Effect of specific wavelengths on light-induced quality changes in Havarti cheese

The effects of exposure of slices of Havarti cheeses to monochromatic light of wavelengths 366 nm, 405 nm, and 436 nm, respectively, were studied by tristimulus colorimetry, solid-phase microextraction gas chromatographic analysis of volatiles, and open-end fluorescence spectroscopy. Having determined the photon fluxes of the three wavelengths by ferrioxalate actinometry, it was possible to quantify the effects of light exposure in an absolute manner. For all analyses, the most severe effects were caused by visible light, leading to colour bleaching, change in hue, riboflavin degradation, and formation of the secondary oxidation products hexanal, 1-pentanol, and 1-hexanol. Apparent quantum yields for formation of hexanal and 1-pentanol were found to be insignificantly different for 405 nm and 436 nm exposures, having values of (3-5) x 10(-5) mol x einstein(-1) and (9-13) x 10(-5) mol x einstein(-1), respectively. These compounds were not formed when exposed to 366 nm light. In contrast, 1-hexanol was formed when exposing cheese to all three wavelengths, resulting in apparent quantum yields of (2-6) x 10(-5) mol x einstein(-1). The results obtained are discussed in relation to the interplay between inherent product colorants, light sources, and transmission characteristics of the packaging materials.     

Changes in rumen bacterial and archaeal communities over the transition period in primiparous Holstein dairy cows

In the present study, we hypothesized that the rumen bacterial and archaeal communities would change significantly over the transition period of dairy cows, mainly as an adaptation to the classical use of low-grain prepartum and high-grain postpartum diets. Bacterial 16S rRNA gene amplicon sequencing of rumen samples from 10 primiparous Holstein dairy cows revealed no changes over the transition period in relative abundance of genera such as Ruminococcus, Butyrivibrio, Clostridium, Coprococcus, and Pseudobutyrivibrio. However, other dominant genus-level taxa, such as Prevotella, unclassified Ruminococcaceae, and unclassified Succinivibrionaceae, showed distinct changes in relative abundance from the prepartum to the postpartum period. Overall, we observed individual fluctuation patterns over the transition period for a range of bacterial taxa that, in some cases, were correlated with observed changes in the rumen short-chain fatty acids profile. Combined results from clone library and terminal-restriction fragment length polymorphism (T-RFLP) analyses, targeting the methyl-coenzyme M reductase α-subunit (mcrA) gene, revealed a methanogenic archaeal community dominated by the Methanobacteriales and Methanomassiliicoccales orders, particularly the genera Methanobrevibacter, Methanosphaera, and Methanomassiliicoccus. As observed for the bacterial community, the T-RFLP patterns showed significant shifts in methanogenic community composition over the transition period. Together, the composition of the rumen bacterial and archaeal communities exhibited changes in response to particularly the dietary changes of dairy cows over the transition period.     

Electrical stimulation of pigs-effect on pH fall, meat quality and Cathepsin B+L activity

This work was performed to evaluate the effect of electrical stimulation (ES) on pH fall and meat quality of LD and BF in Danish halothane free pigs stunned with CO(2). ES resulted in a significant drop in pH of 0.3 units in both LD and BF and 3 h lairage resulted in 0.1 units lower pH at 20 min post mortem. Lairage time did not affect and did not interact with the effect of ES on any of the measured meat quality parameters. ES did not affect the ultimate pH in LD, BF, SM and SC or internal reflection value in LD. However, ES caused higher internal reflection and drip loss in BF and increased the PSE frequency in LD (2 to 7%) and in BF (2 to 49%). The frequency of PSE areas in the centre of SM was 70% for ES pigs compared to 9% for control pigs. ES and ageing improved the tenderness and reduced the hardness in LD as well as shear force of unaged BF. The effect of ES on tenderness and hardness was approximately half the effect of ageing, but the effect of ES and ageing were additive. ES significantly increased the activities of cathepsin B+L in the myofibrillar fraction, but there were no differences in proteolytic activity in the other fractions. It is concluded that ES improves tenderness in LD and BF, but has a negative effect on the quality of BF and SM. Therefore ES is not an economically attractive alternative for improvement of tenderness in LD compared to ageing in Danish pigs. ?     

Glycogen content, buffering capacity and resting pH in live muscles of pigs of different halothane genotypes (a pilot project)

The development of PSE (pale, soft and exudative) meat is characterized by a rapid decrease in pH post-mortem and/or a low ultimate pH. We investigated some physiological properties of the live muscle (the glycogen content, the non-bicarbonate buffering capacity and 'resting pH'), which could influence both the decrease in pH and the ultimate pH. Measurements were performed on three halothane genotypes, hal(N)hal(N), hal(N)hal(n) and hal(n)hal(n), with their known predispositions for PSE meat. It was demonstrated that the glycogen content in both the groups of double recessive and heterozygous individuals was higher than the levels in the group of homozygous dominant pigs. No difference was found in non-bicarbonate buffering capacity between the groups. The groups with the highest glycogen levels also had the lowest 'resting pH' values. The results indicate that measurement of glycogen content in vivo may be superior to the halothane test in detecting PSE-prone individuals. The lower pH values of carriers of the hal(n) gene further indicate that the characteristic rapid decrease after slaughter may not be as fast as generally accepted, as even very low pH values can be observed in the muscles of live pigs.     

Tissue degradation,amino acid liberation and bacterial decomposition of bulk stored capelin

Bulk stored capelin with high contents of feed in the gut is easily solubilised because of high proteolytic activity. The amino acids most quickly liberated are arginine, serine, histidine, leucine, lysine and tyrosine; glycine, aspartic acid and glutamic acid are liberated at a slower rate. Bacterial activity results in a rapid and considerable decrease in total amounts of tyrosine, lysine, serine, arginine and histidine. The main products formed by bacterial decomposition of lysine, histidine and arginine are cadaverine, histamine and putrescine, respectively. Storage of capelin in the presence of antibiotics increased the amounts of free amino acids and total amino acids. After 10 days' storage at 6°C, about 30% of the total amino acid content in fish treated with antibiotics were fee amino acids.     

The incidence of male hermaphroditism in girls with inguinal hernia

The incidence of male hermaphroditism in girls with inguinal hernias is estimated to be 1.4 per cent. From 1961 to 1972, 340 girls were admitted to the Department of Surgery at St. Josephs Hospital for hernial repair. One hundred and two patients had menstruated prior to the follow-up study. Buccal smears from the remaining patients were examined for Y chromatin-positive cells. We observed a zero per cent rate of male hermaphroditism, which is not significantly different from the aforementioned frequency, p greater than 0.05. Large scale prospective studies must be available before any conclusion can be drawn as to whether or not determination of the genetic gender prior to hernial repair in girls should be conducted as a routine procedure.     

The elastic cartilage in the normal rat epiglottis. I. Fine structure

Unilateral electrolytic lesions of the locus coeruleus in rats result in spontaneous ipsiversive rotation, which is then replaced by contraversive rotation. One week after lesioning, when spontaneous turning ceases, apomorphine and d-amphetamine elicit contraversive circling behaviour, which was not affected by noradrenergic receptor blockade but was abolished by dopamine receptor blockade. The drug-induced contraversive circling response was also reproduced by piribedil but not clonidine. Combined unilateral electrolytic locus coeruleus and substantia nigra lesions on the same side resulted in apomorphine- and d-amphetamine-induced ipsilateral rotational behaviour which was indistinguishable from that seen with substantia nigra lesions alone. In rats with unilateral locus coeruleus lesions, the dose of intrastriatally injected apomorphine required to produce circling was less on the lesioned than the non-lesioned side. Direct injection of noradrenaline into one substantia nigra caused contraversive circling. Direct injection of phenoxybenzamine into one substantia nigra followed by apomorphine caused ipsiversive circling. The results suggest that the circling behaviour seen after unilateral locus coeruleus lesions depends on an asymmetry of striatal dopamine receptor activity and are consistent with a proposed coeruleus-nigral noradrenergic pathway, which enhances impulse flow in the dopaminergic nigrostriatal system.     

The critical transmural pressure of the abirway

The critical transmural pressure (Ptm) is defined as the transmural pressure of the airway at the site where and when flow is limited during a forced expiration. According to the presented theory, the maximal expiratory flow (Vmax) can be calculated from the relation between Ptm and the corresponding cross-sectional area of the airway (A). By means of a pitot-static tube, Ptm-A curves were constructed for several locations in the elastic airway of a mechanical model. From these curves local Vmax was calculated at different values of Ptm and compared with actual flow, i.e. measured Vmax for the entire airway. In the downstream part of the airway, the actual flow equalled calculated Vmax at most Ptm values. The site of flow limitation, being the most upstream point where actual flow equals calculated local Vmax could therefore be located. Theory and experiments showed positive as well as negative Ptm not influenced by change in upstream or downstream resistance. Flow limitation could therefore be initiated at distending as well as compressing pressures across the wall of the airway. V was regarded as a function of Ptm and the elastic recoil pressure of the lung (Pel). Measured and calculated iso-Pel, Ptm-V curves agreed well with one major exception: when Ptm less than Ptm measured curves were distorted due to a concomitant downstrean compression of the collapsible airway.     

Mixed-species biofilms in the food industry: Current knowledge and novel control strategies

Abstract

Attachment of microorganisms to food contact surfaces and the subsequent formation of biofilms may cause equipment damage, food spoilage and even diseases. Mixed-species biofilms are ubiquitous in the food industry and they generally exhibit higher resistance to disinfectants and antimicrobials compared to single-species biofilms. The physiology and metabolic activity of microorganisms in mixed-species biofilms are however rather complicated to study, and despite targeted research efforts, the potential role of mixed-species biofilms in food industry is still rather unexplored. In this review, we summarize recent studies in the context of bacterial social interactions in mixed-species biofilms, resistance to disinfectants, detection methods, and potential novel strategies to control the formation of mixed-species biofilms for enhanced food safety and food quality.     

Antiviral activity of donkey milk protein fractions on echovirus type 5

Antiviral activity of Ragusano donkeys' milk proteins was investigated for the effect on echovirus type 5, known to infect the gastrointestinal tract of humans. Three protein fractions were tested; casein (CN), whey protein (WP) and a low molecular whey protein fraction (LWP; <30,000 Da). The antiviral activity of WP and LWP was tested on echovirus type 5 at three concentrations (1, 5 and 10 mg mL^?1); CN was assessed only at the lower concentration. All donkey milk protein fractions showed significant inhibition on virus replication at the concentration of 1 mg mL^?1, and both WP and LWP fractions showed significant inhibition on the virus replication at all concentrations tested. The strongest antiviral effect was observed for the WP fraction. These findings show that the different whey proteins in donkey milk, probably acting in synergy, exert antiviral activity on echovirus 5 and might contribute to prevent gastrointestinal virus infections in humans.