Most of the food processing operations involve the use of heat which generally causes alteration, and degradation of natural pigments, resulting in lower stability. One of the stability enhancement methods is co-pigmentation. This study aimed to determine effect of catechin co-pigment on stability of anthocyanins in Clitoria ternatea (or butterfly pea flower) extract. Degradation kinetics of anthocyanins in the extract were evaluated at three temperatures (28, 60, and 90℃). The effect of co-pigment ratio (catechin: anthocyanins at 1:1, 50:1 and 100:1 by weight) on the stability of anthocyanin extract at 90℃ was determined by the pH differential method. It was found that anthocyanin degradation followed the zero- order kinetics at all temperatures; the degradation rate increased as the temperature increased. At a lower pH, anthocyanins became more stable. An increase in the co-pigment ratio significantly retarded the degradation anthocyanins at 90℃. In addition, co-pigmentation also intensified the color of butterfly pea extract. The highest anthocyanin stability was obtained at co-pigment ratio of 100:1.

Charcoal-grilling may lead to contamination of food with carcinogenic polycyclic aromatic hydrocarbons (PAHs) during the grilling process. The objective of this work was to determine the effect of charcoal preparation on 16 USEPA priority PAHs in the smoke produced during the grilling process. Firstly, mangrove charcoal was prepared at carbonisation temperatures of 500, 750 and 1000 °C. The charcoal were then preheated by burning at 650 °C. This preheating step is usually used to prepare hot charcoal for the grilling process in the food industry. In this study, charcoal was preheated at different burning times at 5, 20 min and 5 h, at which time partial and whole charcoal glowed, and charcoal was completely burnt, respectively. Finally, PAHs in the smoke were collected and determined by GC/MS. The result showed that charcoal prepared at a carbonisation temperature of 500 °C had higher levels of PAHs released into the smoke. In contrast, charcoal produced at 750 and 1000 °C had lower PAHs released for all burning times. In addition, PAHs released for 5, 20 min and 5 h of burning time were about 19.9, 1.2 and 0.7 µg g(-1) dry charcoal for charcoal produced at 500 °C, and about 0.9-1.4, 0.8-1.2 and 0.15-0.3 µg g(-1) dry charcoal for charcoal produced at 750 and 1000 °C, respectively. Therefore, this research suggests that food grilled using charcoal carbonised at a high temperature of about 750 °C presents a lower risk of PAH contamination. In addition, in the preheating step, whole charcoal should fully glow in order to reduce the PAH content in charcoal before grilling.

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This research aimed to study the Maillard reaction pathway in chicken meat. Owing to the complexity of real chicken meat, which is composed of many different types of amino acids and reducing sugars, the experiment was initiated with a glucose/lysine model system with the same concentration ratio of reactants as found in chicken meat. By considering glucose as the rate‐limiting substrate, a kinetic model of the glucose/lysine model system was developed. Methylglyoxal (MG) was found to be the principal important α‐dicarbonyl compound intermediates that further reacted to form melanoidins. Pyridine was a major volatile compound in this model system. The optimized kinetic model was then further validated in a chicken extract, for which the Maillard reaction mechanism has not been elucidated. However, the kinetic model of the glucose/lysine system could not explain the Maillard reaction in the chicken extract, presumably because both types of intermediates and reaction pathway depend on the reactants. Thus, a kinetic model of the Maillard reaction in the chicken extract was developed based on the main types of detected intermediates. Overall, MG was the central intermediate and acted as a substrate for the formation of furfural, volatile compounds, melanoidins, and unknown carbonyl compound(s) (Cn). Pyrazines and aldehydes were the major volatile compounds in the chicken extract.

Heat and mass (moisture) transfer during deep-frying of frozen composite food was simultaneously modeled using the moving boundary concept. An explicit finite difference method was used to solve the proposed model. A model food composed of a chicken breast coated with batter at both ends was used to validate the predicted center temperature during frying at the specified oil temperatures. Thermal denaturation of actin was, in this study, chosen as the quality index of the meat-based product being fried, and its corresponding kinetic parameters were experimentally determined from the DSC data with the assumption of a single-step irreversible reaction. Good agreement between the predicted and observed results could be obtained when a 0.3 mm vapor gap between material layers was added to the proposed mathematical model. Sensitivity studies showed that the varying oil temperature of +10 O C did not dramatically affect the center temperature profile of the product. Oppositely, the center temperature of the product was notably affected by the gap width in the order of 0.1 mm and the batter thickness in the order of 1 mm.

Since determination of the slowest heating zone (SHZ) is a tedious task in thermal process establishment, mathematical simulation has been introduced. In this research, a numerical study on 2-dimensional natural convection in a cylindrical can during sterilization of liquid food (1% Carboxy-methyl cellulose, CMC) was performed to simulate the flow pattern and temperature distribution. SHZ and sterilizing value (F 0) were also determined. Temperature dependent viscosity and density were assumed, while heat capacity and thermal conductivity were kept constant. To represent the actual mechanisms of heating in an overpressure retort, nonisothermal boundary condition (B.C.) was applied; the results were compared with isothermal B.C. The non-isothermal B.C. resulted in a slower heating rate and the simulated temperature profiles that agreed well with the experimental data (2.6% RMSE). Simulated SHZ was forced to move downwards from the geometric centre to the bottom of the can and stayed at about 10% of the can height from the bottom. SHZ moved closer to the wall (at r = R/2) as a result of the secondary flow due to natural convection. An increase in viscosity and thermal conductivity and a decrease in specific heat and density of higher than 5% resulted in a significantly lower F 0-value.

The aim of shrimp soaking is to improve functional properties and yield of a shrimp product. The weight variation in the soaking step in actual production is larger than that in the laboratory due to many uncontrollable factors that have not been identified. The objective of this work, therefore, was to investigate the causes that provoke the difference in yield calculation between the laboratory and the real production conditions to improve the soaking process of shrimp within the regulated time. First, the effect of storage time in ice (0 and 24 h) on soaking yield variation was studied. Then, the effect of soaking equipment, i.e. flat bottom tank with rod impeller and cone bottom tank with paddle blade impeller, on weight variation was determined. The result revealed that the iced storage time and the design of soaking equipment had no significant effect on the variations of yield and weight (p ≥ 0.05). Nevertheless, water holding capacities after soaking and cooking were significantly influenced by the iced storage period (p < 0.05). The result revealed that the 24-h iced storage significantly reduced the yields of soaking, cooking, and freezing.