Composition of volatile compounds in bovine milk heat treated by instant infusion pasteurisation and their correlation to sensory analysis

Volatile compounds in skim milk and nonstandardised milk subjected to instant infusion pasteurisation at 80°C, 100°C and 120°C were compared with raw milk, high temperature short time pasteurised milk and milk pasteurised at 85°C/30 s. The composition of volatile compounds differed between infusion pasteurisation treated samples and the reference pasteurisations. The sensory properties of skim milk subjected to instant infusion pasteurisation were described by negative attributes, such as cardboard sour and plastic flavours, which are not associated normally with fresh milk. Partial least squares modelling showed good correlation between the volatile compounds and the sensory properties, indicating the predictive and possible causal importance of the volatile compounds for the sensory characteristics.     

Impact of processing steps on the composition of volatile compounds in cheese powders

Changes in the composition of volatile compounds during processing of cheese powders, made from Emmental and Danbo cheese were analysed by dynamic headspace gas chromatography–mass spectrometry. Samples comprised cheese, melted cheese slurry, the slurry heat treated using three different time and temperature combinations, and the spray‐dried cheese powder. About 100 volatile compounds were identified. During melting of the cheese the level of some volatile compounds increased significantly; heat treatment mainly leads to a loss of compounds and spray drying leads to a substantial reduction of volatile compounds, with the exception of a range of aldehydes that increased. The final cheese powders could, however, be distinguished according to cheese type.     

DRYING KINETICS FOR MURICI (BYRSONIMA CRASSIFOLIA) FRUIT

The objectives of this work were to study and to model the drying kinetics of murici (Byrsonima crassifolia) fruit, with and without peel, using the diffusional model (Fick's second law) adapted to a cubic geometry. The drying data were obtained using a convective vertical tray drier at three different temperatures (50, 60 and 70C). The kinetics study showed that increasing air temperature favored the decrease of drying time. The Fick model can be used to describe successfully the murici drying process.     

THE REMOVAL OF β-LACTOGLOBULIN FROM STAINLESS STEEL SURFACES AT HIGH AND LOW TEMPERATURE AS INFLUENCED BY THE TYPE AND CONCENTRATION OF CLEANING AGENT

In the food industry, severe fouling of equipment surfaces is common and frequent cleaning is necessary. The aim of this work was to contribute to an understanding of the cleaning process. The adsorption of β-lactoglobulin (β-LG) onto stainless steel surfaces and its removal by detergent were followed at 24 and 82C using in situ ellipsometry. Soil removal using different concentrations of sodium hydroxide was studied. Furthermore, NaOH was combined with the anionic surfactant sodium dodecyl sulphate (SDS). Increasing the NaOH concentration resulted in an enhanced cleaning rate and better cleanability. When the concentration was increased to 0.8 mg/mL, the cleaning process could no longer be monitored by ellipsometry. Combining SDS with NaOH resulted in improved cleaning compared to if using the individual components. Adsorption and removal of β-LG at high temperature led in all cases to decreased cleanability compared to the results obtained at room temperature.