Mathematical modeling of airflow and heat transfer during forced convection cooling of produce considering various package vent areas

The influence of different package vent configurations, including ventilated packages with 1, 3 and 5 vents, on produce temperature distribution during forced convection cooling of produce was investigated by mathematical modeling of simultaneous airflow and heat transfer. Generally, produce cooling uniformity was increased by increasing the number of vents from 1 to 5. Produce cooling heterogeneity increased until about 90 min cooling and subsequently decreased with further cooling in all 3 ventilated packages. The methodology developed in this study can be used as a design tool to provide homogeneous temperature distribution in ventilated packages during forced convection cooling of produce.     

Vicinal support vector classifier: A novel approach for robust classification based on SKDA

In this paper, we present a detailed study and comparison of different classification algorithms. Our main purpose is the study of the Vicinal Support Vector Classifier (VSVC) and its relations to the other state-of-the-art classifiers. To this end, we start by the historical development of each classifier, derivation of the mathematics behind it and describing the relations that exist between some of them, in particular the relation between the VSVC and the other classifiers. Thereafter, we apply them to two famous learning datasets very used by the research community, namely the MIT-CBCL face and the Wisconsin Diagnostic Breast Cancer (WDBC) datasets. We show that despite its simplicity compared to the other state-of-the-art classifiers, the VSVC leads to very robust classification results and provide some practical advantages compared to the other classifiers.     

Inactivation of Escherichia coli O157:H7 and Salmonella enteritidis in Liquid Egg White Using Pulsed Electric Field

ABSTRACT: The effects of temperature and pulsed electric field (PEF) intensity on inactivation of pathogens such as Escherichia coli O157:H7 and Salmonella enteritidis in egg white was investigated. Liquid egg white inoculated with 10⁸ colony-forming units (CFU)/mL of each pathogen was treated with up to 60 pulses (each of 2 JAS width) at electric field intensities of 20 and 30 kV/cm. The processing temperatures were 10°C, 20°C, and 30°C. After treatment, uninjured and total viable cells were enumerated in selective and nonselective agars, respectively. Maximum inactivations of 3.7 and 2.9 log units were obtained for S. enteritidis and E. coli O157:H7, respectively, while injured cells accounted for 0.5 and 0.9 logs for E. coli O157:H7 and S. enteritidis , respectively. For both bacteria, increasing treatment temperature tended to increase the inactivation rate. There was synergy between electric field intensity and processing temperature. The inactivation rate constant k _T values for E. coli O157:H7 on both selective and nonselective agars were 8.2 × 10^-3 and 6.6 × 10^-3/μS, whereas the values for S. enteritidis were 16.2 × 10^-3 and 12.6 × 10^-3/μS, respectively. The results suggest that E. coli O157:H7 was more resistant to heat-PEF treatment compared with S. enteritidis.     

Inter-particle space fractions in fried batter coatings as influenced by batter formulation and pre-drying time

Evaluation different fractions of the spaces in a fried product that are occupied by air, moisture, or fat provides useful information for researcher and manufacturer to better understand the mechanism of oil absorption during frying. The objective of this study was to determine the influence of batter formulations and pre-drying on the fraction of inter-particle spaces in batter coating. Pre-drying decreased the amount of fat to 2.97 g/100 g compared to non-pre-dried samples which showed 4.37 g/100 g fat content. Higher rice flour content in batter significantly increased the fraction of inter-particle spaces occupied by air (SOA), and decreased the fraction of spaces occupied by moisture (SOM) and fat (SOF). Longer pre-drying times showed greater fraction of spaces occupied by air, and smaller fraction of spaces occupied by moisture and fat. SOA, SOM, and SOF of the batter systems ranged from 2.2% to 46.03%, 2.55 to 47.07%, and 0.35% to 11.11%, respectively. Using higher amount of wheat flour in batter and longer pre-drying time showed to significantly decrease fat uptake during frying.     

Electrohydrodynamic Drying—A Concise Overview

Electrohydrodynamic (EHD) drying is a novel method of non-thermal processing. The drying can be carried out using either AC or DC high voltages. The thermodynamic considerations regarding the lowering of temperature under EHD drying include rapid rates of evaporation and exothermic interaction of the electric field with a dielectric material. Multi-point and plate electrode systems are efficient in accelerating drying of agricultural materials. Compared to hot air (convective) drying systems, EHD drying systems offer lower food production costs along with superior quality in terms of physiochemical properties such as color, shrinkage, flavor, and nutrient content. Compared to convective and freeze-drying, EHD drying systems, given their simpler design and lesser energy consumption, show great potential for bulk and industrial drying applications.     

Pore development in chicken meat during deep-fat frying

In this study, the effect frying oil temperature (FOT) and frying time on pore development was investigated during deep-fat frying (DFF) of chicken breast meat. The samples were sized to the following dimension: length×width×thickness=20×15×10 mm, and were fried at different FOTs (170°C, 180°C, and 190°C) in an industrial fryer for periods varying from 5 to 900 s. Oil uptake analysis was conducted by soxhlet extraction method with petroleum ether as the base extraction solvent. Pore development computation was based on the densities (bulk and apparent) measured after the end of each frying time with a fluid displacement pycnometry. The process variables significantly (P<0.01) influenced pore development in chicken meat during DFF. The final oil uptake was found to have influenced pore development. A goodness-of-fit test suggest linear model fitted well to the pore development and moisture loss experimental data while exponential model gave the best fit for pore development and oil uptake in chicken meat. A porosity of 0.28, 0.24 and 0.22 were found at FOT (170°C, 180°C, and 190°C), respectively.     

Proteolysis of Cheese Slurry Made from Pulsed Electric Field-Treated Milk

Raw milk cheeses have unique flavor and texture characteristics not obtainable in cheeses made from pasteurized milk. However, cheeses made from pasteurized milk are widespread, primarily for public health reasons. Pulsed electric field (PEF) treatment as a non-thermal pasteurization method has shown its ability to keep the flavor and natural characteristics of food samples intact, thus providing advantage over conventional heat processing. In this study, PEF treatment was performed in a continuous treatment chamber, consisting of two parallel stainless steel electrodes separated by a 50-mm-thick insulator. A 30-kV pulse generator was used to deliver bi-polar square waveform electric field to milk sample. Pulse width was 2 μs; pulse frequency was 2 Hz, and up to 120 pulses were applied. Cheese curds were made from raw milk, pasteurized milk, and PEF-treated milk, and their proteolysis processes were compared using curd slurry incubated at 30 °C for 5 days. The profiles of water-soluble peptides were measured using an reversed-phase high-performance liquid chromatography (RP-HPLC) system. The concentration of free amino acids was measured by Cd–ninhydrin method. Results indicated that PEF-treated milk has intermediate proteolysis profiles between raw milk and pasteurized milk in terms of peptide and free amino acid concentration. The results showed the potential of making high-quality cheeses by PEF treatment without sacrificing the natural characteristics of the cheeses.     

From pollutant to solution of wastewater pollution: Synthesis of activated carbon from textile sludge for dye adsorption

Adsorption is an important process in wastewater treatment,and conversion of waste materials to adsorbent offers a solution to high material cost related to the use of commercial activated carbon.This study investigated the adsorption behaviour of Reactive Black 5(RB5)and methylene blue(MB)onto activated carbon produced from textile sludge(TSAC).The activated carbon was synthesized through chemical activation of precursor followed with carbonization at 650°C under nitrogen flow.Effects of time(0–200 min),pH(2–10),temperature(25–60°C),initial dye concentration(0–200 mg·L~(-1)),and adsorbent dosage(0.01–0.15 g)on dye removal efficiency were investigated.Preliminary screening revealed that TSAC synthesized via H_2SO_4activation showed higher adsorption behaviour than TSAC activated by KCl and ZnCl_2.The adsorption capacity of TSAC was found to be 11.98 mg·g~(-1)(RB5)and 13.27 mg·g~(-1)(MB),and is dependent on adsorption time and initial dye concentration.The adsorption data for both dyes were well fitted to Freundlich isotherm model which explains the heterogeneous nature of TSAC surface.The dye adsorption obeyed pseudo-second order kinetic model,thus chemisorption was the controlling step.This study reveals potential of textile sludge in removal of dyes from aqueous solution,and further studies are required to establish the applicability of the synthesized adsorbent for the treatment of waste water containing toxic dyes from textile industry.     

Effects of methylcellulose,xanthan gum and carboxymethylcellulose on thermal properties of batter systems formulated with different flour combinations

The functionalities of hydrocolloid–flour mixtures in terms of the thermal properties of their resulting batter systems were investigated, and the effects of different thermal processes such as cooking–freezing–thawing (CFT) and freezing–cooking (FC) on thermal properties of the various batter systems were determined in this study. Differential scanning calorimetry (DSC) was used to determine thermal property parameters including gelatinization temperature (T_G), total enthalpies of gelatinization (ΔH_G), glass transition temperature (T_g), melting peak temperature (T_m), and total melting enthalpies (ΔH_m). The different thermal processes did not significantly affect either T_G or ΔH_G of batter systems, but they influenced the glass transition behavior and the ΔH_m of batter systems. The thermal processes also showed different effects on the batter systems containing different hydrocolloids such as methylcellulose (MC), carboxymethylcellulose (CMC), and xanthan gum (XG). The hydrocolloids shifted T_G upwards, depressed T_g, and increased T_m of batters. The effect of these hydrocolloids on glass transition temperature was more pronounced in raw samples (FC process) than in cooked samples and increased with increasing levels of CMC and MC used in the formulations. Batters with MC showed increased ΔH_m for all the thermal processes. CMC only showed significant effect on ΔH_m for cooked samples (CFT process). MC and CMC showed more pronounced effects on T_g for raw uncooked rice- and corn flour-based batters than on raw uncooked wheat flour-based batters. However, this special effect was not obvious in the batters containing 0.2% XG.