All Treatment Parameters Affect Environmental Surface Sanitation Efficacy, but Their Relative Importance Depends on the Microbial Target.

Environmental sanitation in food manufacturing plants promotes food safety and product microbial quality. However, the development of experimental models remains a challenge due to the complex nature of commercial cleaning processes, which include spraying water and sanitizer on equipment and structural surfaces within manufacturing space. Although simple in execution, the physical driving forces are difficult to simulate in a controlled laboratory environment. Here, we present a bench-scale bioreactor system which mimics the flow conditions in environmental sanitation programs. We applied computational fluid dynamic (CFD) simulations to obtain fluid flow parameters that better approximate and predict industrial outcomes. According to the CFD model, the local wall shear stress achieved on the target surface ranged from 0.015 to 5.00 Pa. Sanitation efficacy on six types of environmental surface materials (hydrophobicity, 57.59 to 88.61°; roughness, 2.2 to 11.9 µm) against two different microbial targets, the bacterial pathogen Listeria monocytogenes and Exophiala species spoilage fungi, were evaluated using the bench-scale bioreactor system. The relative reduction ranged from 0.0 to 0.82 for Exophiala spp., which corresponded to a 0.0 to 2.21 log CFU/coupon reduction, and the relative reduction ranged from 0.0 to 0.93 in L. monocytogenes which corresponded to a 0.0 to 6.19 log CFU/coupon reduction. Although most treatment parameters were considered statistically significant against either L. monocytogenes or Exophiala spp., contact time was ranked as the most important predictor for L. monocytogenes reduction. Shear stress contributed the most to Exophiala spp. removal on stainless steel and Buna-N rubber, while contact time was the most important factor on HDPE (high-density polyethylene), cement, and epoxy.IMPORTANCE Commercial food manufacturers commonly employ a single sanitation program that addresses both bacterial pathogen and fungal spoilage microbiota, despite the fact that the two microbial targets respond differently to various environmental sanitation conditions. Comparison of outcome-based clusters of treatment combinations may facilitate the development of compensatory sanitation regimes where longer contact time or greater force are applied so that lower sanitizer concentrations can be used. Determination of microbiological outcomes related to sanitation program efficacy against a panel of treatment conditions allows food processors to balance tradeoffs between quality and safety with cost and waste stream management, as appropriate for their facility.

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

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. © 2018 Society of Chemical Industry.

Prediction of Liquid Specific Heat Capacity of Food Lipids.

Specific heat capacity (cp ) is a temperature dependent physical property of foods. Lipid-being a macromolecular component of food-provides some fraction of the food's 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.

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.

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.