David M. Phinney

Effectiveness of Rinse Water during In-Place Cleaning of Stainless Steel Pipe Lines

UNLABELLED The 1st step of any Clean-In-Place (CIP) operation is a prerinse with water. The purpose of this step is to remove the bulk of food material remaining in the processing lines after production period has ended. It is known that this prerinse step can be a very water intensive process. The objective of this investigation was to measure the influence of CIP parameters (flow characteristics, water temperature, and contact time) on the effectiveness of prerinse water in removing dairy-based deposits from stainless steel pipe surfaces and to compare the rinse effectiveness of unused to reused rinse water. A pilot-scale CIP system was operated to rinse 304 stainless steel pipe sections of 3 different pipe diameters. The velocity of the rinse water was varied from 0.72 to 2.26 m/s. The rinse water temperatures were 22 °C, 45 °C, and 67 °C. The contact times between rinse water and deposited film were 20 and 60 s. Rinse effectiveness was expressed as the ratio of the amount of protein residue removed from the pipe surface during rinsing, as compared to the magnitude of the initial protein deposit. The rinse effectiveness varied from 73.1% to 94.9% for the range of the CIP parameters investigated. High velocities of rinse water provided a higher level of rinse effectiveness. Increasing the rinse water temperature from 23 °C to 45 °C improved rinse effectiveness significantly (P < 0.05). This impact was not significant when the water temperature was increased from 45 °C to 67 °C and at higher rinse water velocities. Similarly, longer contact time provided less improvement in rinse effectiveness at higher temperatures and velocities as compared to lower temperatures and velocities. There were no significant differences in rinse effectiveness when comparing reused and unused water (normal tap water) within the range of velocities evaluated. PRACTICAL APPLICATION The rinse steps are important components of the CIP operation and have direct impact on the amounts of water and energy used for the entire processing operation. The efficiency of rinse water can be improved significantly by the selection of appropriate combinations of operating parameters. For example, higher velocities of rinse water (2.26 m/s) provide significant improvements on rinse effectiveness when compared to current commercial practice (1.52 m/s). The careful selection of rinse water temperature and velocity can result in overall reductions in water and energy used for cleaning operations. The reuse of water for a 2nd or 3rd pass provides additional opportunities for reducing water requirements without influencing effectiveness.

Composition‐Based Prediction of Temperature‐Dependent Thermophysical Food Properties: Reevaluating Component Groups and Prediction Models

Prediction of temperature-dependent thermophysical properties (thermal conductivity, density, specific heat, and thermal diffusivity) is an important component of process design for food manufacturing. Current models for prediction of thermophysical properties of foods are based on the composition, specifically, fat, carbohydrate, protein, fiber, water, and ash contents, all of which change with temperature. The objectives of this investigation were to reevaluate and improve the prediction expressions for thermophysical properties. Previously published data were analyzed over the temperature range from 10 to 150 °C. These data were analyzed to create a series of relationships between the thermophysical properties and temperature for each food component, as well as to identify the dependence of the thermophysical properties on more specific structural properties of the fats, carbohydrates, and proteins. Results from this investigation revealed that the relationships between the thermophysical properties of the major constituents of foods and temperature can be statistically described by linear expressions, in contrast to the current polynomial models. Links between variability in thermophysical properties and structural properties were observed. Relationships for several thermophysical properties based on more specific constituents have been identified. Distinctions between simple sugars (fructose, glucose, and lactose) and complex carbohydrates (starch, pectin, and cellulose) have been proposed. The relationships between the thermophysical properties and proteins revealed a potential correlation with the molecular weight of the protein. The significance of relating variability in constituent thermophysical properties with structural properties--such as molecular mass--could significantly improve composition-based prediction models and, consequently, the effectiveness of process design.

Reverse Stability Kinetics of Meat Pigment Oxidation in Aqueous Extract from Fresh Beef

The use of kinetic models is an evolving approach to describing quality changes in foods during processes, including storage. Previous studies indicate that the oxidation rate of myoglobin is accelerated under frozen storage conditions, a phenomenon termed reverse stability. The goal of this study was to develop a model for meat pigment oxidation to incorporate the phenomenon of reverse stability. In this investigation, the model system was an aqueous extract from beef which was stored under a range of temperatures, both unfrozen and frozen. The kinetic analysis showed that in unfrozen solutions, the temperature dependence of oxidation rate followed Arrhenius kinetics. However, under in frozen solutions the rate of oxidation increased with decreasing temperature until reaching a local maximum around -20 °C. The addition of NaCl to the model system increased oxidation rates at all temperatures, even above the initial freezing temperature. This observation suggests that this reaction is dependent on the ionic strength of the solution as well as temperature. The mechanism of this deviant kinetic behavior is not fully understood, but this study shows that the interplay of temperature and composition on the rate of oxidation of meat pigments is complicated and may involve multiple mechanisms. PRACTICAL APPLICATION A better understanding of the kinetics of quality loss in a meat system allows for a re-examination of the current recommendations for frozen storage. The deviant kinetic behavior observed in this study indicates that the relationship between quality loss and temperature in a frozen food is not as simple as once thought. Product-specific recommendations could be implemented in the future that would allow for a decrease in energy consumption without a significant loss of quality.

Effect of solvent addition sequence on lycopene extraction efficiency from membrane neutralized caustic peeled tomato waste

Lycopene is a high value nutraceutical and its isolation from waste streams is often desirable to maximize profits. This research investigated solvent addition order and composition on lycopene extraction efficiency from a commercial tomato waste stream (pH 12.5, solids ∼5%) that was neutralized using membrane filtration. Constant volume dilution (CVD) was used to desalinate the caustic salt to neutralize the waste. Acetone, ethanol and hexane were used as direct or blended additions. Extraction efficiency was defined as the amount of lycopene extracted divided by the total lycopene in the sample. The CVD operation reduced the active alkali of the waste from 0.66 to <0.01M and the moisture content of the pulp increased from 93% to 97% (wet basis), showing the removal of caustic salts from the waste. Extraction efficiency varied from 32.5% to 94.5%. This study demonstrates a lab scale feasibility to extract lycopene efficiently from tomato processing byproducts.

Assessment of chicken breast meat quality after freeze/thaw abuse using magnetic resonance imaging techniques: Chicken meat MRI

BACKGROUND Freezing/thawing meat can result in quality losses as a result of the formation, melting and reformation of ice. These changes in water state can result in alterations in texture, water holding and other key quality attributes. It was hypothesized that magnetic resonance imaging (MRI) could quantify changes in mobility and localization of water as a function of freezing/thawing, which could be correlated with quality measurements. RESULTS Drip loss increased significantly for unbrined samples by over 100% after each freeze/thaw cycle (1.5% to 3.3% to 5.3% drip loss). Brine uptake decreased 50% after 2 cycles (from 53% to 28% mass uptake). Drip loss for brined samples increased after 2 cycles; other attributes were not significantly affected. MRI showed brined samples had less change in both proton density and T2 distributions. High-field nuclear magnetic resonance (NMR) imaging showed greater change in T2 distributions. CONCLUSION As freeze/thaw damage increased, meat quality was reduced in both brined and unbrined chicken breasts, with more prominent changes in unbrined meat. These decreases in quality correlated with changes, albeit small, in water mobility and localization as measured by MRI. High-field NMR micro-imaging showed more dramatic changes in T2 distributions in unbrined samples. These MRI techniques are shown to be useful in the assessment of meat quality after freeze/thaw abuse.

Prediction of Liquid Specific Heat Capacity of Food Lipids: Oil specific heat modeling…

Specific heat capacity (cp ) is a temperature dependent physical property of foods. Lipid-being a macromolecular component of food-provides some fraction of the foods overall heat capacity. Fats/oils are complex chemicals that are generally defined by carbon length and degree of unsaturation. The objective of this investigation was to use advanced specific heat capacity measurement to determine the effect of fatty acid chemical structure on specific heat capacity of food lipids. In this investigation, the specific heat capacity of a series of triacylglycerols were measured to quantify the influence of fatty acid composition on specific heat capacity based on two parameters; the -average carbon number (C) and the average number of double bonds (U). A prediction model for specific heat capacity of food lipids as a function of C, U and temperature (T) has been developed. A multiple linear regression to the three-parameter model (R2 = 0.87) provided a good fit to the experimental data. The prediction model was evaluated by comparison with previously published specific heat capacity values of vegetable oils. It was found that the model provided a 0.53% error, while three other models from the literature predicted cp values with 0.85% to 1.83% average relative deviation from experimental data. The outcomes from this research confirm that the thermophysical properties of fat present in foods are directly related to the physical chemical properties. PRACTICAL APPLICATION The specific heat capacity of food products is widely used in process design. Improvements of current models to predict specific heat capacity of food products will assist in the development of efficient processes and in the control of food quality and safety. Furthermore, the understanding of how changes in chemical structure of macromolecular components of foods effect thermophysical properties may begin to allude to models that are not just empirical, but represent portions of the differences in chemistry.

Effect of Freezing Rate and Microwave Thawing on Texture and Microstructural Properties of Potato (Solanum tuberosum)

Food freezing is a preservation process that works by lowering temperature while simultaneously decreasing water activity. It is accepted that although freezing preserves foods, it generally has a negative effect on textural quality. This research investigated the texture response of potatoes (Solanum tuberosum) as a function of time to freeze (defined as the time for the center temperature to reach -20 °C) and thawing process. Potatoes slices (6 mm) were blanched then frozen in an ethanol/carbon dioxide bath, a pilot scale high velocity air freezer (HVAF) and a still air freezer to achieve various times to freeze. Slices were stabilized at -20 °C and thawed by 2 methods; room temperature air and microwave. Afterwards, samples were allowed to come to room temperature prior to texture profile analysis (TPA). Results indicate a maximum texture loss of the potato was reached at a time to freeze of approximately 8 min (corresponding to the HVAF). The texture difference between room temperature and microwave thawing methods was not shown to be significant (P = 0.05). SEM images showed the cellular structure of the potato in a HVAF to be similar to that of the still air freezer, validating that the matrix was maximally damaged in both conditions. This work created a continuous quality loss model for the potato as a function of time to freeze and showed no textural benefit to high velocity over still air freezing.