Solar Dryer for Powder Drying

A natural circulation solar dryer for drying products in the form of powder has been developed. It is of modular design and aperture area of one module is 3.34 m². A new concept of moveable glazing has been introduced for ease in loading and unloading. Air entering the dryer moves in a zig-zag path as it flows over the product and under each tray before leaving from the top. There is a provision to dry the product under shade. Also, the dryer can be dismantled and stored in a room during off-season. The dryer was tested to dry Di-calcium phosphate (DCP) at Ludhiana (31°N). The average drying efficiency for a batch was found to be 54.0%. The cost of drying DCP using this solar dryer was 0.56 Rupees per kg of dried DCP as compared to 1.94 Rupees per kg of dried DCP for a wood-fueled industrial dryer. In comparison to a solar tunnel dryer for DCP drying, the initial investment per kilogram of the dried DCP, floor area per kilogram of wet DCP, and cost of drying per kilogram of dried DCP for this dryer was reduced by 7.1%, 67.2%, and 16.4% respectively.     

Depth from image focus methods for micro-manufacturing

The analysis of industrially important electronic components of micro dimensions such as thin film transistor liquid crystal display color filter is of fundamental importance in consumer electronics. Three dimensional (3D) visualization, size, area, and surface roughness are important parameters for the analysis of micro components. For this purpose, the devices equipped with active but expensive depth estimation techniques are commonly used. However, these can be replaced by inexpensive passive methods. In this paper, we propose an inexpensive and simple system for the analysis of micro components. It comprises a CCD camera mounted on a conventional microscope and a passive optical method for 3D shape recovery. To improve the accuracy of the system, we introduce an accurate depth estimation scheme by using cubic degree Bezier–Bernstein polynomial. The proposed system is tested by using image sequences of synthetic and real objects. The experimental results demonstrate the usefulness and effectiveness of the proposed system for the analysis of micro size electronic components.     

Structural,thermal, and antibacterial properties of chitosan/ZnO composites

This study presents the influence of zinc oxide (ZnO) on the structural, thermal, and antibacterial characteristics of chitosan. The chitosan composites containing different concentrations of ZnO (0.5–2 mass ratio with respect to chitosan) were prepared using sol‐cast transformation method. Fourier‐transform infrared spectra and X‐ray diffraction patterns revealed chemical interactions between the chitosan and ZnO in the composites that became more evident at higher concentrations of filler. The composites exhibited significantly lower degradation rate and higher thermal stability than that of chitosan. When 50% mass loss is set as a point of comparison, the chitosan/ZnO (1:2) composite exhibited 143°C higher thermal stability compared with chitosan. Similarly, the composites exhibited biocidal activity to gram positive and gram negative bacteria. Furthermore, higher biocidal activity was possessed by chitosan/ZnO (1:1) composites. The current–voltage characteristics curves also depicted a significant increase in the value of current versus voltage at equimolar concentration of chitosan and ZnO. It can be concluded that the biocompatible, eco‐friendly and low cost chitosan/ZnO composite hydrogels can be used for food packaging and biomedical applications. POLYM. COMPOS., 35:79–85, 2014. © 2013 Society of Plastics Engineers     

Microbiological effects of hand washing at a beef carcass-breaking facility

The hands of workers in the carcass-breaking facility at a beef packing plant were sampled by rinsing. Total aerobes, coliforms, and Escherichia coli were enumerated for each sample. The numbers of bacteria recovered from duplicate groups of 25 hand samples collected before and after hands were washed with an antibacterial gel, rinsed in a disinfectant solution, washed with the gel and rinsed with the disinfectant, or washed in the disinfectant for 20 s were similar for samples collected before work began after breaks. The numbers of bacteria recovered from samples collected before and after hands were washed with the antibacterial gel and rinsed in the disinfectant solution were similar for samples collected after work as well. However, the mean numbers of aerobes recovered from the four groups of hand samples after work were all >6.5 log CFU per hand, while 9 of the 10 corresponding values for groups of hand samples collected before work were <6.5 log CFU per hand; the total numbers of coliforms recovered from three groups of hand samples collected after work were >4 log CFU/25 hands, while 9 of the corresponding values for groups of hand samples collected before work were <4 log CFU/25 hands. The total numbers of E. coli recovered from all groups of hand samples collected after work were >3.5 log CFU/25 hands, while 9 of the corresponding values for groups of hand samples collected before work were <3 log CFU/25 hands. Thus, although washing and/or rinsing apparently did not reduce the numbers of bacteria on hands, fewer bacteria were recovered from hands before than after work.     

The effects of residual oxygen concentration and temperature on the degradation of the colour of beef packaged under oxygen-depleted atmospheres

Samples of beef longissimus dorsi (LD), approximately 5 × 5 × 1 cm, were packaged in pairs under 10 litre volumes of N₂ or CO₂ containing O₂ at concentrations between 100 and 1000 ppm. The packaged samples were stored at temperatures of 5, 1, 0 or −1·5°C, for times between 4 and 48 h. Samples of beef psoas major (PM) were packaged under N₂ or CO₂ containing O₂ at between 100 and 600 ppm, and stored at −1·5°C for 24 or 48 h. After storage, each sample was assessed for colour deterioration and discoloration, and for the fraction of metmyoglobin in the surface pigment.

The results obtained with N₂ and CO₂ atmospheres were similar. The colours of all LD samples had deteriorated after 4 h storage at 5 or 1°C, although the degree of deterioration increased with increasing O₂ concentration. All LD samples stored for 12 h at 5 or 1°C were extensively discoloured, with metmyoglobin fractions generally exceeding 60%, but those stored at −1·5°C for 48 h or less, under O₂ concentrations ≤ 400 ppm had undergraded colours. The colours of some LD samples stored at −1·5°C under about 600 ppm of O₂ were also undergraded, but the colours of samples stored under 800 or 1000 ppm had deteriorated by 24 h. The colours of LD samples stored at 0°C under > 200 ppm had deteriorated after 24 h storage, and the colours of samples stored under 100 ppm O₂ had deteriorated after 48 h storage. All PM samples were wholly discoloured after storage at −1·5°C. Evidently, the colour of beef muscle of high colour stability is resistant to degradation by atmospheres containing < 600 ppm of O₂ when the meat is stored at sub-zero temperatures, but not when the storage temperature is at or above 0°C. Beef muscle of low colour stability, such as the PM, will discolour at all low concentrations of O₂ irrespective of the storage temperature.     

Metabolism of BTEX and naphtha compounds to methane in oil sands tailings

Naphtha, comprising low molecular weight aliphatics and aromatics (C3-C14), is used as a diluent in processing of bitumen from oil sands. A small fraction (<1%) is lost to tailings waste and incorporated into mature fine tailings (MFT). BTEX (benzene, toluene, ethylbenzene, and xylenes) and whole naphtha were assessed for biodegradation under methanogenic conditions using MFT from an oil sands tailings settling basin. MFT spiked with 0.05-0.1% w/v of BTEX compounds produced up to 2.1 (+/-0.1) mmol of methane during 36 weeks of incubation. Metabolism of 0.5-1.0% w/v naphtha in MFT yielded up to 5.7 (+/-0.2) mmol of methane during 46 weeks of incubation. Gas chromatographic analyses showed that BTEX degraded in the sequence: toluene > o-xylene > m- plus p-xylene > ethylbenzene > benzene. Only 15-23% of whole naphtha, mainly n-alkanes (in the sequence: nonane > octane > heptane) and some BTEX compounds (toluene > o-xylene > m-xylene), was metabolized. Other naphtha constituents, such as iso-paraffins and naphthenes, remained unchanged during this period. These results suggest that the microbial communities in the MFT can readily utilize certain fractions of unrecovered naphtha in oil sands tailings and support methanogenesis in settling basins. Current study findings could influence extraction process, MFT management, and reclamation options.     

Muscle composition of steers treated with the β-agonist, cimaterol

The effect of the β-adrenergic agonist, cimaterol, on the nature and amount of collagen in three individual muscles (Longissimus dorsi, Vastus lateralis and Semitendinosus) from young steers was investigated.

β-Agonist-treated animals showed similar rates of liveweight gain to those of control animals but the weight and protein content of the Longissimus dorsi and Vastus lateralis muscles were significantly increased (muscle weights 1216 versus 1494 g, P < 0·05; 514 versus 642 g, P < 0·01, respectively, for control and cimaterol animals). The Semitendinosus muscle, however, showed no significant increase in weight or protein content (P > 0·05).

The total collagen content and the proportion of heat-soluble collagen varied considerably between muscles, but no significant muscle × treatment interactions were detected (P > 0·05). Cimaterol treatment reduced total muscle collagen content (controls 15·2, cimaterol 12·5mg/g fresh tissue, P < 0·05) and also reduced the percentage of heat-soluble collagen (controls 18·9%, cimaterol 13·0%, P < 0·05).     

Design, fabrication, and testing of a returnable, insulated, nitrogen-refrigerated shipping container for distribution of fresh red meat under controlled CO2 atmosphere

In today's market, fresh red meat is cut and packaged at both the wholesale and retail level. Greater economies could result if the wholesaler prepared all consumer cuts centrally, but the short storage life of meat limits distribution. Use of CO₂-controlled atmosphere, master packaging, and strict temperature control (−1.5±0.5°C) can enhance storage life and, therefore, distribution ease. An insulated shipping and storage container was designed and tested for its suitability to distribute master-packaged meat. Shelves in the container supported 36 master trays (508 × 381 × 60 mm), with the source of refrigeration being injected liquid nitrogen (N₂). Electric fans dispersed the N₂ gas throughout the container. To reduce costs, 36 saline water bags (10% w/v NaCl) were used to thermally simulate the meat. Temperatures of 20 bags were recorded during storage experiments. The container was tested at outside temperatures of 15, 0 and −15°C with 4 internal fans and at 30°C with 2, 4 and 6 fans. In all instances, bags cooled from 10°C to an equilibrium temperature of −1.5°C within 5.5 h. Minimum equilibrium temperatures during any 8 h trial were −2.6, −2.0 and −2.0°C for 2, 4 and 6 fans, respectively. Correspondingly, maximum temperatures were −0.2, −0.7 and −0.3°C. Initial chilling of the product required, on average, 19 kg of N₂, while equilibrium was maintained at a N₂ consumption rate of 5.5, 4.0, 2.6 and 0.93 kg/h at outside temperatures of 30, 15 0 and −15°C, respectively, with 4 fans. The N₂ use for 2 and 6 fans was 5 and 6.3 kg/h, respectively, at an outside temperature of 30°C. During simulated power failure or when the N₂-tank ‘ran dry', temperatures in the container rose 0.9 and 2.0°C/h, respectively. When the door to the container was opened long enough to remove three trays, temperature was restored within 5 min. Convective heat transfer coefficients between saline water bags and circulating N₂ were in the range of 80–100, 115–135, and 140–155 W/(m²·K) for 2, 4 and 6 fans, respectively. Heat transfer to meat will be limited by conduction in master packaged meat if similar convection coefficients prevail.     

Decontamination of carcasses by vacuum-hot water cleaning and steam pasteurizing during routine operations at a beef packing plant

The microbiological effects of three operations for cleaning areas on dressed beef carcasses with vacuuming equipment which also applies hot water to the carcass, and of an operation for pasteurizing beef carcass sides with steam, were assessed. All four operations were routine in a commercial carcass dressing process. For each operation, swab samples were obtained from randomly selected carcasses, with a single sample being collected from each carcass, from a site selected at random from those affected by the operation. For the cleaning operations, 25 samples were obtained before and 25 after each operation. For the pasteurizing operation, 50 samples were obtained before and 50 after the operation. In addition, 50 samples were obtained from beef sides after the carcass cooling process which followed the pasteurizing operation. Total aerobic counts, coliforms and Escherichia coli from each sample were enumerated. The cleaning operations generally reduced the log mean numbers of bacteria on treated areas by ≤ 0.5 and had no discernible effect on the overall microbiological condition of the carcasses emerging from the process. The pasteurizing operation reduced the log mean numbers of total aerobic bacteria on carcasses by about 1, and the log mean numbers of coliforms and E. coli by > 2. The cooling process had no affect on the total counts, but further reduced the log mean numbers of coliforms and E. coli, apparently by about 1, to give beef sides from which E. coli were not recovered.     

The display life of retail packaged pork chops after their storage in master packs under atmospheres of N(2), CO(2) or O(2) + CO(2)

Commercial, bone-in pork loins were divided into four portions. One portion of each loin was vacuum packaged, then stored at -1.5 °C. The other portions were each divided into three chops, which were retail packaged. The retail packs were master packaged under atmospheres of N(2), CO(2) or O(2) + CO(2) (2:1, v/v), then stored at 2 °C. The pork was assessed after storage for up to 42 days. At each assessment, a vacuum pack and a master pack of each type, each containing product from the same loin, were withdrawn from storage. The vacuum packaged portion was cut into three chops, which were retail packaged. The chops from all packagings were displayed in a retail cabinet which maintained average air temperatures between 3 and 6 °C. The chops were assessed twice daily until they were judged to be of undesirable appearance. After storage for 1 or 2 days, the chops from all master packs appeared less desirable than the freshly cut chops. After all longer storage times, chops from N(2) and CO(2) atmospheres appeared as desirable as freshly cut chops, as did chops from O(2) + CO(2) that were stored for up to 16 days. However, chops stored under O(2) + CO(2) for 21 days appeared undesirable. Chops stored under N(2) or O(2) + CO(2) developed spoilage odours, after storage for 28 or 21 days, respectively. Bacteria were more numerous on the fat than on the muscle tissue. The numbers of bacteria were 10(7) cfu cm(-2) on the fat surfaces of chops stored under vacuum or N(2) for 42 days. The numbers of bacteria were 10(6) cfu cm(-2) on the fat surfaces of chops stored under CO(2) for 42 days or under O(2) + CO(2) for 21 days. At those times, only lactobacilli were isolated from chops stored under CO(2), but small or large fractions of enterobacteria were present in the flora on chops stored under vacuum or N(2), respectively, while the flora on chops stored under O(2) + CO(2) contained large fractions of Brochothrix thermosphacta and Gram negative, strictly aerobic, spoilage bacteria. After all storage times, chops cut from vacuum packaged portions remained of desirable appearance when displayed for 48 hr or longer. Chops stored under N(2) or CO(2) for between 2 and 35 days, or under O(2) + CO(2) for between 4 and 12 days, retained a desirable appearance during display for the same times as the freshly cut chops. Off-odours were apparent in chops after their display following storage under vacuum or CO(2) for 21 days, or under N(2) or O(2) + CO(2) for 12 days. The numbers of bacteria on the fat surfaces of chops spoiled by off-odours were ≥ 10(5) cfu cm(-2). The flora on chops removed from display were generally enriched for B. thermosphacta, enterobacteria and/or Gram negative aerobes as compared with the flora on the chops when they were removed from the storage packs. Those data indicate that the storage life of master packaged, display ready pork will probably be severely limited by the poor hygienic condition of commercial products, to little more than 1 week for product stored under N(2) or O(2) + CO(2) or < 3 weeks for product stored under CO(2).