Search results for "Process (engineering)"

1983

Solutions of poly (decyl methacrylate) in isooctane (2,2, 4-trimethylpentane) show lower critical solution temperatures (LCST) that lie well below the thermal degradation of the polymer. The corresponding exothermal theta-temperature (from the Shultz-Flory plot) amounts to 210°C. The increase in solvent quality by pressure turns out to be very pronounced (d Tc/dp ≈ +1 K/bar). With solutions of the polymer in motor oils, high temperature demixing is unlikely to occur below their boiling point. The theoretical evaluation of published experimental data for 11 different systems exhibiting LCSTs demonstrates the following: Under the equilibrium vapour pressure of the solution high temperature de…

Dispersive micro-solid phase extraction

2019

Abstract Dispersive micro-solid phase extraction (D-μSPE) has gained special attention in the sample preparation process due to its simplicity, speed and efficiency. Different dispersion approaches have been used within this technique to allow a close contact between the sorbent and the donor sample solution during the entrapping step, but also between the sorbent and the solvent in the elution step. This dispersion favors the kinetics of both sorption and elution and therefore increases the efficiency of the overall extraction procedure. This technique boasts of high versatility owing to the great variety of solids available, covering a high range of chemical functionalities. This article …

Liquid sample introduction in inductively coupled plasma atomic emission and mass spectrometry — Critical review

2014

Abstract Inductively coupled plasma optical emission spectroscopy (ICP-OES) and mass spectrometry (ICP-MS) can be considered as the most important tools in inorganic analytical chemistry. Huge progress has been made since the first analytical applications of the ICP. More stable RF generators, improved spectrometers and detection systems were designed along with the achievements gained from advanced microelectronics, leading to overall greatly improved analytical performance of such instruments. In contrast, for the vast majority of cases liquid sample introduction is still based on the pneumatic principle as described in the late 19th century. High flow pneumatic nebulizers typically deman…

HPLC-DAD-ESI-MS2analytical profile of extracts obtained from purple sweet potato after green ultrasound-assisted extraction

2016

International audience; Ultrasound pre-treatment (UAE) was applied to assist the extraction of valuable compounds (polyphenols (especially anthocyanins), and proteins) from purple sweet potato (PSP). Under optimum conditions (ultrasound time (40 min); supplementary hot extraction (80 °C) up to 120 min; pH: 2.5; ethanol concentration: 58%), the highest concentrations of polyphenols (3.877 mg/g), anthocyanins (0.293 mg/g), and proteins (0.753 mg/g) were found, with minimal specific energy consumption (8406 J/mg).Moreover, anthocyanin and non-anthocyanin polyphenols in PSP extract from optimized extraction temperature were identified using HPLC-DAD-ESI-MS2. The major identified anthocyanins we…

Understanding of the phenomena involved in the inactivation of bacterial spores by a process combining high pressure and heat treatment

2022

High Pressure Processing (HPP) is an established food processing technique for maintaining food quality while inactivating vegetative forms of pathogenic and spoilage bacteria. However, bacterial spores are very resistant to pressure, which requires the development of a strategy combining HPP with another modality (pressure cycling, heat treatment) to increase spore destruction. Currently, the combination of these processes are not implemented at an industrial scale due to the technically complex implementation and uncertain results given the diverse and contradictory literature on the level and mechanisms of spore inactivation by HP. The elucidation of spore inactivation mechanisms by pres…

Interactions between flavor compounds and food ingredients and their influence on flavor perception

2002

Interactions between flavor compounds and food ingredients are reviewed and their influence on flavor perception is discussed. Proteins are known to bind flavor compounds. For β-lactoglobulin, the most-studied example, hydrophobic interactions with volatiles are described. The effect of the medium on the conformation of the protein and its ability to bind flavor compounds is discussed. In general, the retention of volatiles by protein is much lower than that by fat. In emulsions, however, the presence of protein at the oil/water interface induces a significant effect on flavor release and flavor perception of hydrophobic flavor compounds. For starch, an extensively studied hydrocolloid, amy…

Process understanding of a wastewater batch reactor with block-wise PLS

2007

In this work a systematic methodology ‘block-wise PLS’ has been applied to thoroughly analyse data from a sequencing batch reactor (SBR) operated for biological phosphorus removal from wastewater. The aim of this study was to diagnose process variables (collected by the inexpensive and low-maintenance sensors installed in the SBR) likely related to the main key indicator of process performance: the phosphorus removal efficiency (PRE), determined off-line in the quality control laboratory. In this way, it is intended to aid the process operators in the detection of abnormal values of these critical variables which would indicate undesirable process performance, so that, they could act on the…

Using Unfold-PCA for batch-to-batch start-up process understanding and steady-state identification in a sequencing batch reactor

2007

In chemical and biochemical processes, steady-state models are widely used for process assessment, control and optimisation. In these models, parameter adjustment requires data collected under nearly steady-state conditions. Several approaches have been developed for steady-state identification (SSID) in continuous processes, but no attempt has been made to adapt them to the singularities of batch processes. The main aim of this paper is to propose an automated method based on batch-wise unfolding of the three-way batch process data followed by a principal component analysis (Unfold-PCA) in combination with the methodology of Brown and Rhinehart 2 for SSID. A second goal of this paper is to…

Utilisation of pectin coating to enhance spray-dry stability of pea protein-stabilised oil-in-water emulsions

2010

International audience; In this study, development of pea (Pisum sativum) protein stabilised dry and reconstituted emulsions is presented. Dry emulsions were prepared by spray-drying liquid emulsions in a laboratory spray-dryer. The effect of drying on the physical stability of oil-in-water emulsions containing pea protein-coated and pea protein/pectin-coated oil droplets has been studied. Oil-in-water emulsions (5 wt.% Miglyol 812 N, 0.25 wt.% pea protein, 11% maltodextrin, pH 2.4) were prepared that contained 0 (primary emulsion) or 0.2 wt.% pectin (secondary emulsion). The emulsions were then subjected to spray-drying and reconstitution (pH 2.4). The stability of the emulsions to dry pro…

Current and New Insights in the Sustainable and Green Recovery of Nutritionally Valuable Compounds from Stevia rebaudiana Bertoni.

2015

International audience; The South American plant Stevia rebaudiana Bertoni is a great source of noncaloric sweeteners (steviol glycosides), mainly concentrated in its leaves, but also has important antioxidant compounds (vitamin C, polyphenols, chlorophylls, and carotenoids) and other important macro- and micronutrients such as folic acid and all of the essential amino acids except tryptophan. Traditionally, conventional methods have been used to recover nutritionally valuable compounds from plant food matrices. However, nowadays, the need for obtaining greener, sustainable, and viable processes has led both food industries and food scientists to develop new processes in full correspondence…