Search results for "paste"
showing 10 items of 179 documents
Mathematical Model of Solid Food Pasteurization by Ohmic Heating: Influence of Process Parameters
2013
Pasteurization of a solid food undergoing ohmic heating has been analysed by means of a mathematical model, involving the simultaneous solution of Laplace’s equation, which describes the distribution of electrical potential within a food, the heat transfer equation, using a source term involving the displacement of electrical potential, the kinetics of inactivation of microorganisms likely to be contaminating the product. In the model, thermophysical and electrical properties as function of temperature are used. Previous works have shown the occurrence of heat loss from food products to the external environment during ohmic heating. The current model predicts that, when temperature gradient…
The effect of Holder pasteurization on the lipid and metabolite composition of human milk
2022
Human milk (HM) is the gold standard for newborn nutrition. When own mother's milk is not sufficiently available, pasteurized donor human milk becomes a valuable alternative. In this study we analyzed the impact of Holder pasteurization (HoP) on the metabolic and lipidomic composition of HM. Metabolomic and lipidomic profiles of twelve paired HM samples were analysed before and after HoP by liquid chromatography-mass spectrometry (MS) and gas chromatography-MS. Lipidomic analysis enabled the annotation of 786 features in HM out of which 289 were significantly altered upon pasteurization. Fatty acid analysis showed a significant decrease of 22 out of 29 detectable fatty acids. The observed c…
Pulsed electric fields as an alternative to thermal processing for preservation of nutritive and physicochemical properties of beverages: A review
2017
Fruit juices and other beverages constitute an important source of bioactive compounds, but thermal processing may reduce their contents thus decreasing natural nutritive value of foods. This has been recently led to the use of non-thermal technologies, especially pulsed electric fields (PEF) as an interesting alternative to thermal pasteurization of beverages. Reported results show that PEF is a useful for pasteurization of fruit juices that can minimize changes in physicochemical and nutritional properties with retention of higher amounts of health-related phytochemicals. This study presents an overview of the effect of PEF on the physicochemical (e.g., Brix, pH, viscosity, acidity, color…
Use of a logistic model to assess spoilage by Byssochlamys fulva in clarified apple juice
2010
Abstract The percentage P (%) of spoiled bottles (n = 40) of clarified apple juice due to Byssochlamys fulva, was modeled by using a logistic model: P = P max 1 + exp ( k ( τ − t ) ) where Pmax (%) the maximum percentage of spoiled bottles, k (h− 1) a slope parameter and τ (h) the time for P = Pmax/2. Bottles of pasteurized apple juice were inoculated with B. fulva IOC 4518 ascospores for low and high initial loads, 4.8 ± 2.3 ascospores/100 mL and 19.3 ± 4.6 ascospores/100 mL respectively and incubated at 21 °C and 30 °C. Pmax was not significantly different from 100% except for a low initial load at 21 °C. Model parameters were estimated with a good accuracy, RMSE in the range 3.89–7.50. T…
A new simple approach to evaluate pedogenic clay transformation in a Vertic Calcisol
2006
The aim of this study is to characterize the pedogenic clay minerals by using simple approach: Mixing mineralogical and geochemical findings. The fine clay fractions (< 0.1 μm) of a Vertic Cambisol profile were studied by means of X-ray diffraction (XRD), infrared spectroscopy (FTIR) and cation exchange capacity (CEC). Qualitative and quantitative mineralogical compositions of the clay mixture were determined. Moreover, chemical equilibria and thermodynamic stabilities of minerals (calcite, gypsum, kaolinite, smectites and illites) were studied using results of ionic activities obtained from total concentration of various aqueous species in water extracts from soil-saturated pastes. XRD ana…
Cream fermentation by a mixed culture of lactococci entrapped in two-layer calcium alginate gel beads
1992
This investigation was directed towards the development of a process which produces a fermented cream of greatly reduced cell number.Lactococcus lactis subsp.Lactis andLactococcus lactis subsp.lactis biovardiacetylactis were entrapped separately in normal or two-layer Ca-alginate gel beads. Pasteurized cream (31% fat content) was inoculated with free-cells and with normal or two-layer beads. When 8% of the total volume was occupied by the gel, there was 300–800 times more inoculum in this system and the fermentation time was considerably reduced (5h against 18h). When pH 5.0 was reached, the residual free-cell count was 150 and 1800 times less than for a classical inoculation method with fr…
Studies on mechanism and physico-chemical parameters at the origin of the cement setting. I. The fundamental processes involved during the cement set…
1995
Abstract The mechanical evolution and the structure of the cement paste have been analysed in relation with the chemical evolution of the system. The setting process can be described as following two fundamental steps: the coagulation of cement grains during the first minutes following the mixing, and the rigidification of the coagulated structure which arises simultaneously with the acceleration of the hydrates formation During the coagulation step, the structure formed is proved to be mechanically reversible. The rigidification of the coagulated structure is provided by the hydrates formation in the contact zone. The increase of the paste cohesion at this stage is proportional to the quan…
On the physico-chemical evolution of low-pH and CEM I cement pastes interacting with Callovo-Oxfordian pore water under its in situ CO2 partial press…
2014
International audience; Abstract Within the framework of geological repositories for radioactive waste, structural concretes must be adapted to the underground chemical conditions. CEM I cement-based materials are characterised by high pH that may produce an alkaline plume in the near-field of the repository. In order to avoid this problem, low-pH cements have been designed. This study compares the physico-chemical behaviour of a low-pH material with a CEM I cement paste, both being subjected to leaching by an aqueous solution. An original experimental setup was designed to reproduce the underground conditions using a specific CO2 regulation device. Under these conditions, the low-pH materi…
Retention of aroma compounds in starch matrices: competitions between aroma compounds toward amylose and amylopectin
2002
International audience; The retention of three aroma compounds-isoamyl acetate, ethyl hexanoate, and linalool--from starch-containing model food matrices was measured by headspace analysis, under equilibrium conditions. We studied systems containing standard or waxy corn starch with one or two aroma compounds. The three studied aroma compounds interact differently: ethyl hexanoate and linalool form complexes with amylose, and isoamyl acetate cannot. However, in systems containing one aroma compound, we observed with both starches a significant retention of the three molecules. These results indicate that amylopectin could play a role in the retention of aroma. In systems containing two arom…
Quality characteristics of horchata (a Spanish vegetable beverage) treated with pulsed electric fields during shelf-life
2005
Abstract The application of pulsed electric fields (PEF) is one of the new non-thermal technologies being studied to evaluate their potential as alternative or complementary processes to thermal pasteurization. “Horchata de chufa” (tiger nut milk or earth almond milk) is of high nutritional quality and therefore has great potential in the food market, limited by its very short shelf-life. The present work studies whether PEF can be used to obtain a quality horchata and increase its shelf-life while maintaining its organoleptic characteristics. In order to do so we determined pH, total fat, peroxide index, thiobarbituric acid-reactive substances index, formol index, and peroxidase activity i…