Clarification and pasteurisation effects on monomeric anthocyanins and percent polymeric colour of black carrot (Daucus carota L.) juice

Black carrots (BCs) are a rich source of stable anthocyanins (ACNs). The purpose of this study was to evaluate the effects of clarification and pasteurisation on ACNs of black carrot juice (BCJ). Monomeric ACNs, ACN profile and percent polymeric colour were determined during processing of BCJ. While depectinisation and bentonite treatments resulted in 7% and 20% increases in monomeric ACN content of BCJ, respectively, gelatine–kieselsol treatment and pasteurisation resulted in 10% and 3–16% reduction. Percent polymeric colour decreased after clarification, but substantially increased in samples subjected to heat. ACNs of BCJ samples were identified by HPLC–MS. Unclarified BCJ contained cyanidin-3-galactoside-xyloside-glucoside-ferulic acid as the major ACN, followed by cyanidin-3-galactoside-xyloside-glucoside-coumaric acid, and cyanidin-3-galactoside-xyloside-glucoside. After depectinisation, two more ACNs (cyanidin-3-galactoside-xyloside and cyanidin-3-galactoside-xyloside-glucoside-sinapic acid) were also identified. These results indicated that depectinisation and bentonite treatment had positive effect on the colour of BCJ, while gelatin–kieselsol treatment and pasteurisation had negative effect.     

Role of pasteurisation heat treatments on rheological and protein structural characteristics of fresh egg pasta

The influence of egg pasteurisation and of thermal treatment(s) of fresh egg pasta on the protein network in the pasta were studied. Protein structural parameters were correlated with the physico-chemical and rheological characteristics of pasta. Twelve samples of fresh egg pasta were laboratory-produced, using raw or pasteurised whole egg, and either left untreated or submitted to one or two pasteurisation processes. Industrial pasteurisation of the eggs did not affect the protein network of pasta or its rheological and functional characteristics. Double thermal pasteurisation of egg pasta deeply influenced its structural characteristics, due to the formation of a tight protein network stabilised by disulfide bonds, in which ovalbumin plays an essential role. This tight protein network affected the cooking behaviour and the rheological properties of fresh egg pasta, decreasing weight increase upon cooking and break strain, while increasing break load and Young modulus. The indexes derived from these studies were applied to the characterisation of 24 commercial samples of fresh egg pasta. By using the Young modulus before and after cooking (rheological parameters) and protein solubility in buffer-saline (structural parameter), it was possible to discriminate three groups of samples as a function of the severity of their thermal treatment.     

Properties of Orange Juice with Supercritical Carbon Dioxide Treatment

The effects of supercritical CO₂ (SC-CO₂) on the microbiological, sensory (taste, odour, and colour), nutritional (vitamin C content), and physical (cloud, total acidity, pH, and °Brix) qualities of orange juice were studied. The CO₂ treatment was performed in a 1 litre capacity double-walled reactor equipped with a magnetic stirring system. Freshly extracted orange juice was treated with supercritical CO₂, pasteurised at 90°C, or left untreated. There were no significant differences in the sensory attributes and physical qualities between the CO₂ treated juice and freshly extracted juice. The CO₂ treated juice retained 88% of its vitamin C, while the pasteurised juice was notably different from the fresh juice and preserved only 57% of its vitamin C content. After 8 weeks of storage at 4°C, there was no microbial growth in the CO₂ treated juice.     

Hot water surface pasteurisation of lamb carcasses: microbial effects and cost-benefit considerations

Although hot water pasteurisation of carcasses is accepted as a general intervention in USA, this is not the case in Europe. The aims of this study were (i) to evaluate the microbiological effects of hot water pasteurisation of lamb carcasses, both after slaughtering and dressing and following subsequent chilling and storage; (ii) to discuss hot water pasteurisation from a public health and cost-benefit perspective; (iii) to discuss the benefits of hot water pasteurisation compared with use of separate meat processing streams for high-risk carcasses; (iv) to evaluate the use of recycled hot water in a hygienic context and in relation to EU regulations; and (v) to consider the technological and sensory aspects of hot water pasteurisation of lamb carcasses. Samples were collected from 420 naturally contaminated lamb carcasses, with 50% of the carcasses (n = 210) subject to hot water pasteurisation at 82 °C for 8 s immediately after slaughter. Surface swab samples from 4500 cm² areas on carcasses were collected at slaughter, after chilling for 24 h, and after chilling for five days. The microbial analyses included Escherichia coli, Enterobacteriaceae, Bacillus cereus, Clostridium perfringens and aerobic plate count (APC). A resuscitation step using Tryptone Soya Agar was included in the microbiological analyses. Hot water pasteurisation significantly reduced the levels of E. coli, Enterobacteriaceae, B. cereus and APC (all P < 0.001). E. coli colony forming unit (CFU) reduction was 99.5%, corresponding to a reduction of 1.85 log CFU per carcass. E. coli was isolated from 66% of control carcasses and from 26% of pasteurised carcasses. After 24 h storage, the reduction in E. coli was increased to 2.02 log, and after five days E. coli could not be isolated from the pasteurised carcasses. These results suggest that surface pasteurisation could be an important and efficient procedure (critical control point) for reducing generic E. coli and thereby shiga toxin-producing E. coli on carcasses, and thus the risk for disease among consumers. The recycled water had acceptable physical and chemical parameters and no spore-forming bacteria were detected. Although some carcass discolouration was observed, after 24 h the colour was acceptable. Our data provide relevant input for some of the data gaps regarding hot water pasteurisation and indicate that replacing the expensive system of separate processing of high-risk carcasses with hot water surface pasteurisation should be considered as a serious option.     

Effect of vacuum application on the physical,rheological and sensory characteristics of an artisanal ice cream

Four milk-based ice cream samples were produced by heating (65°C) the ingredients at different pressures (0.5, 1.0 bar) and times (5, 30 min). Overrun, melting behaviour, particle size, viscosity and sensory analysis were conducted for each time/temperature combination. The 5-min vacuum application resulted in a reduction of overrun and air bubbles size, whereas ice cream viscosity increased. Opposite outcomes were found for the sample treated with vacuum for 30 min, which also showed a significant fat globule size reduction (<3.0 μm). Sensory analysis revealed that the use of vacuum improved sweetness, milky and creamy sensations regardless the treatment times.     

Comparison of dynamic viscoelastic and physicochemical properties of pressurised and pasteurised longan juices with xanthan addition

Physical and biochemical properties of pressurised and pasteurised longan juices with various xanthan additions, such as viscoelastic behaviour, colour L (lightness), −a^∗ (greenness), b^∗ (yellowness), ΔE (total different colours) and BI (Browning Index) parameters, polyphenol oxidase (PPO) activity, ascorbic acid, gallic acid, ellagic acid, total phenols and antioxidant capacity (DPPH assay) were studied. Viscoelastic determination indicated that longan juice with 0.15% xanthan addition was optimal for a fruit drink. Colour parameters showed pressurised longan juice at 500 MPa was brighter and more transparent than fresh and other processed juices. PPO was completely inactivated in pasteurised juices, whereas in pressurised juices at 300 and 500 MPa, the activities were more than 100% and 95–99%, respectively. Bioactive components including ascorbic acid were significantly reduced according to treatment severities, whereas gallic and ellagic acids were relatively stable in all processed juices. Total phenols and DPPH radical-scavenging activity decreased significantly on pasteurisation, but were stable on pressurisation.     

Elucidation of key aroma enhancement in cloudy lemon juices by the addition of peel oil using GC–MS-Olfactometry

Volatile substances play a crucial role in the consumer preference of lemon juices. The effects of heat treatment and addition of lemon peel oil to lemon juice (Citrus limon Burm. cv. Kutdiken) on the aroma compounds were elucidated for the first time. Total phenolic, antioxidant activity, acidity, pH and colour properties were also studied. Results revealed that the aroma of the juice samples comprised mostly the terpene compounds. Limonene, γ-terpinene, β-pinene and α-pinene were the influential terpenes responsible for the distinctive odour of the lemon juice. The addition of the lemon peel oil increased the amounts of the aroma and aroma-active compounds. Besides, the heat treatment had a positive effect on the total phenolics and the antioxidant activity but it caused significant reduction of the aroma compounds. Sensory analysis revealed that the most preferred sample was the juice with lemon peel oil added after pasteurisation.     

The effect of pasteurisation temperature on the CLA content and fatty acid composition of white pickled cheese

In this study, the effect of pasteurisation temperature on fatty acid composition of cheese was investigated. The fatty acid composition of raw and different heat‐treated milk, salt and salt‐free cheese were determined using cheese made from raw milk at temperatures varying between 70 and 90°C for 5 min. Generally, C 16:0 palmitic acid was the major fatty acid present in all milk and cheese samples. C 18:1 t11 vaccenic acid was the major trans fatty acid (TFA) in all samples. C 18:2 cis‐9, trans‐11 (Rumenic acid) was the major CLA isomer in these samples. Pasteurisation temperatures had no effect on TFA, CLA and fatty acid composition of the milk and cheese samples.     

Characterisation of Macedonian white‐brined cheese: Effect of raw or heat‐treated caprine milk

This research analysed the use of raw and pasteurised milk in the production of Macedonian white caprine milk cheese. Pasteurisation resulted in a considerable decrease in the nitrogen fractions, urea‐polyacrylamide gel electrophoresis of caseins, peptide profiles and volatiles during the maturation period. Forty‐five volatile components were detected, including twelve acids, fourteen esters, six ketones, three alcohols, four terpenes and six other compounds. It was deduced that pasteurisation of milk for the manufacture of artisanal white‐brined cheese delayed the evolution of volatiles, which are related to the unique flavour of the cheese.     

Influences of storage time and temperature on the xanthophyll content of freeze-dried egg yolk

The influences of storage time, temperature (−18 or +20 °C, both in the dark), and prior pasteurisation on the xanthophyll content of freeze-dried egg yolk were investigated. After six months of storage, the synthetic xanthophylls all-E-canthaxanthin and β-apo-8-carotenoic acid ethyl ester showed considerably higher stability (with losses of 19–34%) than did the natural pigments all-E-lutein and all-E-zeaxanthin (losses of 59–69%). At all stages of storage, the xanthophyll contents of unpasteurised and previously pasteurised samples did not differ significantly, and no obvious influence of storage temperature was observed. With respect to xanthophyll content, the results suggest that there is no necessity for low-temperature storage of freeze-dried egg yolk.