Sibel Ozilgen

Thermal design calculations for food freezing equipment-past, present and future

Abstract The literature on methods for thermal design of food freezing equipment is reviewed with emphasis on two questions: what do those who design, build and commission freezers most need from researchers in terms of improved design calculation methods, and what are the most limiting factors in determining whether a particular freezer design will satisfactorily freeze the product at the required throughput rate? Freezing time prediction methods have been significantly improved over the last two decades and are now infrequently the factor most limiting accurate design. There is a much greater need for more accurate thermophysical properties and better information on heat transfer coefficients for a variety of practical situations. The failure of many industrial freezers to deliver the design conditions to product in all parts of the freezer is also important. Future research should address the full range of factors limiting accurate freezer design, which may mean less emphasis on freezing time prediction.

Improvement of the safety of the red pepper spice with FMEA and post processing EWMA quality control charts

Although there are numerous decades-old studies drawing attention to the presence of aflatoxins in spices, and particularly in red pepper spice, the problem has not been eradicated. In the present study, information presented in the literature, about production method of red pepper spice, its contamination with aflatoxin, and the uncertainty about the data are assessed to find out the points where improvement may be achieved. Failure Mode and Effect Analysis (FMEA) are performed to assess the risk. The highest total risk attributable to chemical plus physical plus biological causes is associated with the washing stage (RPN=363), which is followed by the receiving (RPN=342) and the storage (RPN=342) stages. The highest risk attributable to biological causes (RPN=180) is associated with microbial growth and aflatoxin production due to insufficient control of drying conditions. The highest chemical risk (RPN=144) is found for the presence of unintentional food additives, such as pesticides, herbicides, hormones, and heavy metals in fresh red pepper fruits. EWMA (exponentially weighted average) charts are employed to monitor aflatoxin production during storage. They successfully distinguished between the batches, which turned to be unsafe. Risk associated with unintentional additives may be reduced by using certified additives only. Better drying control will definitely reduce the risk associated with the drying process. Codex Alimentarius plan has worldwide acceptance for assessing safety of the nuts. Risk of accepting the batches contaminated with aflatoxin may be eliminated by applying the Codex Alimentarius sampling plan before putting the dry pulverized red pepper into the storage facility.

Kinetic compensation relations: Tools for design in desperation

Compensation relations are obtained for previous studies while assessing whether the compensation phenomena is real or merely a mathematical artifact. Equations concerning compensation from food and bioengineering researchers from the literature are examined as to their possible use as a tool in process design with missing data. Computer flow diagrams are given to explain this procedure and two worked sample sets of data are given as examples.

A model for pasteurization with microwaves in a tubular flow reactor

Abstract Thermal death kinetics of Escherichia coli with microwaves were studied by using a tubular flow reactor with different diameters, lengths, and flow rates. Mathematical models were presented for temperature profile development and death of the microorganisms along the reactor. A first-order kinetic expression in biomass concentration simulated the death phenomena. Temperature effects on the death rate constant were expressed with an Arrhenius expression. Numerical values of the constants of this expression were found to be considerably different in microwave pasteurization experiments from those of the experiments with a constant temperature water bath. These constants were also affected by the average velocity of the medium in the reactor. Apparent death rate constants were higher with the microwave pasteurization experiments than those of the constant temperature water bath experiments at low temperatures. The results implied that tubular flow reactors may be efficiently used, especially in low-temperature pasteurization and sterilization processes.

Application of failure mode and effect analysis model to foodservice systems operated by chefs in practice and by chefs from a culinary school in Turkey

Failure mode and effect analysis (FMEA) methodology has been applied for the risk assessment of basic foodservice systems operated by the “chefs in practice” and by the “chefs from a culinary school” in Turkey. Firstly, the preliminary hazard analysis was done to predict the potential failure modes in the food flow of basic foodservice systems. Each step in the process, from receiving of raw ingredient to table, was analyzed. The risk priority numbers (RPN) were calculated for each failure mode. The corrective actions were suggested to lower the RPN values below the acceptable limit of 120. The data collected in this study compared to the data from a study carried out with “chefs in practice” about basic food safety issues. The significant difference was observed between “the chefs in practice” and “the chefs with formal culinary education”. Majority of chefs from a culinary school have scored better in many food safety issues, so thus the corrective actions in the FMEA table. The results clearly point out the urgent need for FMEA integration and for food handler education in current foodservice establishments in Turkey.

General Template for the FMEA Applications in Primary Food Processing

Data on the hazards involved in the primary steps of processing cereals, fruit and vegetables, milk and milk products, meat and meat products, and fats and oils are compiled with a wide-ranging literature survey. After determining the common factors from these data, a general FMEA template is offered, and its use is explained with a case study on pasteurized milk production.

Functional Biopolymers in Food Manufacturing

Abstract Food hydrocolloids are high molecular weight long-chain biopolymers. They are made of high molecular weight polysaccharides and proteins. Hydrocolloids are widely used as functional food additives in many food products to keep or improve the sensory attributes of the foods and drinks, to improve the shelf life of the food products, to make the production processes easier and more efficient, and to produce functional food products. The key focus of this chapter is the hydrocolloids themselves, including the fundamental discussion of the research findings and their significance. The main areas of the interest are chemical and physicochemical characterization of hydrocolloids, their rheological properties including viscosity, viscoelastic properties and gelation behavior, their interfacial properties, including stabilization of food colloids, their influence on sensory properties of food products, their film-forming properties with application to edible films and active packaging, their encapsulation properties, and their applications in the food industry as food additives and health promoters. Functional properties and the relation between the functional properties and the nanostructures of bacterial polysaccharides (e.g., xanthan, cellulose), plant/algal polysaccharides (e.g., starch, agar, alginate, pectin), and animal polysaccharides (e.g., chitosan), and their primary applications in the food industry are covered in this chapter.