Ham Mite Research Articles

Uses and commercialization of food grade and effectiveness of coated ham nets to combat Tyrophagus putrescentiae: a review

Since the 1930s, the dry-cured ham industry has used methyl bromide fumigation to control Tyrophagus putrescentiae (ham mite) infestations. However, due to methyl bromide being a class I ozone depleting substance and no longer being manufactured, alternatives to methyl bromide have been studied extensively. Direct contact food-grade coatings and coated ham nets of various materials have shown efficacy in controlling ham mite growth and reproduction. These coated nets, often including propylene glycol, can be dried to ease application and reduce shipping cost, but chemical and thermal treatments on fabrics may cause the fabrics to become more brittle, which negatively impacts stretchability and bursting strength, and ultimately the effectiveness of the net. Scanning electron microscopy can provide precise visual inspection of fabric surface morphology, allowing for a detection of potential damage to the fibers. This purpose of this review is to summarize the application of food-grade coatings on nets used in the dry-cured ham industry to control mite infestations. More importantly, the review provides comprehensive information on coated nets, covering various aspects such as the selection of netting materials, evaluation of fabric properties, techniques for coating nets, net drying method, all in relation to their efficacy for mite control. This review contributes to the broad area of this applied technology by highlighting efficacious treatments to control mites, ineffective treatments, a discussion of processes to evaluate their properties, and future prospectives regarding this area of study.

Efficacy of a carboxymethylcellulose (CMC)-based edible film with propylene glycol to control ham mite populations that infest dry cured ham

Dry-cured hams are susceptible to ham mite, Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae), infestations during the aging process. Methyl bromide (MB) fumigation has been used to control mites from infesting hams. However, MB is an ozone depleting substance that is both expensive and scarce, so alternative control methods must be discovered. The objective of this research was to determine the efficacy of using an edible film to control or reduce mite growth and reproduction on dry-cured hams. The edible films consist of water, 1% of carboxymethylcellulose (CMC), and propylene glycol (PG), which was included at five concentrations: 0%, 5%, 10%, 15%, and 20%. The resulting films’ ability to reduce mite infestation was tested against two control groups: exposed ham cubes (negative control) and ham cubes wrapped in polyester nets (positive control) containing 40% PG, 1% carrageenan, and 1% propylene glycol alginate. Two weeks after inoculation with 20 mites, all film treatments had fewer (P < 0.05) mites than the negative control (262-mites). Film treatments with 0% (24-mites), 5% (26-mites), and 10% PG (17 mites) were effective at slowing mite reproduction, but not to the extent of the positive control (0-mites), 15% (6-mites), and 20% (1-mite) PG films as evidenced by a linear decrease in mite counts (F1 = 19.22, P < 0.0001) as PG concentration increased. Water Vapor Transmission (WVT) and Oxygen Permeability (OP) results indicated that all films exhibited substantial breathability with values ranging from 805 g m−2 day−1 to 899 g m−2 day−1 for WVT and 355 cc m−2 day−1 to 3413 cc m−2 day−1 for OP. Sensory analysis results indicated that the film treatments did not alter the sensory properties of the treated hams when compared to the untreated control. Further studies will include application of films to whole hams during aging and improved manufacturing techniques for films.

Efficacy of the Fumigants Propylene Oxide and Ethyl Formate to Control Two Pest Species of Dry-Cured Hams

The ham mite Tyrophagus putrescentiae and the red-legged ham beetle Necrobia rufipes are harmful pests to several high-valued stored products. The regulatory phase-out of the fumigant methyl bromide necessitates the search for alternative fumigants. Propylene oxide (PPO) and ethyl formate (EF) were therefore evaluated in the laboratory for controlling these pests of dry-cured hams. Concentration–mortality studies at 25 °C of PPO and EF found that the mobile stages of the mites were very susceptible to low concentrations of 10 mg/L and less of each gas, while mite eggs were very tolerant and required 20 mg/L for PPO and 80 mg/L of EF for 100% mortality. Mixed life stage cultures of mites and beetles were treated for 24 h with either PPO or EF at 1× and 2× the estimated 99% lethal doses and confirmed effectiveness for controlling simulated pest populations. The sorptive properties of each gas in chambers with ham pieces, dog food kibbles, or fish meal were minimal for a reduction in mite toxicity when compared to treatments in empty chambers. There was no evidence that any desorbed gas occurred at a level toxic to mite eggs in any of the fumigated commodities. These fumigation studies with ham pests support further work with PPO and EF on any changes in the sensory quality of dry-cured hams for human taste and for commercial-scale fumigations toward regulatory approval.

Using liquid smoke to control infestations of the ham mite, Tyrophagus putrescentiae, on dry-cured hams during aging

Eight treatments of edible coatings and nets including liquid smoke (SP and 24P) and xanthan gum (XG) were used to evaluate their effectiveness at controlling mite growth on dry-cured hams. Mite growth was controlled (P < 0.05) in both coating and netting treatments of 1% SP + 1% XG. Increasing SP concentration from 1% to 2% in the SP only treatments without XG did not control mite growth (P > 0.05) in the coating but controlled mite growth (P < 0.05) when infused in the nets. Both coating and netting treatments with 2% 24P + 1% XG controlled mite growth (P < 0.05), and ham cubes with 1% and 2% 24P in infused nets had mite numbers of 4.6 and 9.4, respectively. SP did not impact the sensory attributes of the ham. Results indicate that liquid smoke can potentially be added in coatings or ham nets to control mites and used in an integrated pest management program for dry-cured hams.

Effectiveness of nets treated with food-grade coatings following various drying methods for controlling mite growth on dry-cured hams

Tyrophagus putrescentiae (Schrank), commonly referred to as the ham mite, may infest dry-cured pork during aging. Food-grade propylene glycol (PG) coated ham nets inhibit mite growth and reproduction, but there are application challenges, including shipping costs and handling. Therefore, the objective of this research aimed was to determine if the food-grade coating treated ham nets were still effective at controlling mite growth after drying. Using previously developed methods, polyester nets were coated with a food-grade solution of 40% PG, 1% propylene glycol alginate, and 1% carrageenan. Six treatments were evaluated: no net (NC), coated and wet net (WC), uncoated net (UC), oven-dried for 7 min at 93.3 °C (OD7m), oven-dried for 20 min at 93.3 °C (OD20m), and counter-dried at 22-23 °C for 24 h (CD24h). Ham cubes (2.5cm × 2.5cm × 2.5 cm) were wrapped in the nets (n = 5/trt) and inoculated with 20 adult mites. The cubes were stored in ventilated jars at 25 °C and 70% relative humidity for 14 d. Mites on each ham cube were counted after the 14 d incubation period. A randomized complete block design was used to determine if differences existed (P ≤ 0.05) among treatments. Duncan's multiple range test was used to separate treatment means when differences existed. The OD7m, CD24h, and WC treatments had fewer mites (P ≤ 0.05) than the OD20m and UC treatments; the C treatment had the greatest (P ≤ 0.05) mite count. The OD7m and CD24h treatments lost 37.3% and 36.5% of their starting weights, respectively, while OD20m lost 72.0%. The greater loss (P ≤ 0.05) for the OD20m treatment may have affected the treatment's efficacy. In addition, drying coated nets did not affect the mechanical quality of nets nor the sensory quality of hams when they were wrapped in dried coated nets.

Nitric Oxide Fumigation for Control of Ham Mite, Tyrophagus putrescentiae (Sarcoptiformes: Acaridae).

The ham mite, Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae), is a common pest infesting several stored products, particularly the aged hams. In this study, we reported the efficacy of nitric oxide (NO) fumigation, a recently discovered fumigation treatment under the ultra-low oxygen environment, at various concentrations and time under the laboratory conditions at 25°C against different mite stages on both dietary media and ham meat. Our results showed that NO fumigation was effective against all mite stages and 100% control was achieved. Generally, the egg was the most tolerant stage and required 48-, 24-, 16-, and 8-h treatments to achieve 100% mortality at 0.5, 1, 1.5, and 2% NO concentration on dietary media, respectively. Tyrophagus putrescentiae mobile immatures and adult stages were less tolerant, and 100% mortality was achieved after 16-, 8-, 8-, and 4-h treatment at 0.5, 1, 1.5, and 2% NO, respectively. The median lethal concentration (LC50) of NO on egg was 0.86, 0.68, and 0.32% for 8-, 16-, and 24-h treatments. In addition, a confirmatory test was conducted on ham meat at 0.5 and 1.0% of NO and similar efficacy was found. Complete control of egg was achieved after 48- and 24-h treatment at 0.5 and 1.0% of NO, respectively, and larvae and adult mites were 100% controlled after 16 and 8 h at 0.5 and 1.0% of NO, respectively. Our results demonstrated that NO fumigation was effective against T. putrescentiae and can be a potential alternative treatment to methyl bromide for cured-ham pest control.

The Application of Food-Grade Chemical Treatment and Its Effect on the Mechanical Performance Characteristics of Ham Nets

This study involves the use of food-grade chemicals in the integrated pest management of dry-cured ham through the use of 100% polyester weft knitted mesh nets, an idea that was derived from a previously published study in the literature. Tubular mesh nets that are used to contain dry-ageing hams, commonly referred to as ham nets, were treated with a patent-pending food-grade chemical solution (40% Propylene Glycol + 1% Propylene Glycol Alginate + 1% Carrageenan) to control ham mites. Both treated and untreated ham nets were compared for mechanical performance characteristics based on the following standards: abrasion resistance (ASTM D4966), elastic recovery (BS EN 14704-1:2005), breaking strength (ASTM D5034-09), and bursting strength (ASTM D3786). The results indicate that the chemical treatment had minimal to no impact on the mechanical performance characteristics of ham nets. The obtained SEM images also showed no negative effect on the fiber morphology due to the applied chemical solution. The findings support the use of treated ham nets to increase the end-use functionality and provide ham producers an option for integrated pest management without compromising mechanical performance needs.

Natural and Synthetic Repellents for Pest Management of the Storage Mite Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae).

Simple SummaryThe ham mite is the major pest of dry-cured hams, aged cheeses, and specialty pet foods that are high in fats and proteins. Ham mites are also known to cause allergies in some cases for humans. The toxic fumigant gas methyl bromide had been used for years to control this mite pest, but it is being phased out of use due to its impact on the protective ozone layer of the earth’s upper atmosphere. Ham producers now require alternatives to methyl bromide for controlling mites. We conducted laboratory experiments with food-safe synthetic and plant-derived chemical repellents to keep mites away from dry cured hams. Our results showed that several of these repellents could effectively prevent ham mites from contacting and staying on treated pieces of ham, and that they would readily go to untreated ham pieces when given a choice. Further experiments found that mites would not feed on nor produce offspring when held on ham pieces coated with oils from thyme, lemon grass, rose, or a mixture of naturally occurring fat molecules. Our experiments suggest that these food-safe repellents might protect dry-cured hams from mites during their time in aging rooms by application to racks on which hams are aged or to the nets and packaging in which hams are held.The fumigant pesticide methyl bromide (MB) was used for stored products, but it is now banned for most uses in many countries as an ozone-depleting substance. MB was the only pesticide used to manage the ham mite, Tyrophagus putrescentiae, which is the most significant pest of dry cured hams. Effective alternatives to MB are needed to develop integrated pest management (IPM) programs for this pest. This study evaluated plant essential oils and food-safe compounds as repellents to directly protect hams from infestation. Experiments to assess the repellency to orientation, oviposition, and population growth of mites on pieces of aged country hams were conducted. Test compounds at different concentrations were dissolved in respective solvents and compared to the solvent control. Results showed that C8910, a mixture of three short-chain fatty acids, and the sesquiterpene ketone nootkatone had repellency indices of (RI) of 85.6% and 82.3%, respectively, at a concentration of 0.1 mg/cm2, when applied to a Petri dish arena. DEET and icaridin were also tested but performed poorly with RIs below 70% even at 0.1 mg/cm2.The monoterpene alcohol geraniol had the highest RI of 96.3% at 0.04 mg/cm2. Ham pieces dipped in C8910 and nootkatone at 150 ppm each had RIs of 89.3% and 82.8%, respectively. In general, as the concentrations of test compounds increased, the numbers of eggs that were laid on these treated ham cubes decreased after the 48 h exposure time. Ham pieces dipped in different concentrations of test compounds and then inoculated with 20 adult mites showed a significant decrease in mite population growth compared to control pieces after 14 days. The results of these experiments suggest that some plant secondary metabolites and synthetic food-safe compounds could serve as potential alternatives for managing mites on hams.

Tyrophagus putrescentiae (Sarcoptiformes: Acaridae) in the in vitro cultures of slime molds (Mycetozoa): accident, contamination, or interaction?

Tyrophagus putrescentiae (Schrank), commonly known as the cereal mite, cheese mite, or ham mite, is a cosmopolitan species reported from various environments in the wild, including soil, plant material and vertebrate nests. It has also been recognized as a common pest of food storages, mycological collections as well as plant and invertebrate laboratory cultures. Laboratory observations indicate that T. putrescentiae feeds on a large range of dermatophytes, yeasts and molds. We have observed the interspecific relation between this mite and several species of true slime molds (Mycetozoa) under laboratory conditions, which confirms the very broad spectrum of feeding habits of T. putrescentiae. Mycetozoans were grown in semi-sterile in vitro cultures and fed with oat flour or oat flakes. Tyrophagus putrescentiae displayed affinity to all macroscopically identifiable stages of the life cycle of Fuligo septica (L.) F.H. Wigg, Physarum polycephalum Schwein and the Didymium sp. complex [Didymium iridis (Ditmar) Fr., Didymium nigripes (Link) Fr. and Didymium bahiense Gottsb.]: live, decaying or dead plasmodia, sporangia, aethalia, spores and sclerotia. The relation carrying symptoms of various types of interspecific interaction, is hypothesized to form an evolutionarily young phenomenon, which not only identifies a new aspect of mycetozoal biology, but also presents the cereal mite as a species of high adaptive potential.

Sulfuryl fluoride as a methyl bromide alternative for fumigation of Necrobia rufipes (Coleoptera: Cleridae) and Tyrophagus putrescentiae (Sarcoptiformes: Acaridae), major pests of animal-based stored products

Sulfuryl fluoride (SF) has been registered in many countries for stored product applications as an alternative to other fumigants, especially methyl bromide (MB). Research was conducted to establish SF fumigation protocols for the mortality of pests infesting post-harvest durable commodities. The efficacy of SF against two major arthropod pests of southern dry-cured hams, the red-legged ham beetle, Necrobia rufipes, and the ham mite, Tyrophagus putrescentiae, was investigated. SF caused significant mortality in ham beetles but not for ham mites when treated for 48 h at 23 °C. Eggs of N. rufipes were more tolerant to SF than other stages fumigated. In addition, early aged (1–2 d old) eggs of N. rufipes were more susceptible to SF than late-aged (4–5 d old) eggs. Furthermore, SF fumigation led to 100% control of larvae, pupae and adults of N. rufipes by 8 g/m3 while the eggs required 20.88–24.72 g/m3 to prevent 100% hatch. However, T. putrescentiae showed high tolerance to SF as it survived concentration-time products in excess of the standard label limit 1500 g h/m3. SF studies also revealed that the eggs of T. putrescentiae were several fold more tolerant than that of the mobile stage, the nymphs and adults. SF trials under pilot-scale commercial conditions were also carried out that further supported the efficacy of SF for red-legged ham beetles but not for the ham mite. SF may not be suitable for managing ham mites based on work to date, but future work could investigate longer exposure times at higher temperatures.

The application of food grade short chain fatty acids to prevent infestation of Tyrophagus putrescentiae on dry cured ham and the effects on sensory properties

Tyrophagus putrescentiae (ham mite) is difficult for commercial dry cured ham producers to control. Methyl bromide is an effective fumigant but is now banned as an ozone depleting substance, meaning alternative methods to control mite infestation must be found. This research was conducted to test the efficacy of C8C9C10 fatty acids combined with and without food grade coatings to control mite infestations on dry cured hams. Ham cubes were coated directly or wrapped in nets saturated with C8C9C10 with combinations of either soybean oil, xanthan gum (XG) or carrageenan (CG) + propylene glycol alginate (PGA). Cubes were then inoculated with 20 large mixed sex ham mites and stored for 14 days at 22 ± 2 °C and 70 ± 5% relative humidity. The soybean oil alone or in combination with 10% C8C9C10 in direct coating, and 1% and 10% C8C9C10 in coated nets controlled mite population growth. In addition, the use of 10% C8C9C10 + XG and 10% C8C9C10 + CG + PGA in direct coatings or in saturated nets, and 1% C8C9C10 + XG in saturated nets also inhibited mite population growth. Unexpectedly, the soybean oil solvent by itself effectively controlled mite population growth as well. Sensory evaluation was performed using a difference from control test (n = 8) and indicated that only 10% C8C9C10 mixed with soybean oil and 100% soybean oil did not impart sensory differences to ham when used as a coating. However, for ham slices treated in saturated nets and gum with C8C9C10 mixtures in either coating or saturated nets did impart sensory differences. Results indicated that C8C9C10 and soybean oil could be used in coating formulations to control ham mites but long-term testing, sensory evaluation, and scaled up testing is needed prior to industrial implementation.

The effects of dry-cured ham initial water activity on Tyrophagus putrescentiae infestations

A 5 × 2 × 2 factorial arrangement within a completely randomized design was used to evaluate the effect of aw (0.65, 0.70, 0.75, 0.80, and 0.85), RH (65% and 75%) and temperature (24 °C and 28 °C) on Tyrophagus putrescentiae growth, on ham cubes in two separate experiments, one for treated nets (infused with propylene glycol (PG) + propylene glycol alginate (PGA) + carrageenan (CG) + water) and one for untreated control nets. For treated nets, water activity and temperature did not affect mite growth. When control nets were used, there was no difference due to aging temperature, but there were more mites (P < 0.05) at 65% RH than at 75% RH. In addition, ham cubes with 0.85 aw had more mites (P < 0.05) than at 0.70 and 0.65 aw, and ham cubes with 0.80 and 0.75 aw had more mites (P < 0.05) than at 0.65 aw. The only treatment combinations that controlled mites were the ham cubes with 0.65 aw that were stored at 75% RH at both temperatures, with average mite counts below the initial inoculum level of 20 mites. Overall, results indicated that the treated nets were effective at controlling ham mites, regardless of ham cube aw, storage temperature, and RH. However, if only untreated barrier nets were used, mites were only controlled when ham cubes had a aw of 0.65 or 0.70 and were stored at 75% RH. These conditions may not be practical since drying to 0.65 or 0.70 aw would result in more moisture loss, lower yields, and less product that could be sold.

Acaricidal effects of fresh garlic juice on adult ham mite, Tyrophagus putrescentiae (Schrank)

Ham mites, Tyrophagus putrescentiae (Schrank), are a common pest of dry cured meat products and cause devastating effects on product quality. Methyl bromide, a chemical fumigant used to control mite populations, is no longer be available due to regulatory action. Therefore, it is essential to identify potential alternatives. Garlic (Allium sativum) extracts or chemical components show toxicity to the northern fowl mite, mosquitoes, nematodes, and aphids. Thus, we explored the efficacy of garlic juice in controlling T. putrescentiae. Using a choice test experimental design, approximately 50% of inoculated mites colonized control ham cubes, while no mites remained on cubes dipped in fresh garlic juice. Garlic was ineffective when examined for volatile efficacy, but was toxic in direct contact assays, showing time- and concentration-dependent lethality. Fresh garlic juice at 50–100% strength showed ≥95% mortality in 24 h bioassays, well within the range for acceptable commercial efficacy. However, as fresh garlic juice aged up to 72 h, efficacy was significantly reduced, particularly when diluted with water. Thus, garlic juice acted as a short-term repellent and toxicant in contact models, but application is time sensitive. Nonetheless, it shows potential utility for control of the ham mite.

Effects of Temperature, Relative Humidity, and Protective Netting on Ham Mite Infestation and Fungal Growth on Dry Cured Hams

Effects of Temperature, Relative Humidity, and Protective Netting on Ham Mite Infestation and Fungal Growth on Dry Cured Hams

Use of nets treated with food-grade coatings on dry-cured ham to control Tyrophagus putrescentiae infestations without impacting sensory properties

Dry-cured hams may become infested with the ham mite Tyrophagus putrescentiae during aging. Food-grade coatings have been developed to control mite infestations as a potential alternative to replace methyl bromide, but dipping or spraying these coatings requires additional labor and processing steps. Nets composed of polyester, a polyester/cotton blend and cotton were infused with coatings that consisted of propylene glycol, and either propylene glycol alginate and carrageenan or xanthan gum. Results indicated that the polyester/cotton blend and cotton nets that contained propylene glycol were effective at controlling mite infestations in assays with ham cubes covered in nets. The polyester nets slowed mite growth but were not effective at controlling mite reproduction due to low absorbance of the coatings. Polyester/cotton blend nets treated with coatings on whole hams were not different from control hams with respect to flavor, texture and moistness. Mite infestation tests on whole hams indicated that coated nets with greater stitch densities were effective at controlling mite growth. Future research will include the optimization of coating formulations and scaled-up testing in dry-cured ham plants.

Mite Control and Sensory Evaluations of Dry-Cured Hams with Food-Grade Coatings

The ham mite, Tyrophagus putrescentiae (Schrank; Sarcoptiformes: Acaridae), is the predominant pest of dry-cured pork during aging. This research was conducted 1) to determine the minimal concentrations of propylene glycol necessary for food grade coatings to control mites; and 2) to determine if sensory differences could be detected in hams that were treated with food grade coatings in commercial facilities using difference from control sensory tests. Ham cubes coated with either xanthan gum + 15% propylene glycol or propylene glycol alginate + carrageenan + 7.5% propylene glycol were the lowest propylene glycol concentrations that were effective (P &lt; 0.05) at controlling mite infestations under laboratory conditions. Whole hams from commercial plants that were dipped with coatings were slightly different (P &lt; 0.05) from the non-dipped control hams with respect to flavor, texture and moistness in the first trial. However, hams sprayed with coatings, a lower-cost application than dipping, did not cause sensory differences (P &gt; 0.05) when compared to the control with respect to flavor, texture, moistness, and weight loss in trial 2. This research indicated that dry-cured ham processors could potentially spray these coatings on dry-cured hams during aging to control mite infestations in their plants without negatively impacting the sensory quality of the hams.

Sampling methods to detect and estimate populations of Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae) infesting dry-cured hams

Spatial and temporal dynamics of pest populations are an important aspect of effective pest management. However, absolute sampling of some pest populations such as the ham mite, Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae), a serious pest of dry-cured ham, can be difficult. In this study sampling methods were compared and sampling plans were developed for the ham mite. In one experiment, the number of food-baited traps was maintained at four and the number of mites varied from 500 to 10,000 individuals in environmentally-controlled 18-m2 rooms. The number of mites captured in traps increased linearly as the number of mites released increased. Experiments conducted in simulated ham aging rooms suggested that mites preferred the proximal (closer to the pig's body) to the distal side of the ham. The number of mites captured in traps also varied with trap location relative to hams hung from shelves. There were varying degrees of relationships between the number of mites captured in traps and the sampling methods used, such as counts of mites from the storage rack, vacuum sampling of the floor, and ham sampling. Relationships between absolute counts of mites and the number of mites captured in traps or on specific areas of ham were both moderately strong and significant. Two sampling plans were developed for the mite, and it was determined that an economic threshold close to 1 mite per sample unit on the ham can be estimated with 21 and 40 samples at precision levels of 0.35 and 0.25, respectively, or with 10 ham samples when classifying the mite's infestation level as being above or below an action threshold of 0.43. These sampling plans for the ham mite can facilitate the development and evaluation of cost-effective integrated pest management interventions.

Application of Food-Grade Ingredients to Nets for Dry Cured Hams to Control Mite Infestations

Infestations of Tyrophagus putrescentiae (Schrank; Sarcoptiformes: Acaridae), known as the ham mite, may occur on dry cured hams during the aging process. The fumigant methyl bromide is currently used to control mite infestations, but it will eventually not be available for use since it contributes to the depletion of the ozone layer. The use of ham nets treated with xanthan gum, carrageenan, propylene glycol alginate, and propylene glycol food-grade ingredients on mite orientation to or oviposition on treated or untreated ham cubes, and mite reproduction and population growth over a 10-wk period was evaluated. Behavioral tests indicated that more than 95% of the mites oriented to the ham cubes that were wrapped in untreated nets when compared to treated nets and no eggs were laid on the latter. The reproduction assays demonstrated that there were fewer (P &lt; 0.05) T. putrescentiae produced over a 2-wk period on ham cubes covered with both gum and propylene glycol treated nets, when compared to the untreated or gum-only treated nets over the 10-wk storage period of the experiment. Medium and high concentrations of propylene glycol treatments showed the lowest reproductive rates of mites. No more than 4 mites could be found on each of these treatments in comparison to 200 to 300 mites that were recorded on the untreated hams. This study demonstrated efficacy of using the nets treated with food-grade ingredients during ham aging to control mite infestations on a laboratory scale. Further research will be conducted to determine the effectiveness of the same treated nets on whole hams in commercial aging rooms.

Application of Food Grade Coatings to Prevent Mite Infestion in Dry Cured Ham Processing Facilities

ObjectivesThe ham mite (Tyrophaus putrescentiae Schrank) is the predominant target pest for dry cured ham during aging. Methyl bromide is currently the only effective fumigant for controlling mite infestations in the dry-cured ham industry. However, methyl bromide is being phased out of all industries based on the Montreal Protocol. The objective of this research was to find viable, effective and economical alternatives for the dry cured ham processing facilities.Materials and MethodsFood grade coatings (patent pending) were made from combinations of 1) propylene glycol (PG), xanthan gum (XG), and water or 2) PG, propylene glycol alginates (PGA), carrageenan (CA) and water. Trials were conducted in the summers of 2014 and 2015 in 4 commercial processing facilities and a simulated aging house at Mississippi State University. Whole hams were dipped in coatings or applied to hams with a high pressure spray nozzle and aged for 5 to 8 mo. Difference from control sensory tests (6 to 10 trained panelists, 3 reps per plant) were conducted on ham slices that were removed from the treatment hams to determine the impact of the coatings on sensory quality.To make the coatings more applicable to the dry-cured ham industry, ham nets were infused with the coatings mentioned above and tested for their efficacy at controlling mite infestation. On the laboratory benchtop, 20 mites were inoculated onto single ham cubes (2.5cm × 2.5cm × 2.5cm) that were wrapped with ham nets that were treated with different coatings (n = 5/trt). Total numbers of mites were counted after 14 d of storage at 25°C and 70% relative humidity.Completely randomized design was utilized and Tukey’s test was used to separate the means for data analysis.ResultsControl and treated hams from the commercial trials in both years received sensory scores between 1.6 and 3.2 on the 5 point scale where 1 = no difference and 5 = very large difference. In 3 out of 5 plants, the CA + PGA and low concentration PG treatment hams were not different (p > 0.05) from the blind control treatments. However the high PG treatment was not different (p > 0.05) from the control in 2 out of 5 plants (only in trial 1). In addition, the XG and low concentration PG treatment was only different (P > 0.05) from the blind control in 1 out of 5 plants in both trials. This indicates that the coatings did not impact the flavor in some of the plants but did impact the flavor in the other plants. This may have been due to differences among the plants in non-meat ingredients that were used, aging temperature and humidity, and aging time.For coating infused nets, the mite infestation tests showed that cubes wrapped with nets that were treated with coatings had significantly lower numbers of mites, varying from 3 to 62, after 2 wk, while cubes from the negative control and the positive control with untreated nets had up to 554 mites each. This demonstrates that the treated nets inhibited the reproduction of mites on hams, with some nets performing better than others.ConclusionThe food grade coatings may be applicable for some, but not all, processors. In addition, the coating infused ham nets demonstrate the potential to control mite infestations and should be scaled up for commercial testing.

Efficacy of Controlled Atmosphere Treatments to Manage Arthropod Pests of Dry-Cured Hams.

Research here explored the use of controlled atmospheres (CA) for managing arthropod pests that infest dry-cured hams. Experiments were conducted with low oxygen (O2) achieved with low pressure under a vacuum, high carbon dioxide (CO2), and ozone (O3). Results showed that both low O2 and high CO2 levels required exposures up to 144 h to kill 100% of all stages of red-legged ham beetle, Necrobia rufipes (De Geer) (Coleoptera: Cleridae) and ham mite Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae) at 23 °C. In addition, both low O2 and high CO2 had no significant mortality against the ham beetle and ham mites at short exposures ranging from 12 to 48 h. Ham beetles were more tolerant than ham mites to an atmosphere of 75.1% CO2 and low pressure of 25 mm Hg, which imposed an atmosphere estimated at 0.9% O2. Both low O2 and high CO2 trials indicated that the egg stages of both species were more tolerant than other stages tested, but N. rufipes eggs and pupae were more susceptible than larvae and adults to high concentration ozone treatments. The results indicate that O3 has potential to control ham beetles and ham mites, particularly at ≈166 ppm in just a 24 h exposure period, but O3 is known from other work to have poor penetration ability, thus it may be more difficult to apply effectively than low O2 or high CO2. would be. CA treatment for arthropod pests of dry-cured hams show promise as components of integrated pest management programs after methyl bromide is no longer available for use.