scholarly journals Relative Stability of Selenites and Selenates in Feed Premixes as a Function of Water Activity

2007 ◽  
Vol 90 (2) ◽  
pp. 349-353 ◽  
Author(s):  
Sylvan Eisenberg
Keyword(s):  
Ascorbic Acid ◽  
Moisture Content ◽  
Water Activity ◽  
Filter Paper ◽  
Sodium Selenite ◽  
High Water ◽  
Sodium Selenate ◽  
Elemental Selenium ◽  
The Subject ◽  
Vapor Analysis

Abstract Sodium selenite is more hygroscopic than sodium selenate. It is, therefore, more likely to dissolve when dispersed in feeds of relatively high water activity. When dissolved, it may form selenious acid and disperse as a vapor. This is easily demonstrated by mounting a filter paper wetted with a reagent such as ascorbic acid over the subject feed, but not in contact with it. The paper turns brown as elemental selenium is formed from reduction of the vapor. Analysis of the paper ensures that the brown is indeed selenium. Though premixes are generally low enough in moisture content to ensure stability of the selenites, this is not true of many feeds. The water activities of a number of feeds, feed premixes, and feed ingredients have been determined instrumentally and compared to those of saturated solutions of sodium selenite and sodium selenate. There is no question that the selenite often dissolves with the potential to react and, in so doing, loses its nutritional function.

scholarly journals Drying kinetics and physical and chemical characterization of white-fleshed ‘pitaya’ peels

2017 ◽  
Vol 21 (12) ◽  
pp. 872-877 ◽  
Author(s):  
Francislaine S. dos Santos ◽  
Rossana M. F. de Figueirêdo ◽  
Alexandre J. de M. Queiroz ◽  
Dyego da C. Santos
Keyword(s):  
Experimental Data ◽  
Ascorbic Acid ◽  
Moisture Content ◽  
Water Activity ◽  
Reducing Sugars ◽  
Drying Kinetics ◽  
Coefficient Of Determination ◽  
Mean Square ◽  
Mean Square Deviation ◽  
Physical And Chemical

ABSTRACT The objective of this work was to obtain the drying kinetic curves of white-fleshed ‘pitaya’ peels and characterize the obtained powder regarding physical and chemical parameters. Different mathematical models were fitted to the experimental data of drying kinetics, considering the coefficient of determination (R2), mean square deviation (MSD) and residual distribution as fit criteria. The peels had an initial moisture content of 93.38% (w.b.) and final moisture contents of 5.39% at temperature of 50 °C, 5.27% at 60 °C and 4.40% at 70 °C. After drying, the peels were disintegrated to obtain the powders and characterized for moisture content, reducing sugars, total titratable acidity, ascorbic acid, betacyanins, betaxanthins, water activity and color, in order to evaluate the influence of temperature on the quality of powders. The Page model was the one that best fitted to the experimental data, presenting coefficient of determination higher than 0.998, mean square deviation lower than 0.02 and random distribution of residuals. Increment in drying air temperature promoted increase of pH, ascorbic acid, luminosity and yellowness, and reduction of moisture content, reducing sugars, acidity, betacyanins, betaxanthins, water activity and redness. Considering the retention of betalains, the drying temperature of 50 °C is the most suitable for the production and use of ‘pitaya’ peel powder.

scholarly journals Effect of drying air condition and feed composition on the properties of orange juice spray dried powder

2018 ◽  
Vol 192 ◽  
pp. 03013 ◽  
Author(s):  
Kankanit Khwanpruk ◽  
Chanida Akkaraphenphan ◽  
Patipan Wattananukit ◽  
Worakarn Kaewket ◽  
Suttiphat Chusai
Keyword(s):  
Ascorbic Acid ◽  
Moisture Content ◽  
Water Activity ◽  
Acid Content ◽  
Orange Juice ◽  
Ascorbic Acid Content ◽  
Product Yield ◽  
Feed Composition ◽  
Dry Air ◽  
Spray Dried

This research aims to investigate the effect of inlet air humidity, drying temperature and feed composition on the properties of orange juice spray dried powder. Maltodextrin (DE10-12) was used as carrier material. Full factorial design was applied to this research. Inlet air with humidity of 10 g/kg dry air and 20 g/kg dry air, inlet drying air temperature of 140°C 160°C and 180°C and feed concentration of 40°Brix which varied the weight ratio of orange juice solid content to maltodextrin of 1:3 and 1:4.5 were examined. All spray drying conditions were performed in replicate. Ascorbic acid, moisture content water activity, pH and product yield were analysed. Analysis of variance revealed that humidity of inlet air influenced significantly on product yield, moisture content, water activity. Besides, the quality of product in term of ascorbic acid content was affected significantly by drying temperature and fraction of maltodextrin. Higher drying temperatures lead to lesser of ascorbic acid content and the more fraction of maltodextrin used in feed, the more ascorbic acid content retained in product.

scholarly journals Effect of Addition of Green Coffee Parchment on Structural, Qualitative and Chemical Properties of Gluten-Free Bread

Foods ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 5
Author(s):  
Paola Littardi ◽  
Massimiliano Rinaldi ◽  
Maria Grimaldi ◽  
Antonella Cavazza ◽  
Emma Chiavaro
Keyword(s):  
Moisture Content ◽  
Oxidative Stability ◽  
Water Activity ◽  
Chemical Properties ◽  
Antioxidant Compounds ◽  
Total Phenol Content ◽  
Green Coffee ◽  
Gluten Free ◽  
Wet Processing ◽  
Total Antioxidant

Green coffee parchment (GCP) is becoming interesting, due to the diffusion of wet processing in which coffee parchment is collected separately; it is one of the less studied coffee by-products, but it is reported to be rich in phenolic compounds and dietary fiber. The addition of GCP (355–500 μm) at 2 % to gluten-free breads was investigated in terms of physical properties (volume, moisture content, water activity, crumb grain, texture, and color), total antioxidant capacity (TAC) and total phenol content during three days of storage. Moreover, the effects of GCP on sensorial characteristics, 5-hydroxymethylfurfural (HMF), and oxidative stability was evaluated. From the sensorial analysis, bread with 2% addition resulted in being acceptable for consumers with no significant differences from the control, while 4% of GCP was discarded by consumers, as it resulted in being too bitter. Moreover, GCP at 2% addition did not modify volume, moisture content, and water activity. On the contrary, GCP deeply affected the color with a darker aspect that was appreciated by consumers. Regarding texture, 2% of GCP did not affect hardness, cohesiveness, and staling process during storage. Interestingly, 2% of GCP significantly improved the TAC and oxidative stability of the bread; in accordance with these results, 2% of GCP reduced the HMF content, thanks to its antioxidant compounds.

Comparative effects of nano elemental selenium and sodium selenite on selenium retention in broiler chickens

2012 ◽  
Vol 177 (3-4) ◽  
pp. 204-210 ◽  
Author(s):  
C.H. Hu ◽  
Y.L. Li ◽  
L. Xiong ◽  
H.M. Zhang ◽  
J. Song ◽  
...  
Keyword(s):  
Broiler Chickens ◽  
Sodium Selenite ◽  
Elemental Selenium

Moisture migration in a cereal composite food at high water activity: Effects of initial porosity and fat content

2006 ◽  
Vol 43 (2) ◽  
pp. 144-151 ◽  
Author(s):  
Elisabeth Roca ◽  
Valérie Guillard ◽  
Stéphane Guilbert ◽  
Nathalie Gontard
Keyword(s):  
Water Activity ◽  
High Water ◽  
Fat Content ◽  
Initial Porosity ◽  
Moisture Migration

Microwave Nondestructive Sensing of Moisture Content and Water Activity of Almonds

2021 ◽  
Vol 64 (4) ◽  
pp. 1373-1379
Author(s):  
Samir Trabelsi
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Moisture Content ◽  
Bulk Density ◽  
Water Activity ◽  
Free Space ◽  
Loss Factor ◽  
Dielectric Loss Factor ◽  
List Type

HighlightsMoisture and water activity were determined nondestructively and in real time from measurement of dielectric properties.Moisture and water activity calibration equations were established in terms of the dielectric properties.Situations in which bulk density was known or unknown were considered.SEC ranged from 0.41% to 0.68% for moisture and from 0.02 to 0.04 for water activity.Abstract. A method for rapid and nondestructive determination of moisture content and water activity of granular and particulate materials was developed. The method relies on measurement of the dielectric constant and dielectric loss factor at a single microwave frequency. For the purpose of illustration, the method was applied to predicting the moisture content and water activity of almond kernels. A free-space transmission technique was used for accurate measurement of the dielectric properties. Samples of Bute Padre almond kernels with moisture content ranging from 4.8% to 16.5%, wet basis (w.b.), and water activity ranging from 0.50 to 0.93 were loaded into a Styrofoam sample holder and placed between two horn-lens antennas connected to a vector network analyzer. The dielectric properties were calculated from measurement of the attenuation and phase shift at 8 GHz and 25°C. The dielectric properties increased linearly with moisture content, while they showed an exponential increase with water activity. Situations in which the bulk density was known and unknown were considered. Linear and exponential growth regressions provided equations correlating the dielectric properties with moisture content and water activity with coefficients of determination (r2) higher than 0.96. Analytical expressions of moisture content and water activity in terms of the dielectric properties measured at 8 GHz and 25°C are provided. The standard error of calibration (SEC) was calculated for each calibration equation. Results show that moisture content can be predicted with SECs ranging from 0.41% to 0.68% (w.b.) and water activity with SECs ranging from 0.02 to 0.04 for almond kernel samples with water activity ranging from 0.5 to 0.9 and moisture contents ranging from 4.8% to 16.5% (w.b.). Keywords: Bulk density, Dielectric constant, Dielectric loss factor, Free-space measurements, Loss tangent, Microwave frequencies, Moisture content, Water activity.

scholarly journals CURVAS DE SECAGEM E AVALIAÇÃO DA ATIVIDADE DE ÁGUA DA BANANA PASSA

2004 ◽  
Vol 22 (1) ◽  
Author(s):  
MILTON CANO-CHAUCA ◽  
AFONSO M. RAMOS ◽  
PAULO C. STRINGHETA ◽  
JOSÉ ANTONIO MARQUES ◽  
POLLYANNA IBRAHIM SILVA
Keyword(s):  
Experimental Data ◽  
Linear Regression ◽  
Moisture Content ◽  
Water Activity ◽  
Linear Regression Analysis ◽  
Sorption Isotherms ◽  
Exponential Model ◽  
Drying Time ◽  
Non Linear ◽  
Drying Curves

Curvas de secagem de banana passa foram determinadas, utilizando-se três temperaturas do ar de secagem. Os resultados indicaram que para reduzir o teor de umidade do produto até 23,5% foram necessários tempos de secagem de 51, 36 e 30 horas paras as temperaturas de 50, 60 e 70ºC, respectivamente. O modelo exponencial U/Uo = exp(-kt) foi ajustado para os dados experimentais mediante análise de regressão não-linear, encontrandose alto coeficiente de regressão linear. Determinou-se a atividade de água do produto ao longo do processo de secagem para as três temperaturas testadas. Estudou-se a correlação entre a atividade de água e o teor de umidade do produto, determinando-se as isotermas de dessorção da banana passa a 25ºC. Observou-se que a atividade de água diminuiu em função do tempo de secagem e do teor de umidade para as três temperaturas de secagem. Os dados experimentais foram ajustados mediante regressão não-linear ao modelo polinomial e a seguinte equação foi obtida: U = -1844,93 + 7293,53Aa – 9515,52Aa2 + 4157,196Aa3. O ajuste mostrou-se satisfatório (R2 > 0,90). DRYING CURVES AND WATER ACTIVITY EVALUATION OF THE BANANA-PASSES Abstract Banana drying curves were determined by utilizing three drying air temperatures. The results indicated that to reduce the moisture content of the product until 23.5% it were necessary drying times of 51, 36 and 30 hours for temperatures of 50, 60 and 70ºC, respectively. The exponential model U/Uo = exp(-kt) was adjusted for the experimental data by means of non linear regression analysis, and a high coefficient of linear regression was found. The water activity of the product was determined throughout the drying process for the three tested temperatures. The correlation between the water activity and moisture content of the product was studied, and the sorption isotherms were determined at 25º C. It was observed that the water activity decreased in function to the drying time and moisture content for the three drying temperatures. The experimental data were adjusted by means of non linear regression to the polynomial model and the following equation was obtained: U = - 1844.93 + 7293.53A a – 9515.52 Aa 2 + 4157.196A a 3. The final adjust was satisfactory (R2 > 0.90).

Occurrence of Toxigenic Molds in Brazilian Cheese

1992 ◽  
Vol 55 (3) ◽  
pp. 187-191 ◽  
Author(s):  
MARTA HIROMI TANIWAKI ◽  
ARIENE GIMENES FERNANDES VAN DENDER
Keyword(s):  
Water Activity ◽  
High Water ◽  
Penicillium Species ◽  
High Carbohydrate ◽  
Different Types ◽  
Carbohydrate Contents

Several samples of cheese obtained from regular retailers in Campinas, Brazil, were examined for molds and mycotoxins. Strains of Aspergillus and Penicillium were isolated and evaluated for their potential for producing toxins. Two of the isolated Penicillium species produced citrinin, while another produced patulin. However, no mycotoxins were detected in any of the cheese samples tested. Experiments with different types of cheese and a semisynthetic cheese were carried out in order to verify production of citrinin and patulin. It was observed that citrinin may be produced in cheese with high water activity and in semisynthetic cheese. However, patulin does not appear to be stable in cheese, even in semisynthetic cheese with high water activity and high carbohydrate contents.

scholarly journals Sorption isotherms of Brazil nuts

2019 ◽  
Vol 23 (10) ◽  
pp. 776-781 ◽  
Author(s):  
Fernando M. Botelho ◽  
Nilso J. Boschiroli Neto ◽  
Silvia de C. C. Botelho ◽  
Gabriel H. H. de Oliveira ◽  
Michele R. Hauth
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Water Activity ◽  
Sorption Isotherms ◽  
Static Method ◽  
Acid Solutions ◽  
Brazil Nut ◽  
Brazil Nuts ◽  
Abstract Knowledge ◽  
Sorption Phenomenon

ABSTRACT Knowledge of the water sorption phenomenon in Brazil nut seeds will allow proper handling of this product, especially with regard to adequate conditions for safe storage. Thus, the present study aimed to determine the sorption isotherms (desorption and adsorption) of Brazil nuts, fitting different mathematical models to the experimental data, as well as to examine the hysteresis effect. To obtain the sorption isotherms, the static method was employed at temperatures of 25, 35, 45 and 55 °C and air relative humidities varying from 10 to 80%. The psychrometric conditions of the air were acquired with the aid of acid solutions and specific saturated saline left inside desiccators with the samples. It was verified that for a given isotherm, the equilibrium moisture content of Brazil nuts increases with water activity increment. In addition, at a constant water activity, equilibrium moisture content decreases with temperature increase. The Copace, Henderson and Oswin are the models that best describe the hygroscopicity of the Brazil nut seed for both the adsorption and desorption processes. Hysteresis was more pronounced at lower temperatures and higher values of water activity. The moisture content value for storage at temperatures less than 55 °C, without the risk of fungal development, must be lower than 8.2% (d.b.).

Sign in / Sign up

Export Citation Format

Share Document