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Growing consumer demand for clean-label “natural” products has encouraged more meat processors to cure meat products with natural sources of nitrate or nitrite such as celery juice powder. One challenge for these producers is to identify safe cooling rates in products cured with celery juice powder where extended cooling could allow growth of pathogens. The Food Safety and Inspection Service of the U.S. Department of Agriculture recently added guidelines for stabilization of meat products cured using naturally occurring nitrites based on control of Clostridium spp. However, a knowledge gap exists for safe cooling rates that prevent the growth of Listeria monocytogenes and Staphylococcus aureus, potential postlethality contaminants, in naturally cured ham. The study was conducted to investigate the temperature profiles of naturally cured hams of typical sizes during refrigerator cooling and to determine the behavior of S. aureus and L. monocytogenes on ham during these cooling periods. Whole hams (14 lb [6,300 g]), half hams (6 lb [2,700 g]), and quarter hams (3 lb [1,400 g]) were slowly cooked in a smokehouse until internal temperatures reached a minimum of 1408F (608C) and then were immediately transferred into a walk-in cooler (388F [3.38C]). Cooling times for hams of all sizes were within the requirements for cured products but not for uncured products. Worst-case scenarios of postprocessing surface contamination were simulated by inoculating small naturally cured ham samples with S. aureus or L. monocytogenes. These inoculated hams were then cooled under controlled conditions of 130 to 458F (54.4 to 7.28C) for 720 to 900 min. By the end of cooling, small decreases (0.5 to 0.6 log CFU/g) were found for each inoculum. These findings may help small ham processors evaluating production and quality control methods to determine whether recommended concentrations of natural curing agents used to prevent growth of clostridial pathogens may also prevent growth of other pathogens during meat cooling. Published (Publication status)

Bacterial exposure to stress, such as reduced water activity (aw), can increase thermal resistance. Pathogen thermal resistance studies on low-aw foods use a variety of methods to inoculate food, as well as strategies to reduce aw, which can influence observations. This study investigated effects of culture preparation method and osmolyte-induced aw on thermal resistance of two Shiga toxin-producing Escherichia coli (STEC) strains (O121:H19 and O157:H7) challenged with isothermal conditions, determining D- and z-values for each isolate (56, 59, and 62°C). Tryptic soy broth (TSB) and agar (lawn cultures) were compared. D-values of broth cultures were significantly and consistently larger than those of lawn cultures, and O121 was significantly more resistant than O157, but only at 56°C (P < 0.05). To compare potential effects of aw on STEC thermal resistance, cells were suspended in osmolyte solutions with varying aw: high (TSB, aw 0.99), intermediate (61% glycerol or 26% NaCl, aw 0.75), and low (82% glycerol, aw 0.5). In most instances, STEC strains in high-aw broth exhibited greater heat resistance compared to reduced-aw solutions, with the exception of the glycerol intermediate-aw solution (aw 0.75). Magnitudes varied with strain and temperature. The z-values of lawn cultures were significantly lower than those of broth cultures (P < 0.05), but there were few differences between high-aw and reduced-aw samples. There were no significant differences of z-values based on strain type. These results highlight that thermal resistance can be affected by culture preparation and that osmolyte-induced changes to aw influence thermal inactivation of STEC by varying magnitudes. These results emphasize the challenges of extrapolating results from laboratory inactivation kinetic experiments to determine the inactivation of low-aw foods, especially those considered dry in nature. HIGHLIGHTS

Consumers are becoming increasingly aware of the health benefits of dairy ingredients. However, products fortified with dairy proteins are experiencing considerable aroma challenges. Practices to improve the flavor quality of dairy proteins require a comprehensive understanding of the nature and origins of off-aroma. Unfortunately, existing information from the literature is fragmentary. This review presents sensory lexicons and chemical structures of off-aromas from major dairy ingredients, and it explores their possible precursors and formation mechanisms. It was found that similar chemical structures often contributed to similar off-aroma descriptors. Lipid degradation and Maillard reaction are two primary pathways that commonly cause aroma dissatisfaction. Traditional and novel flavor chemistry tools are usually adopted for off-aroma measurements in dairy ingredients. Strategies for improving aroma quality in dairy derived products include carefully selecting starting materials for formulations, and actively monitoring and optimizing processing and storage conditions. Published version

Salmonella, Shiga toxin-producing Escherichia coli (STEC), and Listeria monocytogenes have been isolated from low water activity foods (LWAF), where they may survive for extended periods. The ready-to-eat nature of many LWAF, such as dried fruits and nuts, warrants effective post-harvest thermal treatment for the reduction of pathogens such as low-temperature, saturated steam, also known as vacuum-assisted steam pasteurization. The objective of this study was to determine reductions of Salmonella, STEC, L. monocytogenes, and a possible surrogate (Pediococcus acidilactici) on dried apricot halves, whole macadamia nuts, and raisins after treatment with vacuum-assisted steam at three temperatures (62 °C, 72 °C, or 82 °C) and multiple time intervals. Bacterial inactivation was variable between commodities, with higher temperatures and longer times necessary to achieve comparable reductions of pathogens on apricot halves and macadamia nuts compared to raisins. Reductions of the tested pathogens were comparable; therefore, one species was not more resistant than the others. Pathogens were reduced by 5-log CFU/g on apricot halves after 20 min at 72 °C and after 5 min at 82 °C. Longer treatment times were necessary to achieve reductions of each pathogen on macadamia nuts. Pathogens were reduced by nearly 5 log CFU/g on macadamia nuts after 38 min at 72 °C (4.6–6.5 log CFU/g) and after 12 min at 82 °C (4.9–5.7 log CFU/g). Reductions of pathogens on raisins were achieved at lower temperatures than necessary for the other foods. A 5-log reduction for each of the pathogens (CFU/g) on raisins occurred after 20 min at 62 °C and after 5 min at 72 °C. Overall, the reductions of the pathogens exceeded those of P. acidilactici on both the dried fruits and macadamia nuts. Statistically significant differences, indicating greater confidence as a conservative surrogate, were observed at lower treatment temperatures. Inactivation kinetics were modeled for each pathogen on each food type and temperature. Bacterial survival was best described by the Weibull model for raisins and macadamia nuts, while the Gompertz model best described reductions on apricot halves according to Akaike information criterion (AIC) and root-mean-square error (RMSE) evaluations. Water activity and moisture content were increased due to the treatments, which could be addressed through implementation of drying steps. Thermal inactivation kinetic models and 5-log reduction parameters can help food processors design and evaluate similar vacuum-assisted steam interventions to comply with FSMA regulations and preventive control plans. However, results or model predictions should not be extrapolated to assume the safety of other types of foods.

Salmonellosis has been increasingly associated with contaminated spices. Identifying inoculation and stabilization methods for Salmonella on whole spices is important for development of validated inactivation processes. The objective of this study was to examine the effects of inoculation preparation on the recoverability of Salmonella enterica from dried whole peppercorns and cumin seeds. Whole black peppercorns and cumin seeds were inoculated with S. enterica using one dry transfer method and various wet inoculation methods: immersion of spice seeds in tryptic soy broth (TSB) plus Salmonella for 24 h (likely leading to inclusion of Salmonella in native microbiota biofilms formed around the seeds), application of cells grown in TSB, and/or application of cells scraped from tryptic soy agar (TSA). Postinoculation seeds were dried to a water activity of 0.3 within 24 h and held for 28 days. Seeds were sampled after drying (time 0) and periodically during the 28 days of storage. Salmonella cells were enumerated by serial dilution and plated onto xylose lysine Tergitol (XLT4) agar and TSA. Recovery of Salmonella was high after 28 days of storage but was dependent on inoculation method, with 4.05 to 6.22 and 3.75 to 8.38 log CFU/g recovered from peppercorns and cumin seeds, respectively, on XLT4 agar. The changes in surviving Salmonella (log CFU per gram) from initial inoculation levels after 28 days were significantly smaller for the biofilm inclusion method (z0.142pepper, z0.186cumin) than for the other inoculation methods (20.425pepper, 22.029cumin for cells grown on TSA; 20.641pepper, 20.718cumin for dry transfer; 21.998pepper for cells grown in TSB). In most cases, trends for reductions of total aerobic bacteria were similar to those of Salmonella. The inoculation method influenced the recoverability of Salmonella from whole peppercorns and cumin seeds after drying. The most stable inoculum strategies were dry transfer, 24-h incubation of Salmonella and spices in TSB (i.e., potential inclusion of Salmonella within native microbiota biofilms), and inoculation of Salmonella cells grown on TSA subsequent to drying. However, with the dry transfer method it was difficult to obtain the large amount of inoculum needed for inactivation studies. Published version This article was submitted using Open Access

The effects of packaging treatments, postharvest cooling delay and storage duration on color, texture, ascorbic acid content, weight loss and glucosinolate retention in crown-cut heads of broccoli were studied. Broccoli stored in shrink wrap film lost 3.7% of its original weight, whereas ice packaging resulted in 17.4% weight loss during storage. Long postharvest cooling delay and storage duration negatively affected broccoli color. Broccoli heads stored in shrink wrap packaging retained firmness longer than broccoli stored in ice. Ascorbic acid retention was improved in shrink wrapped broccoli, but retention decreased as postharvest cooling delay and storage duration lengthened. Shrink wrapped broccoli exhibited improved retention of the glucosinolate, glucoraphanin. During storage, “Gypsy” broccoli maintained better quality than “Everest” with respect to color, ascorbic acid retention and weight loss. However, “Everest” retained texture (firmness) better after 35 days of storage. Shrink wrap packaging and shorter postharvest cooling delays preserve broccoli quality and increase shelf life. PRACTICAL APPLICATIONS Broccoli has the potential to be a high value crop if the shrink wrap packaging technology can be disseminated to the broccoli growers. Typically, farmers use ice for cooling broccoli heads after harvest, which is an expensive and difficult practice. Without icing requirement, broccoli marketing will be easy and opens up significant potential for broccoli producers who can afford relatively inexpensive film wrapping machines (as compared with ice equipment) in conjunction with onsite cooling. Sometimes onsite cooling is not possible and delays may be involved before the harvested produce is cooled. The conclusions reached in this study shows that shrink wrap packaging can be used to improve quality, retain phytochemical content and prolong the shelf life of crown-cut broccoli.

Type of thermal process [high temperature, short time pasteurization (HTST) or ultra-high temperature pasteurization (UHT)] and homogenization sequence (before or after pasteurization) were examined for influence on the physicochemical properties of natural cream (20% milk fat) and creams formulated with 20% low-melt, fractionated butteroil emulsified with skim milk, or buttermilk and butter-derived aqueous phase. Homogenization sequence influenced physicochemical makeup of the creams. Creams homogenized before pasteurization contained more milk fat surface material, higher phospholipid levels, and less protein at the milk fat interface than creams homogenized after pasteurization. Phosphodiesterase I activity was higher (relative to protein on lipid globule surface) when cream was homogenized before pasteurization. Creams formulated with skim milk and modified milk fat had relatively more phospholipid adsorbed at the milk fat interface. Ultra-high-temperature-pasteurized natural and reformulated creams were higher in viscosity at all shear rates investigated compared with HTST-pasteurized creams. High-temperature, short time-pasteurized natural cream was more viscous than HTST-pasteurized reformulated creams at most shear rates investigated. High-temperature, short time-pasteurized creams had better emulsion stability than UHT-pasteurized creams. Cream formulated with buttermilk had creaming stability most comparable to natural cream, and cream formulated with skim milk and modified butteroil was least stable to creaming. Most creams feathered in a pH range of 5.00 to 5.20, indicating that they were moderately stable to slightly unstable emulsions. All processing sequences yielded creams within sensory specifications with the exception of treatments homogenized before UHT pasteurization and skim milk formulations homogenized after UHT pasteurization.

Dairy systems formulated with fractionated milkfat and milk-derived components have compositional differences that may affect functionality and nutritional aspects as compared to natural dairy products. The composition of 20% milkfat creams formulated with emulsifying components (skim milk, sweet buttermilk, and butter-derived aqueous phase) and low- or medium-melt fractionated butteroil was compared with natural cream. Cream separation temperatures (49 and 55 degrees C) and processing conditions (commercial and pilot plant) in obtaining emulsifying components were examined for effect on content of surface active agents. Individual fatty acids, lipids, cholesterol, phospholipids, protein levels, and types varied with components. Separation temperature influenced the cholesterol level in the aqueous phase. A commercially produced aqueous phase contained less total lipid, protein, cholesterol, and phospholipid than aqueous phase obtained in the pilot plant. Milkfat globule membrane concentration of emulsifying components affected phospholipid and cholesterol content of formulated creams. Butteroil type affected cholesterol levels and cream formulations.

Emulsifying properties of milk-derived components influence the physical characteristics of reformulated creams. Fractionated butter oils with different melting ranges (low-melt: 10 to 25 degrees C; medium-melt: 25 to 35 degrees C) were recombined into fluid dairy systems using skim milk, or sweet buttermilk and butter-derived aqueous phase to manufacture 20% milk fat creams. Separation temperature (49 degrees C or 55 degrees C) in obtaining emulsifying components was examined for its effect on physical properties of pasteurized reformulated creams. Rate of creaming, viscosity, feathering, and sensory characteristics of reformulated and natural creams stored at 3.3 degrees C were evaluated over a 13-d period. Creaming rate of reformulated and natural creams was unaffected by formulation and was most influenced by duration of storage. Melting characteristics of butter oils influenced viscosity at some shear rates. With the exception of natural cream, all formulations were consistent in apparent viscosity during the 2-wk storage period. All creams feathered in a pH range of 4.70 to 5.20 and were classified as moderately stable to slightly unstable. All reformulated and natural creams met sensory quality specifications with the exception of creams formulated with skim milk and lower melting range butteroil. Creams formulated with buttermilk, butter-derived aqueous phase, and lower-melting range butter oil most closely mimicked natural creams with regard to sensory quality and viscosity.