A micromechanical based finite element model approach to accurately predict the effective thermal properties of micro-aerated chocolate

Micro-aeration is a method to modify the sensorial attributes of chocolate but also affects the material properties of chocolate, which in turn, determine its material response during manufacturing and oral processes. This study aims to define the effect of micro-aeration on the thermal properties of chocolate by considering the changes of chocolate microstructure due to micro-aeration. Micro-aeration was found to alter the chocolate microstructure creating a layer of a third phase at the porous interfaces, which is argued to consist of cocoa butter of higher melting properties. A multiscale Finite Element Model is developed, which was confirmed by macroscale heat transfer measurements, to parametrically simulate the structural changes of micro-porous chocolates at the microscale level and estimate their effective properties, such as thermal conductivity and specific heat capacity. The developed multiscale computational model simulates the porous chocolate as a two-phase (chocolate- pores) or three-phase material (chocolate-cocoa butter layer- pores). The investigation identified a new, complex transient thermal mechanism that controls the behaviour of micro-aerated chocolate during melting and solidification. The results showed a maximum 13% reduction of k_eff and 15% increase of C_peff with 15% micro-aeration resulting to a slower transient heat transfer through the micro-aerated chocolate. The reason is that the micro-aerated chocolate can store a larger amount of thermal energy than its solid counterpart. This effect slows down the transient heat transfer rate in the chocolate and modifies melting/solidification rate and impacts sensorial attributes during oral processing and cooling during manufacturing.     

Rheological characterizations of texturized whey protein concentrate-based powders produced by reactive supercritical fluid extrusion

A powder blend comprising (by weight) 94% whey protein concentrate (WPC80), 6% pre-gelatinized corn starch, 0.6% CaCl₂, and 0.6% NaCl was texturized using a supercritical fluid extrusion (SCFX) process. The blend was extruded at 90 °C in a pH range of 2.89 to 8.16 with 1% (db) supercritical carbon dioxide (SC-CO₂) and 60% moisture content. The texturized WPC-based (TWPC) samples were dried, grounded into powder, reconstituted in water, and evaluated using a range of rheological studies. Most TWPC samples exhibited shear thinning behavior and their mechanical spectra were typical of weak gel characteristics. The TWPC produced under extremely acidic condition of pH 2.89 with SC-CO₂ yielded the highest η^* (10,049 Pa s) and G′ (9,885 Pa) compared to the unprocessed WPC (η^* = 0.083 Pa s and G’ = 0.036 Pa). The SCFX process rendered WPC into a product with cold-setting gel characteristics that may be suitable for use as a food texturizer over a wide range of temperatures.     

DISTRIBUTION of HEAT TRANSFER RATE and LETHALITY IN A SINGLE BASKET WATER CASCADE RETORT

Temperature and heat distribution studies were carried out in a single basket horizontal water cascading retort at two temperatures and two air over-pressure levels under fully loaded operating conditions. Various heat transfer parameters (heating and cooling rate indices, f_h and f_c), lag factors (j_ch and j_cc) and process lethality (F_o) were used as indicators of the retort performance. Time-temperature data gathered from 24 Lexan^TM transducers were used for calculation of the heating and cooling rate indices as well as lethality. There were significant variations in the temperature distribution and heat transfer parameters at the different tray levels; however, these variations did not contribute to large variations in the accumulated overall process lethality.     

Thermal inactivation of Salmonella spp. during conching

Although chocolate is a microbiologically stable product it has been described as a vehicle for Salmonella spp. Because of the low water activity (a_w) and the high fat content of chocolate Salmonella spp. shows an increased heat resistance, even during the thermal process of chocolate making. The aim of this study was to evaluate the thermal inactivation of Salmonella spp. during conching in various masses of chocolate and cocoa butter at different temperatures (50-90 °C). The effect of thermal treatment on Salmonella spp. was determined with the MPN (Most-Probable-Number) method. Results of thermal treatment showed approximate D-values for cocoa butter from D_50°C = 245 min to D_60°C = 306 min, for cocoa liquor from D_50°C = 999 min to D_90°C = 26 min and for dark chocolate of D_50°C = 1574 min. z-values were found to be z = 20 °C in cocoa liquor and z = 14 °C in dark chocolate. This study demonstrates that the conching process alone does not ensure the inactivation of Salmonella spp. in different chocolate masses and that an additional decontamination step at the beginning of the process as well as an HACCP concept is necessary during chocolate production to guarantee the absence of Salmonella spp. in chocolates and related products.     

Application of alpha-tocotrienol for detection of palm mid-fraction in dark chocolate formulation

Following model studies, the detection of palm mid-fraction (PMF) added to cocoa butter (CB) in chocolate formulations was investigated. Different levels of PMF (0–25%, CB basis) were added to CB in chocolate. High performance liquid chromatography was then used to detect the presence of PMF in chocolate using α-tocotrienol as an indicator. The results, in line with the model studying indicated that increasing the amount of PMF added to CB resulted in a significant (P < 0.05) increase in the concentration of α-tocotrienol in chocolate; a linear plot (R ² = 0.9837) was obtained with standard error of 1.986. A validation test was conducted to verify the equation obtained from the regression analysis. The high R ²-value obtained indicated a good accuracy, reflecting a close relationship between experimental and theoretically predicted values. The applied indicator performed well beyond the level of the statutory limit of 5% PMF addition on a chocolate basis that verified the previously studied model.     

ELECTRIC FIELD EFFECTS ON THE THERMAL CONDUCTIVITY OF MILK CHOCOLATE DETERMINED USING THE "MIRROR IMAGE METHOD"

Electrorheological fluids exhibit changes in flow properties when exposed to an electric field. Generally, these fluids display an increase in apparent viscosity and a greater yield stress in the presence of a voltage. Another attribute of some electrorheological fluids is the ability to enhance heat transfer, allowing for greater control over heating and cooling unit operations. This paper examined the effects of an applied voltage on the thermal conductivity of molten milk chocolate, a material known to be an electrorheological fluid. The method used to measure the thermal property was based on the “mirror image’ concept. In this technique, identical disks sandwich a heat source providing a constant heat flux directed evenly between the two sides. Knowing the heat flux and the boundary temperatures of the sample gap, an analytical solution was used to calculate the thermal conductivity and specific heat. An applied electric field of up to 450 V mm^?1 at 60 Hz was found to have no significant effect on the heat transfer properties of milk chocolate. The thermal conductivity was found to have an average value of 0.163 W m^?1 K^?1 over a temperature range varying from 25 to 60C. The measurement technique, however, proved to be a rapid method for determining thermal properties that may be useful in investigating other liquid foods.     

Modeling oil migration in two-layer chocolate–almond confectionery products

Migration of oil from high oil content fillings into the surrounding chocolate coatings results in product quality changes of filled confections. The objective of this study was to evaluate the mass transfer of liquid oil in two-layer model confectionery samples prepared from four almond products and dark chocolate. Experimental data were acquired using magnetic resonance imaging (MRI). The spatial and temporal experimental data of the liquid oil signal of the almond product and chocolate were modeled using a Fickian diffusion model. Solutions to the diffusion model were derived using both Laplace transform analytical solution and a finite difference numerical solution. For both methods, the boundary condition between the two layers incorporated a partition coefficient. MatLab’s nlinfit routine coupled with the diffusion equation solution provided estimates of the diffusion coefficients, D_a (almond products) and D_c (chocolate), and the partition coefficient. The diffusion coefficient values for the chocolate region ranged between 3 × 10⁻¹¹ m²/s and 6 × 10⁻¹¹ m²/s; the diffusion coefficient values for the almond products were an order of magnitude greater than that of chocolate.     

Effect of heat and thermosonication treatments on watercress (Nasturtium officinale) vitamin C degradation kinetics

The use of ultrasound in food processing creates novel and interesting methodologies, which are often complementary to classical techniques. In this work, the effect of heat and the combined treatment heat/ultrasound (thermosonication) on the thermal degradation kinetics of vitamin C in watercress (Nasturtium officinale) was studied in the temperature range of 82.5 to 92.5 °C. First order reaction kinetics adequately described the vitamin C losses during both blanching processes.The activation energies and the reaction rates at 87.5 °C for heat (H) and thermosonication (Ts) treatments were, respectively, E_avitCH = 150.47 ± 42.81 kJ mol^− 1 and E_avitCTs = 136.20 ± 60.97 kJ mol^− 1, and k_{87.5 °CvitCH} = 0.75 ± 0.10 min^− 1 and k_{87.5 °CvitCTs} = 0.58 ± 0.11 min^− 1. No significant differences (P > 0.05) were detected between both treatments. The thermosonication treatment was found to be a better blanching process, since it inactivates watercress peroxidase at less severe blanching conditions and consequently retains vitamin C content at higher levels. The present findings will help to optimise the blanching conditions for the production of a new and healthy frozen product, watercress, with heat and a new blanching process methodology.

Industrial relevance

Thermosonication blanching can be useful since it reduces processing times, and consequently minimizes the adverse effects of heating on watercress quality. This new application will provide good material, in terms of vitamin C, for further processes, and can be an excellent alternative to the traditional heat treatment.     

Garlic dehydration inside heat exchanger-evacuated tube assisted drying system: Thermal performance,drying kinetic and color index

An experimental investigation was done on an advanced evacuated tube-assisted solar drying system without and with load conditions at various water flow rates (10 L/h, 20 L/h, and 30 L/h) to evaluate its performance analysis. 79.56 °C maximum greenhouse air temperature was recorded without load at 30 L/h water flow rate with an average solar intensity of 850 W/m². Highest value of drying rate (DR) is 1.48 kgH₂O/kg dry solid/h and the maximum efficiency of solar collector (SC) and solar dryer (SD) is 43.62% and 55.28%, respectively, at 30 L/h water flow rate. Garlic was dehydrating from 70% to 8% (wb) moisture content (MC). The maximum exergy efficiency (EE) and minimum exergy loss were 57.64% at 30 L/h water flow rate and 4.58 W at 10 L/h water flow rate. Quality assessment is also carried out for dried garlic samples in the heat exchanger –evacuated tube assisted drying system (HE-ETADS). Color conservation (indices) of dehydrated garlic sample is best in HE-ETADS (L_o = 60.42, a_o = −0.92, and b_o = 11.54) in comparison to old-style (traditional) drying process (L_o = 58.89, a_o = - 0.67, and b_o = 5.99). Therefore, the developed drying system represented not only good financial returns but also better product quality. The present system provides interesting options for the entry of this type of collectors in medium-scale applications in the agricultural and industrial sectors.     

Modelling sorption kinetic of sponge cake crumb added with milk syrup

Sponge cake is an ideal product to be soaked with liquids, due to its porous structure; baking process causes differences in crumb features through the cake; therefore, it is important to know how these variations can affect its sorption capacity. The aim of this work was to study the relation between crumb cake structure at different levels (bottom, centre and top) and sorption characteristics when adding milk syrup. The Peleg model was the best to fit sorption data (R² > 0.9), showing that the rate constant (k₁) diminished as the cell density (r = 0.920) and gelatinisation percentage (r = 0.890) decreased, while moisture (r = ?0.999) and a_w (r = ?0.994) increased; cell density only correlated with gelatinisation percentage (r = 0.997); micrographs showed that the sorption rate increased as more gelatinised starch and coagulated protein were found. To optimise the sorption process, the gelatinisation degree and crumb structure (cell density and types of pores) should be considered.     

Modelling kinetics of watercress (Nasturtium officinale) colour changes due to heat and thermosonication treatments

Watercress (Nasturtium officinale) colour changes due to blanching by heat and a combined treatment of heat/ultrasound (thermosonication) were studied in the temperature range of 82.5 to 92.5 °C. The application of thermosonication was intended to enable less severe blanching treatments and, therefore, improve the quality of the blanched product. The thermosonication blanching processes promoted changes of the green colour (aⁿ parameter) at a higher rate (P < 0.05), when compared with the heat blanching processes. No significant differences (P > 0.05) were detected between heat and thermosonication blanching processes in terms of the colour parameters Lⁿ, bⁿ and TCD changes. In both treatments, a fractional first order model fitted well the experimental data for Lⁿ, aⁿ and bⁿ (R_H² = 0.99; R_Ts² = 0.99) and TCD (R_H² = 0.92; R_Ts² = 0.96) colour parameters.The chlorophylls content showed no significant differences (P > 0.05) between thermally treated and thermosonicated watercress samples.The present findings will help to evaluate the effectiveness of thermosonication as a novel process to replace the classical heat treatment.Industrial relevanceConventional blanching commonly results in severe losses or destruction of nutrients due to process intensity and extended process times. Consequently, the attempts to use the synergistic effects of heat and ultrasound (at least) for enzyme inactivation are of high relevance. The results, although not conclusive, indicate, that they may aid optimization of blanching processes.     

Survival kinetics of Ephestia kuehniella eggs during 46–75 °C heat treatment

The effect of heat treatment on the survival of Ephestia kuehniella eggs was examined. Samples of 60 eggs were immersed in hot water at constant temperature in the 46–75 °C range for 5–1200 s. Following heat treatment and cooling, the eggs were stored at 24 ± 1 °C in a growth chamber for 7 days before survival evaluation. Statistical analysis of the data demonstrated that the thermal survival kinetics were best represented by a first-order reaction. The rate constant had an Arrhenius-type dependence over the 54–75 °C temperature range. Kinetic parameters were estimated by non-linear regression. The activation energy (E_a) and rate constant (k_ref) at the reference temperature (T_ref = 64.8 °C), were determined as 102.2 ± 6.2 kJ mol⁻¹ and 0.061 ± 0.003 s⁻¹, respectively, over the 54–75 °C temperature range. A 0.01% survival rate was obtained after 50 s at 75 °C. The data at temperatures below 50 °C were not in accordance with those at higher temperatures. Above this temperature, mortality was likely due to physiological disorders, as noted on a DSC thermogram.     

Modelling tempering behaviour of dark chocolates from varying particle size distribution and fat content using response surface methodology

Central Composite Rotatable Design (CCRD) for K = 2 was used to study the combined effects of multi-stage heat exchangers for Stages 1 (14–30 °C) and 2 (12–28 °C) coolant temperatures at constant Stage 3 coolant and holding temperatures during tempering of dark chocolates using laboratory-scale mini-temperer. Quantitative data on chocolate temper index (slope) were obtained for products with varying particle size distribution (PSD) (D₉₀ of 18, 25, 35 and 50 μm) and fat (30% and 35%) content. Regression models generated using stepwise regression analyses were used to plot response surface curves, to study the tempering behaviour of products. The results showed that both Stage 1 and Stage 2 coolant temperatures had significant linear and quadratic effects on the crystallization behaviour causing wide variations in chocolate temper index during tempering of products with variable PSD and fat content. Differences in fat content exerted the greatest variability in temperature settings of the different zones for attaining well-tempered products. At 35% fat content, changes in PSD caused only slight and insignificant effect on tempering behaviour. No unique set of conditions was found to achieve good temper in dark chocolate with a specified tempering unit. Thus, different combinations of temperatures could be employed between the multi-stage heat exchangers to induce nucleation and growth of stable fat crystal polymorphs during tempering. Variations in tempering outcomes of the dark chocolates were dependent more on the fat content than PSD.

Industrial relevance

Tempering consists of shearing chocolate mass at controlled temperatures to promote cocoa butter crystallization in a stable polymorphic form. During industrial processing, multi-stage heat exchangers are used to control temperature adjustments to promote formation of appropriate stable polymorphic crystals to obtain products with good snap, colour, contraction, gloss and shelf life characteristics. The process employs varying time–temperature throughputs of the multi-stage units making it difficult to obtain standard tempering conditions for products with variable particle sizes and fat content, thus prolonging equipment standardization periods with consequential effects on processing times and product quality characteristics. Modelling the tempering behaviour of dark chocolates from varying PSD and fat content would enhance our knowledge and understanding on the optimal temperature conditions for obtaining good tempered products during industrial manufacture, with significance for reducing processing (tempering) times and assurances in quality and shelf characteristics.     

Purification and properties of a heat-stable enzyme of <Emphasis Type="Italic">Pseudomonas fluorescens</Emphasis> Rm12 from raw milk

Pseudomonas fluorescens Rm12 is a kind of Psychrotrophic bacteria growing in cold raw milk. It produced an extracellular heat resistant protease with an estimated molecular weight of 45 kDa by size exclusion chromatography and SDS-PAGE under both reducing and non-reducing conditions. The enzyme, designated Ht13, was purified to electrophoretic homogeneity from the culture supernatant by sequentially using ammonium sulfate precipitation, ion-exchange chromatography, hydrophobic chromatography and size exclusion chromatography. The specific activity of the enzyme increased 115.5-folds. The optimum pH value and temperature of Ht13 were 7.5 and 40 °C, respectively. Based on its biochemical characteristics, Ht13 can be included in the group of metalloproteases, which was inhibited by 1, 10-phenanthroline and EDTA but not by pepstatin A, chymostatin, STI, E-64, BBI, PMSF and pAPMSF. Mn²⁺ has positive effect on activity and can increased the heat resistance capability, while Ca²⁺ had a negligible effect. For the hydrolysis of azocasein, the Km was 0.012 mg mL⁻¹. The enzyme showed typical heat-stable behavior. After treatment of 160 °C 20 s, the residual activity was 9%. The half-life of the enzyme at 160 °C in buffer with Mn²⁺ was approximately 12 s. Among several main milk proteins, Ht13 can cleave α_s-casein, β-casein and κ-casein. The sequence of 1st–16th amino acids of N-terminal was MSKVKDKAIVSAAQAS, which was same as those proteases excreted from some other P. fluorescens. However, their molecular weights, the activation ion and amino acid composition were different, suggesting Ht13 from P. fluorescens Rm12 is a novel protease.     

Relationship between rheological,textural and melting properties of dark chocolate as influenced by particle size distribution and composition

In dark chocolate, rheological properties during processing are influenced by particle size distribution (PSD), fat and lecithin contents with consequential effects on finished texture and melting characteristics. Multivariate regression, correlation and principal component analyses (PCA) were used to explore their interrelationships. A 4 × 3 × 2 factorial experiment was conducted with varying PSD [D ₉₀ (90% finer than this size) of 18, 25, 35 and 50 μm], fat (25, 30 and 35%) and lecithin (0.3 and 0.5%). Rheological properties (yield stress and apparent viscosity), textural properties (firmness, index of viscosity and hardness) and melting index (duration) were respectively measured using shear rate-controlled rheometer, TA.HD Plus texture analyzer and differential scanning calorimetry. The PSD, fat and lecithin contents significantly influenced all rheological, textural properties and some melting characteristics. Increasing particles sizes reduced yield stress, apparent viscosity, firmness, index of viscosity, hardness and melting index of products with greatest influence with 25% fat and 0.3% lecithin, reduced with increasing fat and lecithin contents. There were high correlation (r = 0.78–0.99) and regression coefficients (R ² = 0.59–0.99) among the rheological, textural and melting index indicating their high inter-relationships. In PCA, the rheological, textural and melting index accounted for >95% variance in the data.     

Influence of fermentation parameters on phytochemical profile and volatile properties of mulberry (Morus nigra) wine

In the present study Box–Behnken Design was employed to analyse the effects of fermentation parameters such as temperature (T _F), pH, inoculum size (I _S) and °Brix (B_X) on total phenolic concentration (TPC), total flavonoid concentration (TFC), total anthocyanin concentration (TAC), ethanol concentration (ETHC), total higher alcohol concentration (THAC) and total ester concentration (TESC) for the development of a phytochemical‐rich wine using mulberry as a substrate. The results demonstrated that fermentation parameters significantly alter the wine characteristics. Hence, a wine with excellent consumer preference (overall acceptability of 8.51) and high concentration of phytochemicals (TPC = 6014.03 ± 27.80 mg L⁻¹, TFC = 4791.35 ± 21.22 mg L⁻¹, TAC = 1480.72 ± 5.33 mg L⁻¹) as well as good aromatic properties (ETCH =82.85 ± 0.87 g L⁻¹, THAC =249.91 ± 0.31 mg L⁻¹ and TESC =52.55 ± 0.17 mg L⁻¹) with high antioxidant activity (DPPH =220.18 mmol·l⁻¹) was obtained at optimized fermentation conditions of T _F = 25°C, pH = 4.00, I _S = 10% (v /v) and B_X = 26. The results from the present study might contribute to strengthening the development of wine containing high concentrations of phytochemical compounds with attractive olfactory attributes. Copyright © 2017 The Institute of Brewing & Distilling     

Effect of active and modified atmosphere packaging on quality retention of dark chocolate with hazelnuts

The present study investigated the effect of active and modified packaging as well as packaging material oxygen permeability on quality retention of dark chocolate with hazelnuts. Dark chocolate was packaged in: a) polyethylene terephthalate//low density polyethylene (PET//LDPE), and b) polyethylene terephthalate coated with SiOx//low density polyethylene (PET-SiOx//LDPE). Samples were packaged either under, vacuum or N₂ or with an oxygen absorber and stored in the dark at 20 °C for a period of 12 months. “Commercial” control samples for comparison purposes consisted of chocolate packaged in aluminum foil in air while “model” control samples used for sensory evaluation consisted of chocolate packaged in glass jars and stored at ? 18 °C. Quality parameters monitored were: peroxide value, hexanal content, color, fatty acid composition and volatile compounds. Of the sensory attributes color, texture, odor and taste were evaluated. PV ranged between 0.80 for fresh dark chocolate with hazelnuts and 6.51 meq O₂/kg chocolate fat for commercially packaged samples after 12 months of storage. Respective values for hexanal were 0.53 and 7.56 mg/kg. % Saturated fatty acids (SFA) increased with a parallel decrease in monounsaturated fatty acids (MFA) and polyunsaturated fatty acids (PUFA) after 12 months of storage mainly in least protected samples (commercial package). Likewise, after 12 months of storage an increase in concentration of aldehydes, ketones, alcohols and alkanes (p < 0.05) with a parallel decrease in pyrazines where observed especially in case of least protected products after 6 and 12 months of storage. In general after 12 months of storage chocolate showed whitening of the surface resulting to an increase in L* and a* values (p < 0.05) and a decrease in b* value. Dark chocolate with hazelnuts retained acceptable quality for ca. 8 months in commercial packages. For samples packaged in PET//LDPE irrespective of storage atmosphere the shelf life was 8 to 9 months and for samples packaged in PET-SiOx//LDPE irrespective of storage atmosphere the shelf life was 11 months. Finally for samples packaged with an oxygen absorber irrespective of packaging material the shelf life was at least 12 months.Industrial relevanceChocolate packaged with an oxygen absorber in a barrier packaging material will maintain its aroma, taste and nutritional quality substantially longer than other packaging methods.     

Investigation and modelling of natural convection and conduction heat exchange: study on food systems with modified starch by means of computational fluid dynamics

This study is focused on the effects of starch gelatinisation on heat exchange in food systems containing four modified starch concentrations (0, 2, 6 and 10%). Viscosity profiles of samples were experimentally measured: the effect of gelatinisation was evident, particularly at 6% and 10%, where the viscosity increased from 0.010 to 70 Pa s and to 1507 Pa s, respectively. The heat exchange rate showed a decrease with the increasing of starch concentration, and the effects were observed until 6%. Four Computational Fluid Dynamics (CFD) models were also developed, experimentally validated (RMSE < 1.5 °C) and used to study the heat exchange. Velocity profiles showed that the convective flows slowed down from 2.5 to 0 mms^?1 after the gelatinisation. Finally, the effects on the slowest heating/cooling zone (SHZ/SCZ) location in the CFD models were studied: at 0% and 2%, the SHZ settled 15 and 80 mm from the bottom of jars in heating and cooling phase, respectively. At 6% and 10%, before the starch gelatinisation phase, the SHZ was located in a similar position of the 0% and 2% while when the gelatinisation occurred the SHZ slightly moved towards the geometric centre (50 mm) as for an only‐conductive product.     

Prediction of convective heat transfer coefficient during deep-fat frying of pantoa using neurocomputing approaches

Deep-fat frying (DFF) is the major processing step in preparation of pantoa, a popular Indian dairy sweetmeat. In this study, the dough for pantoa was rolled into balls of 15 g, and fried in sunflower oil at 125, 135 and 145 °C for 8 min. Convective heat transfer coefficient, which defines the heat transfer characteristics of the product during DFF, was determined using one-dimensional transient heat conduction equation as 92.71–332.92 W·m^− 2·K^− 1. Neurocomputing techniques such as connectionist models and adaptive neurofuzzy inference system (ANFIS) were compared vis-à-vis multiple linear regression (MLR) models for prediction of heat transfer coefficient. A back-propagation algorithm with Bayesian regularization optimization technique was employed to develop connectionist models while the ANFIS model was based on Sugeno-type fuzzy inference system. Both connectionist and ANFIS models exhibited superior prediction abilities than the classical MLR model. Amongst the three approaches, the hybrid ANFIS model with triangular membership function and frying time and temperature as input factors gave the best fit of convective heat transfer coefficient with R² as high as 0.9984 (99.84% accuracy) and %RMS value of 0.1649.Industrial relevanceConvective heat transfer coefficient defines the heat transfer characteristics of a product during frying. Accurate prediction of heat transfer coefficient is important for design of process equipment and saving energy during commercial production. Developing models to predict heat transfer and the coefficients have been a challenge. Neurocomputing is one of the emerging intelligent technologies with analogies to biological neural systems. Therefore, it has the capability to predict complex relationships in food systems. Neurocomputing approaches such as connectionist and ANFIS models are now widely used in the food industry to predict various engineering properties of food, optimization of various transport processes, unit operations and formulating new products and product characteristics. No attempt has been made to predict the heat transfer coefficient during frying of pantoa. In this study, the convective heat transfer coefficient of pantoa was predicted using connectionist models and ANFIS techniques. These neurocomputing techniques are expected to alleviate the difficulties in conventional heat transfer modeling.     

Vacuum impregnation on apples with grape juice concentrate: Effects of pressure,processing time,and juice concentration

Apple cubes were subjected to vacuum impregnation using grape juice concentrate. The effect of pressure reduction (VP = 100–500 mmHg), immersion time (t = 10–30 min), and concentration of grape juice (C = 40–60°Brix) on impregnation parameters were evaluated using response surface methodology. Second-order polynomial equations were developed (R² > 0.895) to describe the behavior of water loss, total soluble solids, L*, a*, Hue, total color difference, the color of impregnated/treated areas (A_U/A_OP), antioxidant activity, total monomeric anthocyanin, and dimensionless volume (V/Vo) in the impregnated product. VP had a significant (p ≤ 0.05) effect on mass transfer parameters, color parameters, A_U/A_OP, and bioactive compounds. However, at 60°Brix and 500 mmHg, the lower V/Vo values were reached due to cell disruption. Therefore, it is recommended to use a VP = 500 mmHg and t less than 20 min to significantly impregnate compounds and obtain a product without considerable morphometric modification.