Effects of the CSN1A(G) allele on the clotting time of cow milk and on the rheological properties of rennet-curd

The aim of this research was to study the effects of the CSN1A(G) allele on the main rennet coagulation properties of milk. The study was carried out on individual milk samples with low alphas1-casein obtained from 19 Italian Brown cows heterozygous for the CSN1A(G) allele (seventeen CSN1A BG and two CSN1A CG) from four herds in the province of Parma (Italy). Control cows (sixteen CSN1A BB and three CSN1A BC) giving milk with normal alphas1-casein levels were chosen from within the same herds in order to establish pairs of cows with identical environment and management conditions, and comparable lactation stages and numbers. Individual milk samples from single pairs of cows with somatic cell counts and lactose and chloride levels within the normal ranges were collected and analysed in parallel. Rennet coagulation properties of milk were analysed using Formagraph and Gel Tester. Milk from low alphas1-casein cows was characterized by lower casein content, lower titratable acidity and a higher proportion of kappa-casein in total casein. The clotting time of this milk was approximately 23% lower than that obtained with milk from normal alphas1-casein cows. Rennet curd from low alphas1-casein milk was obtained more rapidly and had a higher final firmness: curd-firming time was approximately 35% lower and curd firmness measured 30 min after rennet addition was approximately 27% higher compared with that for normal alphas1-casein milk. In addition, curd from low alphas1-casein milk had a higher resistance to compression. These results suggest that, although a role for the CSN2 locus cannot be definitely excluded, the CSN1A(G) allele can considerably affect the main rennet coagulation properties of milk.     

Ultrasonic and Microscopic Investigation of Impact Damage in GFRP Composites

Abstract

Some aspects of ultrasonic evaluation of impact damage in glass fiber-reinforced plastic (GFRP) composites are discussed in this paper. First and foremost, results of a microscopic investigation are reported which illustrate the structural properties of GFRP composites and show that, contrary to the assumption used in the current literature, no delamination occurred in the samples examined in this work when the energy of impact was lower than 9 J. Second, a simple ultrasonic approach to assess the maximum spatial extent of the damaged volume is presented. The evaluation of the damage spatial extent obtained by this method is shown to correlate well with that recovered by a direct microscopic investigation. Finally, in view of the findings obtained by the microstructural analysis, a brief discussion is presented which reviews the properties a nondestructive method should possess in order to provide reliable quantitative assessment of impact damage in GFRP composites.     

Free fatty acid profile of Parmigiano–Reggiano cheese throughout ripening: Comparison between the inner and outer regions of the wheel

From each of twenty wheels of Parmigiano–Reggiano cheese of different ages (1–24 months), samples representative of the inner part (I, 10 cm from the round side and 7 cm from the flat side) and of the outer part (O, the rest of the cheese after removing the rind) were collected. For each sample, free fatty acids (FFAs, expressed as mg kg⁻¹ cheese fat) were determined by quantitative capillary gas chromatography. In 18- and 24-month-old cheese, total levels of FFAs (as sum of individual FFAs) were significantly (P ≤ 0.05) higher in O than I, whereas no differences between regions were observed in 1-, 6- and 12-month-old cheeses. In terms of short (C4–C8) and medium (C10–C14) chain FFAs, levels in the outer regions were higher (P ≤ 0.05) than inner regions for cheeses from 6- to 24-month-old. The content of long-chain FFAs (C16–C18:2) was higher in O than I in 18- and 24-month-old cheeses.     

Rapid diagnosis of cytomegalovirus encephalitis in patients with AIDS using in situ hybridisation

AIMS: To evaluate the presence of cytomegalovirus (CMV) DNA in the cerebrospinal fluid of patients with AIDS and suspected viral encephalitis using an in situ hybridisation assay with digoxigenin labelled CMV DNA probes. METHODS: The presence of CMV DNA was evaluated in cerebrospinal fluid cells of 10 patients with AIDS using in situ hybridisation. The positivity of CMV DNA was confirmed by the presence of CMV induced antigens in the same specimens. The presence of CMV DNA and CMV induced antigens was also analysed in peripheral blood leucocytes. The time required to perform the in situ hybridisation assay was about eight hours. RESULTS: The in situ hybridisation assay was sensitive, specific, and provided good resolution. Six patients proved positive for the presence of CMV DNA in CSF cells and all six also proved positive for CMV DNA in blood leucocytes. Of the six CMV positive patients, five were treated with specific antiviral drugs: of these, one died during the treatment while four clinically recovered after one month of treatment. CONCLUSIONS: The in situ hybridisation assay using digoxigenin labelled CMV DNA probes can be used as a valuable diagnostic test for the detection of CMV DNA in the cerebrospinal fluid cells of patients with suspected CMV encephalitis and can therefore prompt adequate antiviral therapeutic intervention.     

Unfermented and fermented rooibos teas (Aspalathus linearis) increase plasma total antioxidant capacity in healthy humans

The aim of the study was to assess the effect of drinking rooibos tea (Aspalathus linearis) on total antioxidant capacity (TAC), lipid triacylglycerols, cholesterol and glycaemia plasma levels in humans. In vitro, unfermented rooibos tea displayed a 28% higher value of TRAP than did the fermented beverage. An acute intervention study, cross-over design, was performed, with 15 healthy volunteers who consumed 500 ml of either water, unfermented or fermented rooibos teas. Plasma antioxidant capacity increased significantly with both teas, reaching a peak at 1 h post-consumption (+6.6%, p < 0.05 fermented tea; +2.9%, p < 0.01 unfermented tea). No changes in triacylglycerols, cholesterol or uric acid were observed with any of the treatments. A transitory increase in glycaemia at 30 min was linked to glucose upload. The data show that rooibos teas represent a source of dietary antioxidants in humans.     

Composition, coagulation properties and Parmigiano-Reggiano cheese yield of Italian Brown and Italian Friesian herd milks

The authors report the results of a study aimed at the comparison of the basic chemical composition, the main protein fractions distribution, rennet coagulation properties and Parmigiano-Reggiano cheese yield of vat milk from Italian Brown and Italian Friesian herds. Parmigiano-Reggiano cheese factories which manufacture milk separately from Italian Brown herds and Italian Friesian herds were used in the study. Thirteen cheesemaking trials were performed at 10 different commercial cheese factories. The study was carried out from March to October 2003. For each cheesemaking trial in each factory, approximately 1100 kg milk from Italian Brown cows and from Italian Friesian cows were processed in parallel. The animals involved in the study came from farms with comparable management practices, size, location, number of lactation and days in milking. Each vat contained milk obtained by combining milk collected during the evening milking (partially skimmed milk by natural creaming) and the following morning milking (full-cream milk), from at least 2 dairy herds. Milk from Italian Brown cows is characterised by a higher casein content (27.1 v. 23.7 g/kg; P < or = 0.0001) than Italian Friesian cows' milk. Curd firming time (k20) of Italian Brown cows' milk was markedly lower than that of Italian Friesian cows' milk (6.6 v. 10.0 min; P < or = 0.001). This implies a higher rate of aggregation of para-casein micelles for Italian Brown cows' milk. The coagulum of Italian Brown cows' milk had better rheological properties and lower losses of fat in the cheese whey. Parmigiano-Reggiano cheese yield at 24 h was also higher for Italian Brown cows' milk, + 0.99 kg cheese for every 100 kg vat milk.     

Ultrasonic wave scattering from rough,imperfect interfaces. Part I. Stochastic interface models

A theoretical model for ultrasonic wave scattering by geometrically irregular and imperfectly bonded interfaces is presented. In Part I, the normal stiffness of interfaces formed by the partial contact of solids with rough surfaces is estimated for two models of contacting surfaces with random roughness in one dimension only. The first model considers nonconforming surfaces with a single-scale of roughness, while double-scale roughness characterizes the surfaces of the second model, which are conforming at the large scale and nonconforming at the smaller scale. The surfaces' profiles are described by Gaussian probability and spectral densities. The surfaces at each contact are modeled by two cylinders under a compressive load and the normal stiffness per unit area of the interface is evaluated by averaging the stiffness of all the contacts, assuming they do not interact with each other. It is shown that the smaller the roughness, the softer the interface; the larger the autocorrelation length, the softer the interface; and the smaller the initial aperture, the stiffer the interface. Furthermore, interfaces described by the second model appear much stiffer than those described by the first model. The interface characterizations and normal stiffness models developed in Part I will be used in Part II to study the scattering of ultrasonic plane waves by such an interface.     

Ultrasonic and Microscopic Investigation of Impact Damage in GFRP Composites

Some aspects of ultrasonic evaluation of impact damage in glass fiber-reinforced plastic (GFRP) composites are discussed in this paper. First and foremost, results of a microscopic investigation are reported which illustrate the structural properties of GFRP composites and show that, contrary to the assumption used in the current literature, no delamination occurred in the samples examined in this work when the energy of impact was lower than 9 J. Second, a simple ultrasonic approach to assess the maximum spatial extent of the damaged volume is presented. The evaluation of the damage spatial extent obtained by this method is shown to correlate well with that recovered by a direct microscopic investigation. Finally, in view of the findings obtained by the microstructural analysis, a brief discussion is presented which reviews the properties a nondestructive method should possess in order to provide reliable quantitative assessment of impact damage in GFRP composites.