Chilling Regimes Research Articles

Using marsh organs to test seed recruitment in tidal freshwater marshes.

PremiseSeed recruitment niches along estuarine elevation gradients are seldom experimentally field‐tested under tidal regimes of the Pacific Northwest of North America. Addressing this knowledge gap is important to better understand estuary restoration and plant community response to sea level rise.MethodsGermination was tested in marsh organ mesocosms across an elevation gradient (0.5–1.7 m above mean sea level). Seeds were sown on sterile peat moss, and the tops of pipes were secured with horticultural “frost cloth” to ensure no experimental seeds were washed out and no new seeds were introduced. The trials tested artificial and overwinter chilling regimes, as well as the presence and/or absence of a near‐neighbor transplant.Results Carex lyngbyei had significant elevation‐driven germination after overwinter and artificial chilling. Schoenoplectus tabernaemontani had near‐significant germination across elevation after overwinter chilling, and germination in the absence of competition was significantly greater than with a near‐neighbor transplant.Discussion Carex lyngbyei had the highest germination rate at higher elevations, which suggests restricted seed recruitment potential and required clonal expansion to extend into lower marsh elevations. Identifying species‐specific recruitment niches provides insight for restoration opportunities or invasive species monitoring, as well as for estuary migration under sea level rise.

The effect of four alternative chilling regimes on the bacterial load on beef carcasses

The objective of this study was to compare the effect of current (10 °C for 10 h followed by 0 °C with a low fan speed) versus four alternative beef carcass chilling regimes, ranging from -6 °C to 0 °C and wind speeds between 1.5 and 6 m/s on the microbiology of beef carcasses. The temperature and relative humidity (RH) in the chillers, the carcass core and surface temperature, pH, water activity (aw) and carcass weight (drip) loss were recorded. Bacterial concentrations (total viable counts (TVC), total Enterobacteriaceae counts (TEC), Pseudomonas spp., lactic acid bacteria (LAB) and Brochothrix thermosphacta) were also monitored. Similar pH, aw and drip loss (2%) values were obtained regardless of chilling regime. For the most part, bacterial concentrations were also similar and, where statistically significant (P < 0.05) counts occurred, the reductions were low (≤1 log10 cfu/cm2). It was concluded that the current chilling regime was as effective as the tested alternatives in terms of the bacterial quality of the carcasses.

Effect of Carcass Chilling on the Palatability Traits and Safety of Fresh Red Meat.

Chilling procedures have been widely used in livestock abattoirs since the development of refrigeration systems. The major criteria when applying chilling regimes is not only complying with regulations, but economic concerns, and also meat safety and quality assurance requirements. Given recent developments, an updated review is required to guide the industry to choose the best chilling method and to inspire the development of new approaches to chilling. Thus in this paper, the quality and microbial safety of beef, lamb, pork, venison, and bison resulting from different chilling treatments has been reviewed, as well as the underlying mechanism(s) for the different impacts on meat quality traits as a result of different chilling regimes. The effect of fast chilling on the tenderness of beef and lamb is a focus, as some new findings, have recently been reported, while multistep chilling is highlighted as it incorporates the advantages of fast chilling to reduce carcass weight loss, resulting in similar quality improvements as found with slow chilling. It is, suggested, that if spray chilling can be combined with the second phase of multi-step chilling, it will benefit the meat industry in terms of both meat quality and safety. Future studies should focus on combinations of chilling methods with new technologies, such as medium voltage electrical stimulation, muscle stretching, or ultrasound and so on, to move meat quality and safety to a new level.

Market Quality of Late Winter/Early Spring Peony Paeonia after Controlled Dormancy: Dummy Regression Modelling

There is a shortage of herbaceous peony cut flowers in the world market in late winter/early spring. The quality of these prestige flowers, when cultivated in warm climate regions and stored in cooling chambers during dormancy, is influenced by pre-dormancy, dormancy, and post dormancy conditions. In this article, various regimes of peony dormancy with constant and variable temperatures were studied. Containers with plants of cv. ‘Sarah Bernhardt’ were exposed to a pre-dormancy temperature of 15°C and, after two weeks, transferred to cooling chambers in order to keep dormancy under four constant or diurnal temperature regimes. On three different dates, plants from each treatment were transferred to a greenhouse for release from dormancy and the beginning of sprouting. During commercial harvest, data on height and thickness of flower stems, number of harvested flowers per plant, and dates of harvested flowers were collected. Using these data, the index of market quality of peony flowers was defined and regressed on dummy variables that reflected chilling regimes and dormancy duration. Statistically significant differences in market quality were shown between the treatments with the lower storage temperatures 20 C, 2-100 C, and 2-150 C, and the reference treatment with a storage temperature of 2 – 200 C. Statistically significant differences were also shown between the treatments with the shorter storage period of 6 weeks, 4 days or of 8 weeks, on the one hand, and the reference treatment with the storage of 9 weeks, 3 days, on the other. Close results were obtained for the treatments with the constant temperature of 20 C and with the diurnal alternating temperature of 2-100C. Therefore, growers can expect economic gains from saving energy during dormancy under a suitable temperature regime.

Effects of various winter chilling regimes on flowering quality indicatorsof Greek olive cultivars

Aims of the present two-year study were to evaluate the feasibility and identify potential drawbacks of the greenhouse/outdoors parallel plant growth methods for investigation of the effects of various winter chilling regimes on flowering quality indicators of four Greek olive cultivars, namely Mastoidis, Amfissis, and Lefkolia Serron (originating from mountainous and colder areas) compared to cv. Koroneiki (grown mainly in plain warm areas). Groups of potted olive plants were either grown outdoors under ambient temperature or transferred into a greenhouse for one, two, or three months during winter in Crete, Greece. During the first year, chilling accumulation deficit caused a marked decrease in the number of inflorescences per plant in all four olive cultivars. In the second year, chilling accumulation deficit had a negative effect on the number of inflorescences per plant in 'Mastoidis' at 3-month greenhouse treatment but not at all in 'Koroneiki'. Chilling deficit caused an overall decrease in the number of flowers per inflorescence in both 'Koroneiki' and 'Mastoidis' as well as in the percentage of morphologically perfect flowers. The width and length of inflorescences were not affected by chilling deficit in both the cultivars. In vitro pollen germination was reduced in all greenhouse treatments in 'Koroneiki'; however, this effect was significant only after 3 month, whereas no effect was observed in 'Mastoidis'. The results of the present study may contribute to understanding olive flowering biology and selecting appropriate cultivars for new plantations according to historical meteorological data and predicted climate change scenarios.

Meta‐analysis of the effect of chilling on selected attributes of fresh pork

The objective of this study was to examine the effect of accelerated chilling on ultimate pH (pHu), drip loss, color (L*a*b*), and Warner-Bratzler shear force (WBSF) of fresh pork using a meta-analytical approach. Additionally, two subgroups differentiated by stunning method (electrical vs. CO2) were included. The meta-analysis shown that accelerated chilling has an ability to improve quality of fresh pork, however, not all benefits were obviously evident. The overall effects with no overlapping zero CI provide that accelerated chilling can increase ultimate pH and prevent negative alterations in drip loss and color of pork with the evidence of heterogeneity (except pHu). Moreover, CO2 stunning favors fast chilling in development of fresh pork but undesired changes in lightness, redness, and yellowness may occur as well as relatively low shear force increase (probably not detectable by average consumer). Also, fast chilling followed by CO2 stunning has no effect on drip loss. Practical applications The study demonstrated, that accelerated chilling regime has an ability to improve quality of fresh pork, due to increase in ultimate pH and prevention of negative changes in drip loss and color. Additionally, it has been stated, that use of CO2 stunning favors accelerated chilling, however, undesired changes in lightness, redness, yellowness, and shear force may occur. The abovementioned results could provide possibility of chilling processes optimization, which should benefits development of high quality fresh pork in meat industry.

Effect of Delayed Chilling Regimes on the Physicochemical Microbiological and Sensory Properties of Beef from N’dama Cattle

Purpose : This study was carried out to investigate the effect of delayed chilling regimes on quality of beef from N’dama cattle due to non-availability or epileptic supply of electricity, as well as non provision of chilling facilities at the slaughter house at Ayetoro town in Ogun State, Nigeria. Research Method : Three kilogrames of beef (thigh cut) of freshly slaughtered N’dama bull cattle was purchased and subdivided into six parts of 500g, each portion represented a chilling regime or treatment in a randomized experiment as follows: T0 = Immediate (Control), T1 = Chilling after 2hours delay, T2 = chilling after 4hours delay, T3 = chilling after 6hours delay, T4 = chilling after 8hours delay, T5 = chilling after 10hours delay and were chilled at 40C for 24 hours in a refrigerator and were removed for physical, chemical, microbiological and sensory quality analysis at p Findings : The result showed that there were significant differences in the physical, chemical, microbiological as well as sensory characteristics of the meat irrespective of the chilling regime. Meat colour, water holding capacity, cooking yield, fat, ash, flavor, tenderness, juiciness, texture and over all acceptability of the meat decreased (p Research Limitation : This study was limited to the use of beef from N’dama bull cattle at Ayetoro, the headquarters of Yewa North Local Government Area in Ogun State, Nigeria. This was due to the fact that N’dama bull cattle are very common and often slaughter at this point. Originality/value : It was recommended based on the results from this study that beef from N’dama bull cattle should be chilled for 4 hours after slaughter otherwise its quality will deplete which might render the meat to be unacceptable to the consumers.

Meat inspection and hygiene in a Meat Factory Cell – An alternative concept

The Meat Factory Cell (MFC) concept differs from conventional abattoirs by partly working in cell stations instead of production lines. It combines and merges elements of today's separate processes and disciplines, namely “slaughter” and “meat primal cutting”, and “disassembles” the carcass from outside-in where limbs, neck, back and loin are removed before internal organs. The aim of this work is to qualitatively assess future meat inspection and hygiene of pork carcasses in the MFC. A holistic assessment of the carcass parts is needed to interpret the significance of findings on separate parts. The MFC offers some opportunities for targeted inspection with cutting edge diagnostic technology. Improved hygiene is expected from the MFC concept due to the fact that limbs, neck and loin are removed first and are not subject to faecal contamination from intestinal content. The MFC provides opportunities for customized chilling regime for different parts, targeted decontamination or pathogen killing processing, which should contribute to safer meat products and less energy consumption. We expect that the MFC approach will potentially fulfill the principles of Codex alimentarius and will improve public health compared to conventional slaughter and meat inspection.

Effect of Gradual and Shock Chilling Stress on Abscisic Acid, Soluble Sugars and Antioxidant Enzymes Changes in ‘Sultana’ Grapevine.

Plants may show different behaviours during exposure to low temperature stress through various mechanisms. In this study, the chilling responses of ‘Sultana’ grapevine were investigated during a gradual chilling (2 °C/h) and also during a shock chilling (5 °C/h) from 24 °C to 4 °C. After artificial chilling stress, electrolyte leakage, lipid peroxidation, hydrogen peroxide production and antioxidant enzymes activities were measured in all plants leaves. Moreover, the potential of plant to accumulate abscisic acid and osmoregulants were compared under both gradual and shock chilling stresses. Based on the results, a significant difference was found between the electrolyte leakage, lipid peroxidation and hydrogen peroxide content of plants under two chilling regimes. These indices were found to be higher in shock chilling stressed plants compared with gradual chilling stressed vines because of the lower catalase, peroxidase and ascorbate peroxidase activities. Moreover, gradual chilling stressed vines exhibited higher accumulation of abscisic acid, proline and total phenolic compounds. The chlorophyll degradation and relative water content were lower in gradual cold stressed plants. Glucose and fructose, unlike sucrose showed higher concentration in gradual cold stressed vines. Totally, under gradual chilling stress grapevine plants showed better cold acclimation by lower oxidative stress and higher accumulation of osmoregulants in compared with shock chilling stressed vines.

The fate of Salmonella Typhimurium and Escherichia coli O157 on hot boned versus conventionally chilled beef

This study investigated the fate of Salmonella Typhimurium and Escherichia coli O157 on hot boned versus conventionally chilled beef. Beef samples were individually inoculated with S. Typhimurium ATCC 14028, S. Typhimurium 844, E. coli O157 EDL 933 or E. coli T13. Half the samples were subject to the same time-temperature chilling profile used for conventionally chilling beef carcasses while the other half was subject to hot boned conditions. The surface pH (5.5) and aw (0.95 to 0.97) were stable. S. Typhimurium and E. coli O157 counts, which decreased by up to 1.0 and 1.5log10cfucm−2, respectively, were statistically similar (P>0.05), regardless of the chilling regime applied, with the exception of E. coli O157 EDL 933, where the counts on hot boned beef were significantly (P<0.05) higher. It was concluded that any decrease in pathogenic bacteria during beef chilling may be significantly (P<0.05) less for hot boned beef depending on the bacterial strain.Hot boning may therefore result in an increased risk to the consumer.

Effects of pork differentiation strategies in Canada on pig performance and carcass characteristics

Performance and quality traits were measured in carcasses from combinations of genotype, diet supplement, slaughter weight, and carcass chilling regime. Iberian-crossed pigs had lower live animal performance than Duroc and Lacombe. From 70 to 115 kg, Lacombe pigs grew slightly faster than Duroc. Duroc carcasses had a higher lean percentage, heavier ham and picnic primals, and lighter loins and bellies, compared with Lacombe and Iberian. Heavier carcasses had lower lean yield, except those from Iberian-crossed pigs, and bigger bellies. Meat from Duroc-crossed pigs was lighter in colour and higher in marbling, with intermediate values for fat hardness. Iberian carcasses displayed dark meat with intermediate marbling and the hardest fat. Meat from Lacombe pigs was the leanest although, like in all three breeds, marbling scores were higher in heavier carcasses. Generally, supplementing with canola and flax decreased and blast chilling increased fat hardness values. Dietary canola also seemed to affect meat colour traits, but these effects were not consistent among breeds and slaughter weights. The commercial combination of Duroc breed, control diet, and 115-kg slaughter weight showed a balance in terms of performance, carcass, and quality traits. Other combinations evaluated in this study showed potential to efficiently produce differentiated pork.

Effects of Dry Chilling on the Microflora on Beef Carcasses at a Canadian Beef Packing Plant

The aim of this study was to determine the course of effects on the microflora on beef carcasses of a commercial dry chilling process in which carcasses were dry chilled for 3 days. Groups of 25 carcasses selected at random were sampled when the chilling process commenced and after the carcasses were chilled for 1, 2, 4, 6, 8, 24, and 67 h for determination of the numbers of aerobes, coliforms, and Escherichia coli. The temperatures of the surfaces and the thickest part of the hip (deep leg) of carcasses, as well as the ambient air conditions, including air temperature, velocity, and relative humidity (RH), were monitored throughout the chilling process. The chiller was operated at 0°C with an off-coil RH of 88%. The air velocity was 1.65 m/s when the chiller was loaded. The initial RH levels of the air in the vicinity of carcasses varied with the locations of carcasses in the chiller and decreased rapidly during the first hour of chilling. The average times for shoulder surfaces, rump surfaces, and the deep leg of carcasses to reach 7°C were 13.6 ± 3.1, 16.0 ± 2.4 and 32.4 ± 3.2 h, respectively. The numbers of aerobes, coliforms, and E. coli on carcasses before chilling were 5.33 ± 0.42, 1.95 ± 0.77, 1.42 ± 0.78 log CFU/4,000 cm(2), respectively. The number of aerobes on carcasses was reduced by 1 log unit each in the first hour of chilling and in the subsequent 23 h of chilling. There was no significant difference (P > 0.05) between the numbers of aerobes recovered from carcasses after 24 and 67 h of chilling. The total numbers (log CFU/100,000 cm(2)) on carcasses before chilling and after the first hour of chilling were 3.86 and 2.24 for coliforms and 3.30 and 2.04 for E. coli. The subsequent 23 h of chilling reduced the numbers of both groups of organisms by a further log unit. No coliforms or E. coli were recovered after 67 h of chilling. The findings show that the chilling regime investigated in this study resulted in significant reductions of all three groups of indicator organisms.

Effects of Early Post-Mortem Rate of pH fall and aging on Tenderness and Water Holding Capacity of Meat from Cull Dairy Holstein-Friesian Cows

Fast or slow muscle pH fall may give unacceptable purge losses or tough meat, depending much on concomitant evolution of muscle temperature early post-mortem, costing millions of euros to the meat industry. Tenderness and purge losses of &lt;em&gt;Longissimus thoracis/lumborum&lt;/em&gt; (&lt;em&gt;LTL&lt;/em&gt;) and &lt;em&gt;Gluteus medius&lt;/em&gt; (&lt;em&gt;Gm&lt;/em&gt;) sampled from cull dairy cows differing in production status (10 lactating vs. 22 dried off) and aging time, were evaluated regarding different rates of pH&lt;sub&gt;2&lt;/sub&gt; fall. Shear force related to pH&lt;sub&gt;2&lt;/sub&gt; was dependent on muscle and aging time. The intermediate glycolysis led to lower shear force in &lt;em&gt;LTL&lt;/em&gt;, while the faster produced best quality in &lt;em&gt;Gm&lt;/em&gt;. Purge was influenced by pH&lt;sub&gt;2&lt;/sub&gt; (P=0.0077), aging (P&amp;lt;0.0001) and muscle*pH&lt;sub&gt;2&lt;/sub&gt; interaction (P&amp;lt;0.0001). Aging affected thawing (P&amp;lt;0.0001), grilling (P=0.0004) and overall losses (P&amp;lt;0.0001). Under the ruled chilling regime, the fast pH fall in &lt;em&gt;Gm&lt;/em&gt; and the slow pH fall in &lt;em&gt;LTL&lt;/em&gt; approached out of the ideal pH6/temperature limits, being compatible with heat and cold shortening, respectively.

Altered post-mortem metabolism identified in very fast chilled lamb M. longissimus thoracis et lumborum using metabolomic analysis

The aim of this experiment was to use metabolomic techniques to investigate the energy metabolism in lamb M. longissimus thoracis et lumborum subjected to very fast chilling (VFC) post-mortem. The tissue was prepared by 2 different operators and subjected to very fast chilling (less than 0°C within 1.5h of slaughter) or typical chilling regimes (Control; 0°C within 22h of slaughter). Non-targeted metabolomic analysis (1H NMR) and targeted analysis (31P NMR, HPLC-PDA and HPLC–MS/MS) were used to examine the change in muscle metabolites post-mortem. One VFC treatment, which resulted in a colder core temperature and more tender meat, had higher levels of glycolytic intermediate metabolites pre-rigor as well as more of the end-products of adenosine and nicotine nucleotide metabolism pre-rigor, relative to conventionally chilled treatments. In conclusion, VFC to less than 0°C within 1.5h of slaughter causes considerable changes in metabolism and rigor onset, which are associated with tender meat.

Combined effect of chilling and desiccation on survival of Escherichia coli suggests a transient loss of culturability

Dry air carcass chilling regimes used in some Australian meat works, which not only rapidly reduce the temperature of the carcasses but also dry the meat surface initially, are reported to cause reductions in the number of Escherichia coli present on carcasses after processing. This study used a laboratory broth model system to systematically investigate the basis of such reductions by simulating chilling and desiccation profiles observed on carcasses separately and, finally, in combination. Observed growth was compared to the predictions generated by a strain-specific modification of a validated E. coli growth model (Mellefont et al., 2003; Performance evaluation of a model describing the effects of temperature, water activity, pH and lactic acid concentration on the growth of E. coli). Good agreement between observed and predicted growth was evident when chilling or desiccation profiles were simulated individually. However, when chilling and desiccation profiles were applied simultaneously the observed population kinetics deviated from those predicted by the model. An initial reduction in cell numbers, not predicted by the model, was observed followed by an anomalously rapid increase in population density before growth resumed at a rate expected for the conditions imposed. From our analysis of the kinetics of the population changes, we suggest that the initial decrease in cell numbers was unlikely due to cell death, because conditions were growth permissive. Considering all possible explanations from the observed population kinetics, we propose that a temporary loss of the ability to produce colonies on agar plates may occur. These results may explain reports of increases in E. coli numbers two to three days after commencement of chilling, compared to those observed after 16–24h, despite the imposition of growth-preventing temperatures.

Scientific Opinion on the public health risks related to the maintenance of the cold chain during storage and transport of meat. Part 1 (meat of domestic ungulates)

Salmonella spp., verocytotoxigenic Escherichia coli (VTEC), Listeria monocytogenes and Yersinia enterocolitica are the most relevant microbial pathogens when assessing the effects of beef, pork and lamb carcass chilling regimes on the potential risk to public health. Moreover, as most bacterial contamination occurs on the surface of the carcass, only the surface temperature is an appropriate indicator of bacterial growth. The growth of these four pathogens (using E. coli models for VTEC) during different time-temperature chilling scenarios was estimated using commercial slaughterhouse data and published predictive microbiology models. The outputs suggest it is possible to apply slaughterhouse carcass target temperatures higher than the currently mandated 7 °C throughout the carcass (including the core) in combination with different transport durations without obtaining additional bacterial growth. Combinations of maximum surface temperatures at carcass loading and maximum chilling and transport times, that result in pathogen growth equivalent or less than that obtained when carcasses are chilled to a core temperature of 7 °C in the slaughterhouse are provided.

Effect of ageing time on suckling lamb meat quality resulting from different carcass chilling regimes

The effect of ageing on suckling lamb carcasses subjected to three chilling treatments was studied: Conventional (2°C for 24h), ultra-fast (−20°C for 3.5h then 2°C until 24h post mortem) and slow chilling (12°C for 7h then 2°C until 24h post mortem) treatments. Meat quality measurements were carried out in carcasses at 24h post mortem and also after 5days of ageing. Carcass chilling losses were not affected by a chilling regime. Aged meat showed higher cooking losses than non-aged meat (p<0.05). Sarcomere length of ultra-fast t was shorter (p<0.05) than conventional and conventional was shorter than slow chilling treatment (p<0.05), at 24h and after 5days of ageing. Conventional and ultra-fast chilling treatments resulted in higher shear force values at 24h post mortem (p<0.05) compared to slow treatment. All treatments improved sensory scores with ageing (p<0.05), but ultra-fast chilling treatment did not attain higher values as the other two treatments.

Pupal diapause development and termination is driven by low temperature chilling in Bactrocera minax

Bactrocera minax is a major citrus pest in China, Bhutan, and India. It is univoltine and exhibits pupal diapause during winter. To better understand pupal diapause in this pest, we investigated pupal survival and pupal developmental duration under field and laboratory conditions. Specifically, we tested if pupal chilling was required for diapause development and termination. Nearly all mature larvae collected at the end of the citrus season entered pupal diapause. For pupae exposed in the field, natural chilling for less than 3 months resulted in more than 70 % mortality. However, exposure to winter conditions for 3 months or more both decreased pupal mortality and developmental duration when pupae were returned to the laboratory and held under constant temperature (25 C). When pupae were gathered from the field in November and exposed to different chilling regimes in the laboratory, the chilling duration (30 vs 60 days) had significantly more impact on pupal survival than the specific chilling tem- perature (6, 8, 10, or 12 C constant). However, both chilling duration and chilling temperature impacted on the pupal developmental duration, with longer chilling dura- tion and higher temperatures decreasing pupal develop- mental duration. In conclusion, we demonstrated that pupal diapause development and termination in B. minax is strongly influenced by chilling conditions. Increasing cold exposure led to significantly and consistently faster adult eclosion and improved synchronization of adult emer- gence. This knowledge will help with the laboratory rear- ing of B. minax, an essential step in the long-term management of this pest.

Effect of very fast chilling and aging time on ultra-structure and meat quality characteristics of Chinese Yellow cattle M. Longissimus lumborum

Objectives of the current study were to evaluate meat ultra-structure and tenderness variation at different chilling regimes and aging times. Hot boned longissimus lumborum of 18 Chinese crossbred cattle were divided into 4 portions per side. One portion underwent very fast chilling (VFC, at −21°C to achieve core temperature of 0°C, then transferred to another incubator at 2°C), whereas other treatments were held at 14, 7 and 0°C for 10h postmortem, respectively. At 10h postmortem, all muscles were vacuum aged at 2°C for 21d. Cold shortened muscles had greatest absolute amount of tenderization during aging. VFC caused lowest sarcomere length, with super-contractions, ruptured Z-lines and myofibril cleavage, but improved myofibril fragmentation index (MFI), with no significant negative effect on toughness. Overall, aging improved the meat quality of cold shortened beef. Moreover, it should be prudent in some applications to apply VFC to excised muscles from a food safety perspective, and to improve tenderness compared to cold-shortened muscles.

Microscopic Fungi on Fresh Meat Derived from Roe Deer (Capreolus Capreolus) and Red Deer (Cervus Elaphus)

Biežāk sastopamās mikroskopiskās sēnes stirnu(Capreolus capreolus)un staltbriežu(Cervus elaphus)gaļā