Assessment of the hygienic adequacy of a commercial hot boning process for beef by a temperature function integration technique.

The hygienic performance of a commercial hot boning process for beef carcasses was assessed by a temperature function integration technique. The potential proliferation of Escherichia coli was calculated from 50 temperature histories for the persistently warmest, microbially contaminated regions of product passing through both the carcass cutting and carton cooling phases of the process. The maximum calculated proliferation was similar to, but the average proliferation was more than, the respective values previously obtained for a beef side cooling process that complied with Good Manufacturing Practice. After upgrading of the carton cooling facility the process was re-assessed. Then, for a sample of 50 temperature histories, the maximum proliferation was less than, and the average proliferation was similar to, the respective values for the side cooling process. Observed proliferations of E. coli inocula in cooling cartons of product were compared with the proliferations calculated from temperature histories obtained from sites close to inocula. The pairs of calculated and observed values mostly agree within +/- 1 generation.     

Evaluation of a pilot on-line instrument for the measurement of lean content of cartoned boneless beef

A laboratory evaluation of a pilot, new instrument for the on-line (batch continuous) measurement of the per cent chemical lean content (CL) of whole cartons (nominally 27.2 kg) of boneless beef, based on an idealized design, is reported. For 24 cartons obtained from an export meatworks there was a highly linear (P < 0.001) dependence of CL on (reciprocal of) the instrument reading. The standard deviation of the predicted CL about this regression line was 2.02. For a further 20 cartons in which the cardboard was equilibrated at high RH prior to packing with the meat, the standard deviation in CL was 3.14. Predictions for CL were not significantly influenced by the order in which the meat pieces were packed into the carton, but were significantly (P< 0.001) affected by the size of the meat pieces. Best results of predicted CL were obtained with large meat pieces in cartons as supplied from the meatworks. These findings together with the fact that model predictions were not improved by a temperature term for meat (range 8.7–15.7°C) should augur well for future development of the instrument.     

Temperatures and ages of boxed beef packed and distributed in Canada

Boxes of beef were examined when product was packed and when boxes were loaded out of five packing plants, when boxes were loaded into and loaded out of seven refrigerated warehouses, and when boxes were received and opened at 21 retail stores. At each stage of handling at each facility, the boxes to be examined were selected at random. For each selected box, the temperature of product at the centre of the box was measured, and the date of packing and the plant of origin were noted. When cuts were packed, the minimum, median and maximum temperatures were about 2, 6 and 18 °C, respectively. Temperatures were successively lower when boxes were loaded out of packing plants, into warehouses and out of warehouses. When loaded out of warehouses, the minimum, median and maximum temperatures were about −2, 1 and 8 °C, respectively. The ranges of temperatures were similar, but the median temperatures were about 2 or 1.5 °C, respectively, when boxes were received at or were opened at retail stores. At packing plants and warehouses, the temperatures of manufacturing and ground beef were lower than those of cuts, but at the retail store the temperatures of all types of product were similar. When boxes were opened at retail stores, the minimum, median and maximum ages of cuts were about 2, 20 and 130 days, respectively; and the corresponding ages for manufacturing and ground beef were 2, 7 and 56 days, respectively. The data indicate that boxed beef is generally cooled to and maintained at temperatures within the range sought by the meat industry. However, cooling to chiller temperatures of product that is packed while warm can take several days; and some product is held for times that are excessive in view of the temperatures of boxed beef.     

Measurement of Convective Heat Transfer Coefficients During Food Freezing Processes

Any prediction of freezing time for a food product depends on accurate heat transfer coefficients. The purpose of this investigation was to examine experimental procedures for accurate determination of convective transfer coefficients during freezing of food products. Measurements of heat transfer coefficients during cooling of any acrylic transducer and ground beef with similar size and shape were conducted at air temperatures below initial freezing point of the product. The results indicate that accurate measurements of the coefficients can be achieved through nonlinear regression analysis of temperature histories within an acrylic transducer.     

Multiparameter Analysis of Cooling Efficiency of Ventilated Fruit Cartons using CFD: Impact of Vent Hole Design and Internal Packaging

Forced-air cooling (FAC) efficiency of fruit packed in ventilated cartons can be considerably improved by revising vent hole design and tailoring these openings according to the internal packaging used. Current vent hole designs for fruit cartons, however, often result from trials and errors or are developed in order to improve a specific package functionality, such as fruit cooling rate. This study presents a novel multiparameter evaluation process for ventilated fruit packaging. This multi-parameter strategy evaluates cooling rate and cooling uniformity, airflow resistance and energy efficiency. Computational fluid dynamics is used to evaluate the impact of internal trays and four vent hole designs. One of the designs investigated is currently used in commercial export of apples, while the other three are new configurations proposed to improve fruit cooling efficiency. Results showed that the addition of trays to the existing commercially used Standard Vent hole design increased ventilation energy consumption by 31 % compared to cartons without trays, but in the two newly proposed carton designs (Altvent and Multivent), the energy usage was reduced by 27 and 26 %, respectively, as airflow was distributed more evenly between the five fruit layers. The use of the new vent hole designs (Altvent and Multivent) compared to the Standard Vent design, also considerably improved cooling uniformity and energy efficiency during FAC, reducing cooling heterogeneity by 79 and 51 %, as well as energy consumption by 48 and 7 %, when packed with and without trays, respectively. By simultaneous evaluation of multiple parameters, this analysis approach thus unveiled the benefits and disadvantages of the new ventilated carton designs and can be used to further improve vent hole designs for specific cold chains.     

典型电商运输包装对猕猴桃运输微环境及贮藏品质的影响

为了探索3 种典型电商运输包装猕猴桃所处运输微环境变化特点及其对后续贮藏品质的影响,分别采用单纯纸箱、纸箱内衬聚苯乙烯泡沫箱和纸箱内衬聚乙烯发泡棉材料（果实单格放置）3 种形式包装对预冷猕猴桃进行运输,记录运输期间包装箱内的温湿度和振动强度变化,运输结束后分装入打孔塑料盒,贮藏于（4.0±0.5）℃的环境中并定期测定其品质变化。结果表明,纸箱内衬聚苯乙烯泡沫箱和内衬聚乙烯发泡棉材料均能够有效延缓包装箱内温度的上升,保持包装内的湿度;猕猴桃运输过程中振动主要来自于车辆的加减速和颠簸,纸箱内衬聚乙烯发泡棉材料的综合减振效果最好。运输过程的颠簸及温度变化是影响猕猴桃品质的主要因素,经过纸箱内衬聚乙烯发泡棉材料包装运输的猕猴桃在贮藏期间质量损失率上升最缓慢,硬度最高,颜色最鲜艳,总可溶性固形物、总酸质量分数较高,综合贮藏品质最好;纸箱内衬聚苯乙烯泡沫箱包装运输的猕猴桃贮藏品质稍次之,单纯纸箱包装运输的猕猴桃贮藏品质最差。综合运输微环境及货架期品质变化,纸箱内衬聚苯乙烯泡沫箱和纸箱内衬聚乙烯发泡棉材料均是适于电商运输猕猴桃的包装方式。     

Interaction Between Polyethylene Laminated Cartons and Aseptically Packed Citrus Juices

The quality of citrus juices aseptically packed into laminated cartons and glass jars was evaluated at three temperatures. Model solutions were used to elucidate effect of contact surface on components in the product. The extent of browning and loss of ascorbic acid was found to be greater in cartons than in glass. The d-limonene content of the juices in cartons was reduced by about 25% within 14 days of storage due to absorption by the polyethylene. Sensory evaluation showed a significant difference after 10 – 12 wk between juices packed in glass and cartons stored at ambient temperatures.     

Flavour and vitamin stability in pasteurized milk in polyethylene-coated cartons and in polyethylene bottles

Commercially pasteurized, non-homogenized full cream milk in 2-pt white polyethylene (PE)-coated cartons overprinted with blue, and in 4-pt PE bottles was stored for 4 d in the dark or under white fluorescent light of 4000 1x, at a temperature of 7°C. The flavour of milks kept in the dark remained good, but exposure to light resulted in early off-flavour development: cartoned milk was disliked by a flavour panel after about 17.5 h exposure and milk in the PE bottles after 9 h. Vitamins A and B₂ were stable in the milk during 4 d storage in the dark in both bottles and cartons, and in cartons exposed to light. In the bottled milks, light-induced losses of these vitamins after 4 d were, respectively, 15% and 35%. but there was little or no loss before the development of light-induced flavour. Loss of total vitamin C by day 4 was about 50% in the dark, irrespective of container. In the cartons exposed to light, 66% of the vitamin C was lost, while virtually none remained in the exposed, bottled milk. There was also a markedly greater loss of vitamin C in the bottled milk than in the cartoned milk at the time the flavour became unacceptable. The dissolved O₂ concentration dropped considerably in the bottled milk exposed to light, but only marginally in the cartons. There were small increases in dissolved O₂ in the dark in both types of container.     

Microbiological, physicochemical and sensory quality of maple syrup aseptically packaged in paper-based laminate

Quality of maple syrup packaged in paper-based laminate at 82°C or room temperature (25°C) was evaluated and compared to a reference syrup packaged in glass bottles stored at 4°C. to prevent microbial growth and blown containers, maple syrup must be heated at 82°C before packaging. Significant pH decrease related to storage temperature was similar to the observation of other authors for glass bottles and cans. Syrup in laminate cartons stored at 4°C, had higher transmittance measurements with time, but at higher storage temperatures, browning effect related to caramelization of sugars balances this transmittance increase. Changes in invert sugar level were significant only in syrup packaged in laminate at 25°C and stored at 23°C and 37°C and were related to the microbial growth. Physicochemical changes were not large enough to affect the overall quality of the product. 'Burnt sugar' off-flavour was detected for samples stored at 37°C. Packaging maple syrup in paper-based laminate at 82°C is an economic alternative to glass bottles, while maintaining a good quality product.     

TRANSIENT COOLING OF CONDUCTION HEATING PRODUCTS DURING STERILIZATION: TEMPERATURE HISTORIES

Temperature histories at the geometric center of containers filled with conduction heating products exhibit a rise after steamoff under certain conditions. This temperature rise (called overshooting), is quantified for cylindrical containers subjected to air and water cooling. Results of computer simulations using the Finite Element method suggest that the extent of overshooting is greater during air cooling than during water cooling. Heat penetration tests in laboratory and industrial retorts indicate that the overshooting phenomenon during water cooling is especially pronounced when conduction heating products are packaged in large metal containers and glass jars (e.g., a temperature rise of 2.5°C for 30 min was measured in a No. 10 can).     

COLOR AND VITAMIN C CONTENT IN MANDARIN ORANGE JUICE AS AFFECTED BY PACKAGING MATERIAL AND STORAGE TEMPERATURE

Mandarin orange (Citrus reticulata) juice was packed in two different non-transparent cartons made of polyethylene, cardboard and (1) aluminum foil (Tetrapak ^® ) or (2) ethylene vinyl alcohol copolymers (Pure-pak ^® ) and was stored at 4C or room temperature (25  ±  3C). During the shelf life of these juices (35 days), changes in the headspace gas composition, vitamin C and CIEL*a*b* color coordinates were evaluated. In addition, a consumer panel evaluated the sensory color of the juices. Mandarin orange juices darkened and ascorbic acid content decreased with storage time. Type of carton and storage temperature played a predominant role in determining the final juice quality, with Tetrapak ^® carton providing the juice with the best quality (intense orange color and high vitamin C content and consumer preference) throughout their shelf life.

PRACTICAL APPLICATIONS

This study was a clear example of how research can help real food companies in selecting the right materials for their production lines. In this particular case, the results presented show how Tetrapak^® packaging led to a final mandarin orange juice of higher quality compared to Pure-pak^® packaging. Therefore, citrus processing companies have some scientific data comparing the behavior of these two types of non-transparent cartons. Besides, the companies manufacturing these cartons also have some information about their materials and can use it to improve them.     

Inactivation of Bacillus subtilis spores on aluminum and polyethylene preformed cartons by UV-excimer laser irradiation

The efficacy of UV KrF-excimer laser light (at 248 nm) to inactivate Bacillus subtilis spores loaded onto preformed cartons was found to be dependent on the interior carton coating and scheme by which the irradiation was applied. When the carton was held static during UV laser treatment, the majority of the dose was delivered to the base of the carton and to a lesser extent to the upper part of the pack. In this arrangement no irradiation of the interior sides of the carton was observed. A more even distribution of dose was achieved, however, by moving the carton within the laser beam during irradiation treatment. The distribution of UV was also found to be dependent on the type of carton interior coating. With aluminum cartons the dose measured was found to be significantly greater (P < 0.01) and more evenly distributed across the interior compared to when polyethylene packs were tested. Under optimized conditions no spore survivors were detected on aluminum cartons preloaded with 9.5 x l0 B. subtilis spores by applying a UV laser output dose of 160 J. In comparison, the same conditions only achieved a significantly lower (P < 0.01) reduction in spore numbers (log count reduction 4.2) when polyethylene cartons were used. This difference in lethality and UV distribution of laser light was associated with the higher internal reflection of photons with aluminum cartons. The suitability of UV-excimer lasers for sterilizing preformed cartons over traditional germicidal lamp-based methods is discussed.     

Establishment of provisional quality assurance guidelines for assessing the hygienic adequacy of beef side cooling regimes

The hygienic adequacy of beef side cooling regimes can be assessed from temperature histories obtained for a site within the aitch-bone pocket. Each temperature history is used to generate a numerical value, the Process Hygiene Index (PHI), which reflects the amount of mesophilic pathogen growth that the cooling regime allows. The PHI concept is proposed as a quality assurance tool for assessing beef side cooling. To develop provisional PHI guidelines for acceptable cooling, a chilling regime for carcasses which would yield frozen, boxed products was monitored on each of 11 days. Although the regime was hygienically acceptable, it was marginal in that cooling some sides to 7 °C took almost the permitted maximum time of 48 hr. The guidelines, derived from that process, based on a conventional three-class sampling plan, where the maximum acceptable value (M) is the highest PHI value obtained and the target value (m) is the 80th percentile PHI value of the pooled data from all acceptable, monitored trials. The proportion (c) of sample values that may lie between (m) and (M) was determined from the batch that had the highest PHI values. The proposed guidelines for the hygienically acceptable cooling of beef sides destined for fabrication to frozen product are: M = 19; m = 14; and c = 60 %, with no fewer than five samples being tested per batch (n ≥ 5). For sides destined for chilled products, a processor may wish to use more stringent, in-house guidelines, to assure an extended product storage life.     

双通道超高速条烟提升机的设计与应用

当条烟输送系统中的单道S型提升机的输送能力>50条/min时,容易导致链板磨损加快、条烟折角、表面BOPP薄膜划痕、条烟破损率高等问题,无法满足超高速包装机组的生产输送需求,为此对条烟提升机进行了改进。在单道S型提升机条烟平条进烟、平条出烟方式的基础上,设计了双通道超高速条烟提升机,实现了条烟与输送链板运动方向的一致,减少了条烟在滚轮和链板上表面的滑动摩擦。应用效果表明,条烟输送稳定可靠,提升机最大输送能力由50条/min提高到100条/min,链板使用寿命由2～3年提高到5～6年,条烟折角、表面BOPP薄膜划痕、破损等缺陷由5%～7%降低到0.5%以下,提高了条烟输送能力和产品质量。     

A MODEL FOR PREDICTING THE GROWTH OF LISTERIA MONOCYTOGENES IN PACKAGED WHOLE MILK

Experiments were conducted to determine growth characteristics of Listeria monocytogenes in sterilized whole milk at nine temperatures in the range of 277.15 to 308.15K (4 to 35C). Based on these data, the parameter values of the Baranyi dynamic growth model were statistically determined. Finite element software, ANSYS, was used to determine temperature distributions in milk cartons subject to a time‐varying ambient temperature profile. The space‐time‐temperature data were input to the Baranyi dynamic growth model, to predict the microbial population density distribution and the average population density in the milk carton. The Baranyi dynamic growth model and the finite element model were integrated and validated using experimental results from inoculated sterilized whole milk in half‐gallon laminated paper cartons. In all experiments, the milk cartons were subjected to the same temperature profile as the Baranyi dynamic growth model. Experimental microbial counts were within predicted upper and lower bounds obtained using the integrated Baranyi dynamic growth and finite element models. In addition, the growth curve at the mean value of initial physiological state parameter for L. monocytogenes underpredicted the microbial growth (standard error = 0.54 log (cfu/mL) and maximum relative difference = 15.49%).     

Flavor and Aroma Influences on Acceptance of Polyvinyl Chloride Versus Vacuum Packaged Ground Beef

Untrained panelists compared vacuum packaged (VP) ground beef to polyvinyl packaged (PVC) product to determine if cooked flavor differences existed and to determine cooked flavor and raw aroma preferences. Beef trim was ground and packaged 12 days (VP) and 3 days (PVC) prior to testing. Triangle testing indicated that the pan fried samples had different (P<0.01) beef flavor. Preference testing indicated that the PVC product was preferred over the VP product. Both products were liked. Seventy percent would cook the VP product based on its raw aroma, 49% would cook the PVC product. Based on flavor and aroma characteristics, the VP product should compete favorably with PVC packaged ground beef.     

Investigation of the levels of N(τ)-Methylhistidine in a range of beef cuts and offals

Protein-bound N(τ)-methylhistidine (N-MeHis) has been suggested as an index for the estimation of muscle (meat) protein in meat and meat products. This paper examines the levels of N-MeHis in a range of six prime beef cuts together with beef flank, cheek, mechanically recovered meat (MRM) and offals. The study was undertaken by two separate laboratories using a previously reported HPLC procedure involving the conversion of N-MeHis to a fluorescent derivative. It is shown that, whilst similar N-MeHis levels are present in the prime cuts, there is considerable variation in those found in the other cuts and offals. The average N-MeHis level in six prime cuts observed at both laboratories is 122 μg/g fat-free connective tissue-free (FFCF) meat; however, flank exhibits apparently high N-MeHis levels, whilst cheek and MRM contain only approximately 70% of the level found in the prime cuts. The offals contain between 0 and 65% of the N-MeHis level found in prime cuts. The greater variability and the often lower value of the N-MeHis content of these legitimate meat materials preclude the establishment of a single realistic index for FFCF beef, and present fundamental problems for the assessment of the lean meat content of manufactured beef products by N-MeHis determination.     

EFFECT OF PACKAGING MATERIALS ON COLOR,VITAMIN C AND SENSORY QUALITY OF REFRIGERATED MANDARIN JUICE

ABSTRACT

Refrigerated mandarin juice was packed in four different containers, three cartons with different composition and one polyethylene terephthalate transparent bottle, and was stored at 4C for 90 days. During the storage of these juices, changes in the headspace gas composition, vitamin C, and CIE L*, a* and b* color coordinates were evaluated. In addition, a consumer panel evaluated the sensory color, fresh mandarin flavor and presence of off‐flavors in the juices. Experimental data indicated that the deterioration of mandarin juices (ascorbic acid degradation and darkening of color) was triggered by the rise in oxygen in the headspace of the storage containers. The type of container played a predominant role in determining the juice quality, with carton containers with an inner layer of aluminum foil providing the juices with the best quality throughout their storage.

PRACTICAL APPLICATIONS

Results from this study will provide manufacturers of mandarin juice with information dealing with the storage and quality of juices packed in different containers. In this way, if manufacturers want to use transparent polyethylene terephthalate (PET) bottles showing the color and appearance of the juice, they will be aware that the shelf life of the juice will be much shorter than in packed cartons; this reduction will be from more than 90 to 36 days (PET bottle). On the other hand, if manufacturers want to use carton for their packaging, they will be aware that using a container with a thick inner layer of aluminum foil will maintain the quality of the juice for a longer time (over 90 days) compared with a shelf life of about 54 days from cartons with an inner layer of ethylene vinyl alcohol copolymers.     

Estimation of human dose of staphylococcal enterotoxin A from a large outbreak of staphylococcal food poisoning involving chocolate milk

An outbreak of gastroenteritis in a school district in the United States was determined to be staphylococcal food poisoning due to 2% chocolate milk containing staphylococcal enterotoxin A (SEA). Twelve one-half pint (approx 0.28 l) cartons of the 2% chocolate milk from this outbreak were analyzed for the quantity of SEA present in the milk. The amount of SEA in the cartons varied from 94 to 184 ng with the average being 144 ng (mean = 139 +/- 45). The attack rate for vomiting among those who consumed more than one carton was greater (38.3%) than among those who consumed only one carton (31.5%) with the highest attack rate among those who consumed three or more cartons (44.4%).     

Heat transfer analysis of cheese cooling incorporating uncertainty in temperature measurement locations: Application to the industrial process

A cylindrical cheese product with an irregular cross sectional geometry is cooled by partial immersion in brine. It is essential to calculate the temperature–time history of the product during this cooling phase to ensure its microbiological safety. The heat transfer analysis is complicated by both the non-standard product geometry and the non-uniform surface heat transfer coefficients that prevail. The flotation behaviour of the cheese at the air/brine interface is analysed to determine the heat transfer areas exposed to each cooling fluid. A finite element model is developed to predict temperature histories at various points in the product and to determine the slowest cooling region in the product. The cooling performance of the cheese is also studied experimentally. Comparison of the theoretical and experimental temperature histories is complicated by uncertainty in the location of the thermocouples in the product. By statistically quantifying the imprecision in thermocouple position, the expected temperatures in each region of interest can be found from the thermal model by Monte Carlo sampling. With the model, the top region of the cheese stick has been shown to determine cooling time because the existence of the non-uniform boundary condition is significant in determining the evolution of temperature.