Factors affecting the suitability of aluminium-foil trays for microwave oven heating: Comparison with plastic trays

The suitability of shallow aluminium trays (thickness of food layer 20 mm) for heating of different casseroles in microwave ovens was extensively studied. The effects of the shapes and sizes of the trays, the initial temperature and the type of oven were tested systematically for the usability of the aluminium trays, the required heating time and heating results. The results were compared with those obtained using CPET trays. It was also investigated whether incorrect placing of an aluminium tray in the oven would cause risk situations, such as arcing. It was found that, when used correctly, aluminium trays are suitable for heating of both frozen and chilled casserole products in a microwave oven. Especially in the case of frozen products, aluminium trays are more suitable than plastic trays. The post-heating quality can be improved by packaging of foods in an aluminium tray instead of a plastic tray. The shape of the trays also has an important role. Aluminium trays are better suited than plastic trays for heating in a combination oven.     

Analysis of regioisomers of triacylglycerols of northern currant seed oil by tandem mass spectrometry

Currant oils have special health properties due to their moderate contents of α‐linolenic, γ‐linolenic and stearidonic acids. The distribution of fatty acids (FA) in the triacylglycerols (TAG) may affect the beneficial effects. Seed oils of wild northern red currant (NRC) (Ribes spicatum L.) from Northern Finland and of wild alpine currant (AC) (R. alpinum L.) from the South‐West coast of Finland were investigated. The purified TAG were analysed by tandem mass spectrometry by applying the ammonia negative ion chemical ionisation – collision‐induced dissociation method. Molecular weight fractions rich in C18:3 FA and C18:4 FA were investigated. Of the total oil, the molecular weight species 54:7 (ACN:DB), 54:8 and 54:9 were more abundant in NRC than in AC, being 21.0%, 15.8%, 7.4% and 16.2%, 11.2%, 4.8%, respectively (p <0.05). The species 52:6 was more abundant in AC (3.1%) than in NRC (2.6%) (p <0.05). The preferential order of FA to be in the sn‐2 position in both berries was typically C18:1 > C18:2 > C18:4 > C18:3. No difference was observed between relative locations of C16:0 FA and C18:3 FA in either of the oils. Within the TAG consisting of FA combinations C18:3/C18:3/C18:1 (54:7), C18:1 was more preferentially in the sn‐2 position (p <0.05) in AC (93.2%) than in NRC (74.6%), and in the case of C18:3, the preference was vice versa. Within the molecular weight species 54:9, FA combination C18:4/C18:3/C18:2, linoleic acid preferentially occupied the secondary position (p <0.005) in both berries, and the proportion of the TAG regioisomer pair sn‐C18:3‐C18:4‐C18:2 + sn‐C18:2‐C18:4‐C18:3 was more abundant (30.2%) in NRC than in AC (15.3%). Within the TAG species 52:6, proportions of all the existing combinations, C16:0/C18:3/C18:3, C16:0/C18:4/C18:2 and C16:1/C18:3/C18:2, varied between the two berry species (p <0.005).     

Volatile compounds of Baltic herring analysed by dynamic headspace sampling–gas chromatography–mass spectrometry

European Food Research and Technology - The effect of storage time at 6&;nbsp;°C on the volatile compounds of Baltic herring was studied using the dynamic headspace–gas...     

Influence of different pretreatments on the accessibility of transglutaminase and tyrosinase to wool fibre proteins

Wool fibres are subject to a variety of industrial chemical treatments prior to finishing processes. The influence of such treatments on subsequent enzymatic treatments is still poorly characterised, but its importance is paramount to achieve maximal efficiency of enzymatic action on the fibres. The effect of such treatments on wool fibre structure and their significance on the accessibility of the enzymes transglutaminase and tyrosinase to their target amino acids within wool proteins was investigated. These enzymes are of great interest due to their potential as protein cross‐linkers and their capability to covalently graft beneficial compounds onto proteins. The accessibility of target amino acids was assessed using specific peptides tagged with fluorescent probes, followed by epifluorescence or confocal microscopy. Differences in the action of the different chemical pretreatments were found, with a treatment with permonosulphuric acid resulting in the greatest level accessibility to both enzymes, followed by chlorination and plasma treatments. This was confirmed by the increase in tensile strength of treated wool observed in the enzyme‐treated yarns. This work illustrates that the accessibility of these enzymes to their target aminoacids in solid substrates such as wool is key for their action and to achieve the desired property modifications. The techniques used have the advantage of permitting the visual monitoring of the diffusion of the active enzymes through the wool fibre structure and to relate this to the extent of enzymatic reaction. Crucially, this will allow an informed choice of the best wool processing stage at which to introduce such enzyme treatments.     

Shelf-life of prepeeled potato cultivated, stored, and processed by various methods

The present study was aimed to investigate the effects of indigestible dextrin and polydextrose, soluble dietary fibers with low molecular weight, on lipid metabolism and disaccharidase activities of intestinal mucosa in rats fed a high sucrose diet. Their effects were compared with those of well-known soluble fibers, pectin, and guar gum, and also with an insoluble fiber, cellulose. Dietary fibers added to diets at the 5% (w/w) level were alpha-cellulose, pectin, guar gum, indigestible dextrin, and polydextrose. Male Sprague-Dawley rats were given free access to test diets for 6 weeks. Body weight gain was the lowest in rats fed guar gum, the highest in rats fed cellulose, and in-between in rats fed other diets. Although guar gum, pectin, and indigestible feeding dextrin had lower plasma lipid values than cellulose feeding did, the differences were statistically insignificant. Liver triglyceride of the guar gum-fed group was about a third that of the cellulose-fed group, but although those of rats fed polydextrose, indigestible dextrin, and pectin were lower than that of cellulose, the differences were insignificant. Liver cholesterol and phospholipid concentrations were similar among groups. Daily fecal excretion of total lipid, cholesterol, and bile acids were highest in rats fed guar gum, followed by pectin-fed and cellulose-fed rats, and the lowest in rats fed indigestible dextrin and polydextrose. Jejunal sucrase activity was low in the order of guar-gum, polydextrose, indigestible dextrin, pectin, and cellulose. The results indicate that the hypolipidemic effect of soluble dietary fibers would be lessened with reduction in molecular weight, but that the lower sucrase activity by soluble fibers with low molecular weight might be beneficial for hypoglycemic effect.     

Shelf life of sliced raw potatoes of various cultivar varieties--substitution of bisulfites

Treatment of colorectal liver metastases with the HSVtk/GCV approach and adenoviral vectors is highly toxic. We present a nontoxic alternative using the cell type-specific CEA promoter instead of the widely used hCMV immediate-early promoter to drive tk gene expression in the context of a recombinant adenovirus. Analysis of CEA promoter-dependent tk gene expression showed significant activity of this promoter in several human and rat tumor-derived cell lines but not in rat primary hepatocytes and in mouse liver, whereas the CMV promoter was highly active in all cell types and tissues investigated. CEA promoter-dependent tk gene expression was sufficient to kill 100% of cancer cells in vitro, even if less than 10% were infected by the adenoviral vector, indicating a significant bystander effect. Moreover, treatment of subcutaneous tumors in SCID mice with Ad.CEA-tk led to a several-fold reduction of tumor growth, and tail vein injection of a high dose of Ad.CEA-tk caused no side-effects in the liver. The CMV promoter was more potent than the CEA promoter in mediating GCV sensitivity to cancer cells in vitro and in vivo, but even a 20-fold reduction of the dose of Ad.CMV-tk did not prevent its liver cell toxicity after systemic application to mice and still resulted in the death of all animals within 4 days after the start of GCV treatment. These results indicate that restriction of tk gene expression to tumor cells in the liver prevents systemic toxicity. Moreover, the CEA promoter is a safe and efficient tool for tumor cell-specific expression of suicide genes in the liver.     

Effect of plastic coating on the sensory properties of fibreboard-based packaging materials in microwave oven heating

The effects of the type and thickness of plastic coating on the migration of off-odours and off-flavours from fibreboard materials to certain model foodstuffs were studied in microwave oven heating. Correlations between sensory, physical and chemical properties of fibreboard materials were also determined. The plastic coating served as a very good barrier to the transfer of off-flavours into foodstuffs. Polyester coating prevented the migration of off-flavours, whereas polyethylene and polypropylene were effective only in certain cases. With the last two plastics, the thickness of the coating layer also affected the amount of off-flavours migrating. Generally, the sensory properties of the materials did not correlate with either the melting behaviour of the plastic coating or the amount of volatile compounds generated.