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.     

Mapping of Fat and Moisture Distribution in Atlantic Salmon Using Near-Infrared Hyperspectral Imaging

A nondestructive and rapid method using near-infrared (NIR) hyperspectral imaging was investigated to determine the spatial distribution of fat and moisture in Atlantic salmon fillets. Altogether, 100 samples were studied, cutting out from different parts of five whole fillets. For each sample, the hyperspectral image was collected with a pushbroom NIR (899–1,694 nm) hyperspectral imaging system followed by chemical analysis to measure its reference fat and moisture contents. Mean spectrum were extracted from the region of interest inside each hyperspectral image. The quantitative relationships between spectral data and the reference chemical values were successfully developed based on partial least squares (PLS) regression with correlation coefficient of prediction of 0.93 and 0.94, and root mean square error of prediction of 1.24 and 1.06 for fat and moisture, respectively. Then the PLS models were applied pixel-wise to the hyperspectral images of the prediction samples to produce chemical images for visualizing fat and moisture distribution. The results were promising and demonstrated the potential of this technique to predict constituent distribution in salmon fillets.     

Detecting Fertility and Early Embryo Development of Chicken Eggs Using Near-Infrared Hyperspectral Imaging

Early detection of infertile and non-hatchable eggs would benefit hatcheries and poultry breeding farms by saving space, handling costs, and preventing contamination from exploder eggs. Therefore, it would be advantageous to the hatchery industry of developing a non-destructive, rapid, and accurate method to detect the fertility and embryo development of eggs. For this purpose, a near-infrared hyperspectral imaging system was developed to detect fertility and early embryo development. A total of 174 white-shell chicken eggs including 156 fertile eggs and 18 infertile eggs were used in this study and all eggs were incubated in a commercial incubator for 4 days. Hyperspectral images were captured for all eggs on each day of incubation. After imaging on each day, developing embryos in randomly selected eggs were stopped by injecting sodium azide (NaN₃). All the eggs were divided into two classes, fertile eggs and non-fertile eggs (including infertile eggs and dead embryos), and the data set of each class varied with day of incubation. The region of interest (ROI) of each hyperspectral image was segmented and the image texture information was extracted from the ROI of spectral images using Gabor filters. Two types of spectral transmission characteristics termed MS and MG, were obtained by averaging the spectral information of ROI and Gabor-filtered ROI, respectively. The dimensionality of the spectral transmission characteristics were reduced by PCA. The first three PCs were used for K-means clustering, as well as the first three bands with maximum responses of each spectral transmission characteristic. The best classification results were 100 % at day 0, 78.8 % at day 1, 74.1 % at day 2, 81.8 % at day 3, and 84.1 % at day 4. A perfect detection of fertility prior to incubation was obtained using only the first three bands of maximum responses of MS. The classification results suggested the usefulness of the image texture information for detection of early embryo development. Promising results were also obtained when only the first three bands with maximum response of spectral transmission characteristics were used, which indicated the potential in applying hyperspectral imaging techniques to develop a real-time system for detecting fertility and early embryo development of chicken eggs.     

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.     

Protein Structural Changes During Preparation and Storage of Surimi

The changes in protein structure associated with the preparation and frozen storage of surimi were investigated. Raw surimi was prepared by repeatedly washing Alaska pollock flesh with chilled water. The product was either slowly frozen or underwent rapid freezing using liquid air; in either case it was then subjected to frozen storage at ‐20 °C for 24 mo. Fourier transform infrared/attenuated total reflectance (FTIR/ATR) spectroscopy showed that during preparation of surimi, the a‐helix content increased with increased number of washing cycles. Differential scanning calorimetry (DSC) revealed a shift in the thermal transition of actin to a higher temperature during surimi preparation. Electrophoresis, FTIR/ATR spectroscopy, and DSC results revealed a loss of myofibrillar proteins from surimi after 3 washing cycles, suggesting that 3 washing cycles were adequate to prepare surimi. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) showed relatively minor changes in protein subunit structure with some loss of the myosin light chains (MLC); myosin heavy chain (MHC), actin, and tropomyosin were found to be relatively stable. Native‐PAGE showed no major changes in surimi after 24 mo storage at ‐20 °C. FTIR/ ATR spectroscopy indicated a significant decrease in a‐helix relative to p‐sheet structure in surimi after 2 y of storage at ‐20 °C. The loss of α‐helical content was more significant in slowly frozen surimi compared with rapid‐frozen surimi samples. DSC results revealed a shift in the thermal transition of actin to lower temperatures during frozen storage of surimi.     

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.     

Predicting intramuscular fat content and marbling score of pork along the longissimus muscle based on the last rib

The possibility of using IMF content/MS at the last rib to predict the corresponding fat attribute of loin chops at the 2nd last to the 7th last thoracic ribs and the mean of IMF content/MS of the whole loin joint was investigated. Linear and quadratic regression, cross‐validation analysis and analysis of variance were employed for the study. For either IMF or MS, linear and quadratic regression models had similar performance. The best mean correlation coefficients of calibration (R_c) of 0.91 and cross‐validation (R_v) of 0.88 were obtained for linear regression model of IMF content of the whole loin, while R_c of 0.90 and R_v of 0.88 were obtained for quadratic regression model of MS of the whole loin. The results indicated that IMF content and MS at the last rib had great potential for the prediction of IMF content and MS at the other ribs.     

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.     

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.