP), which are composed predominantly of arabinoxylans (pentosans), s-glucans and cellulose. The detrimental effect of soluble NSP is mainly associated with the viscous nature of these polysaccharides and their physiological effects on the digestive medium. Experiments were conducted to investigate the influence of some extraction conditions on the viscosity of wheat and barley aqueous extracts. Water extract viscosities (WEV) appeared to be related to the particle size of the meals obtained after grinding. The study shows that viscosities of aqueous extracts of wheat and barley samples have maximum values at 0.5 mm size. The experiments carried out at different extraction temperatures revealed that the optimum temperature for extraction the soluble fraction of NSP is 40°C. At lower temperature (20°C) the extractability of NSP soluble fraction was lower, and at higher temperature (60°C) viscosity increa...

Cereal grains are major sources of dietary fiber (DF), an important component of food and an impo... more Cereal grains are major sources of dietary fiber (DF), an important component of food and an important contributor to human health. Based on their water solubility DF are classified as soluble dietary fiber (SDF) and insoluble dietary fiber (IDF). The physical and physiological properties of dietary fibers are of commercial and nutritional importance. Food processing is mostly based on heating. Heat treatment alters the properties of plant cell wall and modifies the composition and solubility of fibers. The experiments had in view the effect of dry heat treatment (in forced air oven, and microwave oven) on the bioavailability of carbohydrates. The research investigated the dynamics of released glucose (RG) from heat treated whole wheat and barley flour, during in vitro gastric and intestinal digestion. RG after 240 minutes of intestinal digestion revealed a higher digestibility of carbohydrates in wheat samples heated at 150°C for 10 and 15 minutes and in barley samples heated for 5 minutes. When the heating time of the barley samples was longer, the digestibility of carbohydrates decreased due to the formation of higher starch resistant to amylase action. Carbohydrates digestibility of wheat samples exposed to microwaves was lower compared with untreated samples. We observed a moderate increase in carbohydrate digestibility in barley samples after microwave exposure for 30 and 60 seconds. The digestibility decreased after 90 seconds of microwave exposure, due to accelerated Maillard reactions and increase in the proportion of resistant starch.

Changes in particle size, solubility and chemical structure of different fiber components can cau... more Changes in particle size, solubility and chemical structure of different fiber components can cause changes in the bioavailability of some nutrients. Numerous studies have shown a reduction in apparent digestion of proteins in the gastrointestinal tract caused by direct and indirect processes. Endogenous nitrogen losses are due to increased secretion of digestive juices and increased desquamation in the presence of dietary fiber. Food fibers reduce digestion of food and endogenous proteins. Food processing can improve the bioavailability of proteins. Reduction of thermally latent antinutritional factors, such as trypsin inhibitors, phytates and polyphenols, as well as partial denaturation of proteins by heat treatment contributes to their digestibility. Protein quality in processed foods decreases primarily due to reduced lysine bioavailability. Experiments revealed an increase in protein digestibility (PD) in whole wheat flour heated samples in a forced air oven at 150°C over 0-10 ...

The aim of this study was to compare the total protein values obtained in heparin plasma of chick... more The aim of this study was to compare the total protein values obtained in heparin plasma of chickens by a spectrophotometric technique (biuret method), and the values obtained on the same day in the same samples by refractometry. The results obtained by refractometry (average value 2.638±0.153g%) were higher than those obtained by the spectrophotometric method (average value 2.441±0.181g%). There was a low correlation (r = 0.6709) between the total protein values, determined with both methods. Protein is the major determinant of plasma refractive index, but glucose contributes too. The refractometric method is not recommended in chickens for the determination of total protein, because avian blood glucose concentration averages about twice than in mammalian blood.

Different hydration characteristics of dietary fibers are related to their chemical structure. Pr... more Different hydration characteristics of dietary fibers are related to their chemical structure. Processing conditions can modify the physical properties of the fiber matrix and consequently affect their hydration properties. Microwave treatment of cereals and legumes is able to increase the water retention capacity (WRC), which often is required in baked products to make the texture harder and crispy. The present study investigated the effect of microwave radiations on WRC of wheat and barley submitted to in vitro simulated digestion. A slightly higher WRC was observed in treated wheat, from 0.96 g water/g DM (untreated) to 1.015 g water/g DM (treated for 30 s). Greater WRC values were recorded in barley, due to the higher β-glucan content: from 1.026 g water/g DM (untreated) to 1.361 g water/g DM (treated for 30 s).

The presence of microorganisms in milk is of great importance for safety, quality and public heal... more The presence of microorganisms in milk is of great importance for safety, quality and public health. Rapid methods are those that provide results more quickly than the conventional plating methods. Adenosine Tri-Phosphate (ATP) is the most popular biochemical index as it is ubiquitous in cellular life forms and can be detected rapidly using bioluminescence reactions. Electrical conductivity and impedance measurement techniques have proved useful for bacteria counting in commercial applications. During the process of microbial metabolism, large molecules (carbohydrates, fats and proteins) are broken down into smaller and more highly charged components, e.g., fatty acids, amino acids and other organic acids. The highly charged molecules cause a change in the media’s electrical conductivity/resistance. These changes indicate the presence of microorganisms in the original sample. We studied the correlation between the ATP content and the electrical conductivity in raw milk.

Ionized calcium is the physiologically active fraction of serum calcium and therefore its evaluat... more Ionized calcium is the physiologically active fraction of serum calcium and therefore its evaluation is an important clinical parameter both in mammals and birds. In the present study, concentration of total calcium (tCa), ionized calcium (iCa) based on the serum albumin level and on the total protein content, and corrected total calcium (ctCa) based on the serum albumin level were evaluated, and the correlation between these biochemical parameters was investigated in broiler chickens. The average serum iCa was 4.91±0.49g/dL representing 51.76±0.53% from the ctCa. The correlation coefficient between tCa and albumin (r = 0.8608) was greater than that between tCa and total protein (r = 0.7997). Our study illustrated that iCa and ctCa concentrations calculated from tCa and albumin are better indicators of calcium homeostasis than tCa concentrations alone.

Thermal treatment can modify the physicochemical properties of dietary fiber (DF). The study was ... more Thermal treatment can modify the physicochemical properties of dietary fiber (DF). The study was conducted to evaluate the effect of thermal processing on soluble DF fraction of wheat samples subjected to in vitro gastric and intestinal digestion. Samples were treated by heating in a forced air oven at 150oC for 5, 10 and 15 minutes, and by exposing to radiations in a microwaves oven for 30, 60 and 90 seconds. The effect of digestive enzymes action on the soluble DF fraction was evidenced by the variation in the dynamic viscosity (DV) of the supernatant collected after gastric and intestinal incubation. Regardless of the heat treatment, DV increased during processing and during digestion. Maximum DV values were observed at 240 minutes of intestinal digestion, after 90 seconds exposure to microwaves.

Cereals and cereal by-products are the main dietary sources of carbohydrates for humans and anima... more Cereals and cereal by-products are the main dietary sources of carbohydrates for humans and animals. The most common dietary fibers (DF) in cereals are non-starch polysaccharides (NSP). Arabinoxylans and β-glucans are the two most important water-extractable dietary fiber polysaccharides in cereal food products. The structure and molecular weight distributions of these polymers determine their physical properties like viscosity, extractability, solubility and gelling behavior, as well as nutritional properties. Production of cereal foods include processing such as extrusion, flaking, milling and bread making which may have great effects on DF, especially on their molecular weight distributions. Experiments were conducted on some cereals to investigate the water extract viscosity (WEV), the correlation between WEV and NSP, and the influence of processing on the soluble fraction of DF, evidenced by the viscosity of aqueous extracts. The comparison between WEV and the soluble, insoluble and total NSP values, revealed that the WEV are high positively correlated (r = 0.9707) with the soluble NSP content and decrease in the following order: oats>barley>wheat> triticale>corn>rice. Processed cereals have much higher WEV than the unprocessed grains. Viscosities of aqueous extracts vary with fiber content. The flaking process increased the soluble fiber content in wheat, barley and oats, and subsequently the water extract viscosity was also increased. Results revealed a high positive correlation (r = 0.9268) between WEV and DF content of processed wheat, barley and oats. WEV of processed wheat, barley and oats are not correlated with the total carbohydrates content.

Starch is the most important digestible polysaccharide present in foods and feeds. The starch con... more Starch is the most important digestible polysaccharide present in foods and feeds. The starch concentration in cereals cannot be determined directly, because the starch is contained within a structurally and chemically complex matrix. Fine grinding and boiling in dilute HCl are preparative steps necessary for complete release of the starch granules from the protein matrix. Starch can be determined using simple and inexpensive physical methods, such as density, refractive index or optical rotation assessment. The polarimetric method allows the determination even of small starch contents due to its extremely high specific rotation. For more accurate results, the contribution of free sugars is eliminated by dissolution in 40% (V/V) ethanol. The influence of other optically active substances, which might interfere, is removed by filtration/clarification prior to the optical rotation measurement.

The biological availability of nutrients is of great importance in formulating a balanced ration ... more The biological availability of nutrients is of great importance in formulating a balanced ration to attain maximum productivity in animals. In vitro digestibility techniques are useful to provide a quick, inexpensive, and precise prediction of in vivo amino acid and protein digestibility for humans and animals. The objectives of the present study were to determine the in vitro dry matter solubility (DMS) and protein digestibility (PD) of barley grains. Two experiments were conducted: experiment 1 simulated gastric digestion and experiment 2 simulated gastric and small intestinal digestion. DMS in gastric digestion showed an increase with the incubation time. DMS of barley grains ranged in experiment 1 from 0.1067 g/g at 30 minutes digestion time, to 0.1475 g/g at 120 minutes digestion time. Samples showed higher DMS and PD after pepsin-pancreatin digestion than after pepsin digestion. DMS increased with 19.22% and PD increased with 16.18% when pepsin digestion was followed by 240 mi...

The research investigated the dynamics of released glucose from whole wheat flour during in vitro... more The research investigated the dynamics of released glucose from whole wheat flour during in vitro gastric and intestinal digestion. Two experiments were conducted. Experiment 1 (gastric digestion) was an enzymatic hydrolysis with a pepsin solution at pH 2.0 and 37°C for 120 minutes. In experiment 2, first step was followed by the hydrolysis with the multi-enzyme pancreatin (intestinal digestion), at pH 6.8 and 37°C for 4 h. The released glucose (RG) and the refractive index (RI) were determined from the supernatant obtained after centrifugation. Experiments showed an initial increase in the glucose released from 1 g wheat up to 0.472 mg/mL after 1 h of gastric digestion, then followed by decrease. The lowest value was recorded after 2 hours of gastric digestion (0.332 mg/mL). The concentration of the reducing sugars increased throughout the intestinal digestion from 0.549 mg/mL up to 1.990 mg/mL, as a result of starch hydrolysis to dextrins, maltose and then to glucose. The high pos...

The dynamics of released glucose (RG) and refractive index (RI) in the supernatant obtained durin... more The dynamics of released glucose (RG) and refractive index (RI) in the supernatant obtained during in vitro gastric and intestinal digestion of whole barley flour was studied. The in vitro digestion consisted of a two-step enzymatic procedure: (1) initial simulation of gastric digestion using pepsin and (2) simulation of small intestine digestion using multi-enzyme pancreatin. Experiments on 1 g barley flour showed an initial increase in RG concentration up to 0.379 mg / mL at one hour from the onset of gastric digestion, then a decrease in concentration, reaching the lowest value in 2 hours of gastric digestion (0.126 mg/mL). The concentration in reducing sugars increased throughout the intestinal digestion from 0.422 mg/mL up to 2.824 mg/mL, as a result of starch hydrolysis to dextrins, maltose and then to glucose. RI can give information on the amount of glucose released during digestion due to the high positive correlation found between RG and RI (r = 0.761).

Chlorophyll is one of the major components of chloroplasts and represents a variable in assessing... more Chlorophyll is one of the major components of chloroplasts and represents a variable in assessing the physiological status and photosynthetic performance of plants. The purpose of the study was to evaluate the microwave irradiation effect on the chlorophyll content of Hordeum vulgare L. The chlorophyll content was determined at 14 days after the irradiation treatment, using the portable chlorophyll meter SPAD- 502 (Konica Minolta). We observed variations in the chlorophyll content when applying different power values of the radiations and different times of exposure. The chlorophyll content was lower for 720W irradiation power than for 400W, for all studied genotypes. The chlorophyll values ranged between 12.94 and 20.35 SPAD at irradiation time of 10s and between 17.26 and 20.87 SPAD for irradiation time of 20s. The chlorophyll content values in the control samples ranged between 19.94 and 22.26 SPAD. Experimental investigations of microwave irradiation on plant development may hel...

2-Chloroethylphosphonic acid dialkylesters (bis-(2-chloroethyl), dimethyl, diethyl, dipropyl, dib... more 2-Chloroethylphosphonic acid dialkylesters (bis-(2-chloroethyl), dimethyl, diethyl, dipropyl, dibutyl and dipentylesters) were hydrolyzed in order to obtain 2-chloroethylphosphonic acid, used as a plant growth regulator. Experiments were made in neutral or acid conditions, in order to find optimal conditions for esters hydrolysis. The obtained 2-chloroethylphosphonic acid was tested, regarding its biological activity, on melon, cucumber, blackcurrant and bilberry.

Thermal treatment of cereal grains affects carbohydrate and micronutrient content and bioavailabi... more Thermal treatment of cereal grains affects carbohydrate and micronutrient content and bioavailability. Water-retention capacity (WRC) is an important index for the effects of fiber in the diet and the metabolic activity of fiber along the gut. This study evaluated the effect of thermal treatment and digestive enzymes on wheat and barley WRC. Ground wheat and barley samples were heated for different time periods at 150oC before in vitro gastric and intestinal digestion. WRC values in heat treated wheat and barley are at higher levels as compared to the values of untreated cereals. WRC in barley ranged from 1.026 g water/g DM (untreated) to 1.36 g water/g DM (heated at 150oC for 15 minute). The increase was much lower in heat treated wheat, from 0.973 g water/g DM up to 1.03 g water/g DM at 5 minutes heating time.

Journal of Chromatography A, 2002

Parameters that affect the permeation of analytes across a thin (0.025 mm) flat membrane of polys... more Parameters that affect the permeation of analytes across a thin (0.025 mm) flat membrane of polysiloxane in a membrane and trap interface coupled to a gas chromatograph are examined taking into account a mechanism of mass transport for porous and nonporous materials and the permeation of carrier gas in the direction opposite to that of the analytes. The best permeation rate was reached with hydrogen as carrier gas at a flow-rate between 3 and 5 ml/min, an agitation of analytes outside the membrane above 0.4 m/s and thin membrane. The parameters that affect the residual diffusion time of analytes in membrane were also examined. A practical application of the thin membrane in membrane and trap interface was demonstrated by gas chromatographic monitoring of six volatile organic compounds in air. The limit of detection is at the nmol/ml level depending on the time of trapping and the parameters that affect the permeation through the membrane.

Analytical Chemistry, 2003