Prediction of thiamine content in convective heated meat products

It is reported that thiamine is one of the most heat labile water soluble vitamins. It is therefore important to control the destruction of this vitamin during heating, reheating and keeping warm of different food items.
In this study the kinetics of thiamine degradation in ground meat were determined. The losses during roasting of a minced meat loaf under different air conditions in a forced convection oven were calculated by computer simulations. The actual losses were analysed by a chemical method. The kinetics were found to be approximately of first order. The time-temperature curves and the thiamine degradation in the loaves roasted under fairly mild conditions were easier to predict than the ones roasted at higher air temperature. This is partly due to the formation of the crust which has different thermal properties and gives different chemical changes from the inner parts of the loaf. The humidity and the velocity of the air does not effect the crust formation as much as the air temperature. This fact limits the prediction of thiamine degradation to lower air temperatures.     

NONLINEAR CONSTRAINED OPTIMIZATION of THERMAL PROCESSING II. VARIABLE PROCESS TEMPERATURE PROFILES to REDUCE PROCESS TIME and to IMPROVE NUTRIENT RETENTION IN SPHERICAL and FINITE CYLINDRICAL GEOMETRIES

Conventional methods for thermal processing of foods use constant processing temperature profiles (CPTPs) for a prescribed processing time, which is based on achieving a required microbial lethality to comply with public health standards. This also results in degradation of nutrients and quality factors. the variable process temperature profiles (VPTPs) obtained by using optimization methods can reduce quality losses and/or processing time compared to CPTPs. the objective of this research was to evaluate VPTPs using the Complex Method to reduce the processing time and/or improve quality retention for a specified level of lethality in thermal processing of conduction heated foods. the VPTPs were obtained for volume average retention of thiamine considering different sizes of spheres (small and large) and finite cylinders (small and large), and the thiamine retention and processing time results were compared with a conventional method (processing at 121.1C) for a specified lethality level. the use of VPTPs resulted in a 37 and 10% decrease in processing times in spherical and 40 % and 6 % for finite cylindrical shapes, for the same objective function value and specified lethality compared to the CPTP process. For the same processing time, the improvements in thiamine destruction were 3.7 and 2 % for spheres, and 3.9 and 2.2% for finite cylinders.     

EFFECT OF GAMMA RAY IRRADIATION AND FRYING ON THE THIAMINE CONTENT OF BACON

The effects of ionizing irradiation and frying on the thiamine and riboflavin content of bacon were determined. Significant destruction of thiamine but not riboflavin occurred during both the irradiation and frying. The destruction of thiamine was found to be directly related to the dose of ionizing radiation or the degree of cooking. Frying before irradiation, reduction of water content by lyophilization, and irradiation at - 40°C rather than 2°C produced significantly greater retention of thiamine. Frying the bacon following irradiation produced radiation dose-related, nonadditive, increased destruction of thiamine. The protective effect of frying before irradiation was not directly linked with the reduction of moisture by frying.     

Thiamine destruction during extrusion cooking as an indicator of the intensity of thermal processing

Assessment of the intensity of high temperature-short time (HTST) extrusion cooking was studied by measuring the extent X_A of thiamine destruction. Small quantities of thiamine hydrochloride (0.1–0.7 g per 100 g) were mixed with wheat flour (containing ∼ 14% water) prior to extrusion experiments. Results indicate that thiamine destruction follows an apparent first-order reaction and that the rate constant K of destruction, calculated from near isothermal extrusion experiments at 133, 142 or 152°C (product temperature), follows an Arrhenius relationship with an activation energy of 49.9 kJ/mol.
K values were calculated from experimental determination of X_A and of the residence time distribution (RTD) in the effective heating zone of the extruder.
The influence of product temperature (just before the die), water content during extrusion and speed of screw rotation on the overall K (for non-isothermal extrusion experiments) was determined and analysed by multiple regression. Results show that thiamine destruction X_A can be predicted by means of a linear mathematical model.
Each experimental X_A value can be used, in combination with Arrhenius equation constants and RTD, to express a given extrusion process in terms of equivalent isothermal temperature and equivalent plug flow residence time.     

Optimisation of thermal processing — A review

The mathematical methods for optimising the effects of heat processing food products are reviewed in relation to microbial destruction, nutrient destruction, cooking value and loss of quality. Some data are presented for the kinetics of the various thermal effects. The results obtained by various workers are presented with particular reference to nutrient retention.     

Effect of several heat treatments and frozen storage on thiamine, riboflavin, and ascorbic acid content of milk

This research was designed to test the reliability of modified Association of Official Analytical Chemists methods for quantitation of thiamine, riboflavin, and ascorbic acid in milk; to ascertain the extent of destruction of those vitamins by modern heat processing; and to determine if it is truthful to report that heat processing does not reduce milk's nutritional properties insofar as those vitamins are concerned. Milk was processed continuously at four time-temperature treatments, including that used for modern commercial sterilization. Both raw and heated milks were analyzed immediately for content of heat labile vitamins; subsamples were packaged in amber plastic bottles, frozen, and subsequently analyzed for vitamin content after 14 days storage. Analyses were by modified Association of Official Analytical Chemists fluorometric techniques.     

Interaction of thiamine with reducing sugars

The influence of reducing sugars (xylose, glucose and maltose) on the rate of thiamine destruction was studied at 95°C in aqueous solutions buffered to pH 6·75. The rate of thiamine loss was found to be dependent on both the nature of the reducing sugar and on the concentration of the reducing sugar. Thiamine destruction rates, in the presence of a reducing sugar, decreased in the order: xylose > glucose > maltose. In addition, for the three reducing sugars studied, thiamine loss was enhanced as reducing sugar concentration increased. It was found that, when a reducing sugar was present, the rate of thiamine loss increased by as much as 37%.     

CENTERPOINT NUTRIENT DEGRADATION IN HEAT PROCESSED CONDUCTION HEATING FOOD MODEL

A methodology was developed for the evaluation of centerpoint nutrient degradation in conduction heating canned food subjected to thermal processing. the methodology involved sealing of 75μL aliquote of test solution in a leakproof pressure-stable stainless steel capsule, placing the capsule at the geometric center of a can filled with a conduction heating simulated food prior to the closure, and recovering the capsule and analyzing the contents following a given thermal treatment. Experiments carried out using aqueous solutions of ascorbic acid and thiamine indicated good reproducibility of the results. Employing kinetic data for thermal destruction of the nutrients and center temperature-time history of the food simulant obtained from several simultaneously processed cans, the centerpoint nutrient retention predicted by several models agreed favorably with the experimental results.     

Calculating the degradation kinetic parameters of thiamine by the isothermal version of the endpoints method

Thiamine (vitamin B₁)'s degradation during thermal processing and storage of foods is known to follow first-order kinetics, where the rate constant's temperature-dependence can be described by the two-parameter Arrhenius equation. In agreement with previous reports, a simpler two-parameter exponential model could replace the Arrhenius equation in thiamine degradation without sacrificing the fit. Theoretically, the exponential model's two parameters can be estimated from the concentration ratios after two isothermal exposures by solving a pair of simultaneous nonlinear algebraic equations of which they are the two unknowns. Once calculated, these two parameters can be used to reconstruct the entire degradation curves to which the two endpoints belonged, and to predict those at any other exposure in a pertinent temperature range. The concept and mathematical calculation procedure were implemented in a freely downloadable interactive Wolfram Demonstration, with which the user solves the equations by moving sliders on the screen to match the reconstructed degradation curves with the experimental endpoints. The method was tested with computer simulations and with published experimental data on thiamine's degradation in a model solution, beef, pasta and salmon, over large temperature ranges and exposure times, and validated by comparing thiamine's predicted final concentration ratios with those reported at temperatures not used in the kinetic parameters calculation. The described method and interactive calculation program can facilitate and economize the study of thiamine degradation in stored foods by eliminating the need to record entire sets of isothermal degradation curves.     

Compression Heating and Temperature Control for High-Pressure Destruction of Bacterial Spores: An Experimental Method for Kinetics Evaluation

High-pressure (HP) processing is considered as an alternative technique for thermal sterilization of high quality foods. Adiabatic compression during pressurization allows for quick increase in temperature of food products, which is reversed when the pressure is released, thereby providing rapid heating and cooling conditions and hence short process times. However, during the pressure holding time, the product experiences a temperature drop as a result of heat loss to the vessel. The temperature variation during the process and the synergistic effect of temperature and pressure make it difficult to get the required accurate data on microbial spore destruction kinetics. In this study, a polyoxymethylene (POM)-insulated chamber was evaluated for temperature control in the test sample during pressure treatment. Temperature variations in the HP system were measured in milk test samples inside the POM insulator and pressure medium in the HP vessel under various conditions of pressures (500–900 MPa) and initial temperatures (20–80 °C). Results demonstrated that the POM chamber had good thermal-insulation characteristics under pressure and was able to maintain stable operating conditions for microbial spore destruction kinetics. Based on the measured adiabatic temperature change, the required initial temperatures for the test sample and pressure medium were generated as a quadratic function of pressure and temperature. The setup was then verified for pressure inactivation of Clostridium sporogenes (PA 3679) spores in ultra-heat-treated milk. The better temperature stability of test samples during treatment provided a means to gather accurate data on HP destruction kinetics of the microbial spores.     

RELATION of BACTERIAL DESTRUCTION to CHEMICAL MARKER FORMATION DURING PROCESSING BY THERMAL PULSES1

This paper presents a formulation in dimensionless terms of the equations pertaining to first-order processes that follow Arrhenius kinetics, and applies them to problems in food thermoprocessing. the need for it arose from attempts to understand the relation between destruction of pathogenic microorganisms and formation of chemical markers in the food. During processing food is subjected to a thermal pulse that affects the markers and microorganisms. the dimensionless formulation makes it convenient to obtain equations expressing the relation between the decadic reduction in microbial population and the rise in marker concentration for temperature-time profiles of forms hitherto not conveniently calculable. Measurements of chemical markers can be used with these formulas to predict destruction of microorganisms. Examples are given of calculations demonstrating the feasibility of this approach when a single marker is monitored.     

Studies on some water-soluble vitamins retention in potatoes and cow peas as affected by thermal processing and storage

The effects of the commercial thermal processing and storage on the retention of ascorbic acid, thiamine and riboflavin in potatoes and cow peas have been studied. Samples have been collected after washing, blanching and thermal processing operations. Washing had no significant effect on the levels of these vitamins in both potatoes and cow peas. Either blanching (at 100 degrees C for 2 min) or thermal processing (at 121 degrees C for 20 min) had a great effect on the retention of ascorbic acid, thiamine and riboflavin. While the retention of ascorbic acid and thiamine had been affected by the storage conditions (at 25 degrees C for 6 month), there was no significant change of riboflavin content in potatoes and cow peas. Based on a laboratory study, leaching was largely responsible for losses of these vitamins during water blanching, thermal processing and storage.     

Effect of thermal processing on available lysine,thiamine and riboflavin content in soymilk

Soymilk was heated over a range of temperatures (90–140°C) and times (0–6 h). The available lysine, thiamine and riboflavin content of the soymilk samples were determined. There was no significant change in available lysine during a 3 h heating period at 95°C. At elevated temperatures of 120 and 140°C, optimum heat processed soymilk gave higher measured values of available lysine than did soymilk processed at 95°C. Prolonged heating at 120 and 140°C caused a decline in available lysine. Kinetic data on the thermal degradation of thiamine and riboflavin in soymilk were fitted with first-order kinetics and the kinetic parameters were determined. © 1998 SCI.     

Vitamins in brewing: the impact of wort production on the thiamine and riboflavin vitamer content of boiled sweet wort

Wort production contains a number of processing steps that are aimed at the optimal extraction of nutrients from malt, including vitamins. This research revealed that the different wort production processing steps imposed different influences on the thiamine and riboflavin vitamer content of the final sweet wort. These vitamins play vital roles within yeast metabolism, where they act as enzyme cofactors. As such thiamine vitamers play a crucial role in many decarboxylating enzymes, while riboflavin vitamers play an integral role in energy production and redox maintenance. While mashing releases valuable starch into the liquor, both thiamine and riboflavin are also extracted. The extraction of these vitamins is the greatest at 65°C and is indirectly linked to the amylase activity. When the starches are broken down during mashing, the thiamine and riboflavin vitamers are gradually released into the mash liquor. The boiling and trub removal (whirlpool) processes impose losses in both vitamins owing to the high temperatures exhibited during these stages. While hop pellets were shown to contribute a small proportion of the vitamers studied, the use of kettle finings caused a significant reduction in both thiamine and riboflavin vitamers. Copyright © 2014 The Institute of Brewing & Distilling     

Mass Transfer in Strawberry Tissue During Osmotic Treatment I: Microstructural Changes

ABSTRACT: Microstructural changes in strawberry tissue were quantified during osmotic treatment (OT) with sucrose solutions in concentrations of 15 to 65 (% w/w). The response-surface method was used to determine how the process variables (processing time and concentration) influence cellular shrinkage and cell destruction. With regard to the concentration of the osmotic solution, the kinetics of cell destruction followed a 1st-order model. The diffusional approach for modelling water transport in a layer of cells inside the strawberry tissue showed that water diffusivity is related to the concentration of the sucrose solution. Water diffusivity ranged from 16 ± 2 10⁻¹² to 6.2 ± 0.6 10^12.2 m²/s with sucrose solutions in concentrations between 15 and 65 (% w/w).     

A quasi-chemical model for the growth and death of microorganisms in foods by non-thermal and high-pressure processing

Predictive microbial models generally rely on the growth of bacteria in laboratory broth to approximate the microbial growth kinetics expected to take place in actual foods under identical environmental conditions. Sigmoidal functions such as the Gompertz or logistics equation accurately model the typical microbial growth curve from the lag to the stationary phase and provide the mathematical basis for estimating parameters such as the maximum growth rate (MGR). Stationary phase data can begin to show a decline and make it difficult to discern which data to include in the analysis of the growth curve, a factor that influences the calculated values of the growth parameters. In contradistinction, the quasi-chemical kinetics model provides additional capabilities in microbial modelling and fits growth-death kinetics (all four phases of the microbial lifecycle continuously) for a general set of microorganisms in a variety of actual food substrates. The quasi-chemical model is differential equations (ODEs) that derives from a hypothetical four-step chemical mechanism involving an antagonistic metabolite (quorum sensing) and successfully fits the kinetics of pathogens (Staphylococcus aureus, Escherichia coli and Listeria monocytogenes) in various foods (bread, turkey meat, ham and cheese) as functions of different hurdles (a_w, pH, temperature and anti-microbial lactate). The calculated value of the MGR depends on whether growth-death data or only growth data are used in the fitting procedure. The quasi-chemical kinetics model is also exploited for use with the novel food processing technology of high-pressure processing. The high-pressure inactivation kinetics of E. coli are explored in a model food system over the pressure (P) range of 207–345 MPa (30,000–50,000 psi) and the temperature (T) range of 30–50 °C. In relatively low combinations of P and T, the inactivation curves are non-linear and exhibit a shoulder prior to a more rapid rate of microbial destruction. In the higher P, T regime, the inactivation plots tend to be linear. In all cases, the quasi-chemical model successfully fit the linear and curvi-linear inactivation plots for E. coli in model food systems. The experimental data and the quasi-chemical mathematical model described herein are candidates for inclusion in ComBase, the developing database that combines data and models from the USDA Pathogen Modeling Program and the UK Food MicroModel.     

Kinetics of Methylmethionine Sulfonium Salt Destruction in a Model Particulate System

The kinetics of methylmethionine sulfonium salt (MMS) degradation in a model food system during simulated aseptic thermal processing was investigated under controlled conditions for 1.27 cm side and 2.54 cm side sodium alginate cubes. To determine if concentration of MMS affected the kinetics as influenced by the cube geometry or composition, three concentration levels of MMS were investigated. The initial concentration of MMS in the particles, the particle size and particle shrinkage did not affect the reaction kinetics. The first order reaction rate constant for MMS destruction at 126.7°C was 0.15 min^?1 and the activation energy was 28.95 kcal/mole.     

A mechanism for sulphite ion reacting with vitamin B1 and its analogues

Sulphite ion has been shown to react by a multi-step mechanism with thiamine, 1'-methylthiaminium ion and various thiamine analogues. Sulphite ion replaces the thiazole-leaving group of a thiamine and a pyridine or a phenoxy group of an analogue. Sulphite ion first adds to the pyrimidinium ring, and this is followed by expulsion of the leaving group. The resultant cationic intermediate then reacts with a second sulphite ion; the observed pyrimidine substitution product forms after expulsion of the first sulphite ion. Although substitution is usually first order in the sulphite ion, the required second-order kinetics in sulphite ions have been demonstrated under special conditions. When the leaving group is a pyridine, the rate-limiting step is expulsion of the pyridine, but when the leaving group is a phenoxide ion, addition of the first sulphite ion is rate limiting. Hydroxide ion reacts with thiamine analogues by a similar multi-step mechanism. Second-order rate constants for hydroxide ion are slightly greater than those for sulphite ion. Sulphite ion is shown to be ‘special’ because it is a weak base, a strong nucleophile and a poor leaving group.