De Smet process

Aqueous scouring is expensive in terms of water use and effluent treatment and it can cause entanglement of delicate wool fibres. Solvent scouring offers an effective alternative but it is essential that the solvent does not enter the environment. Earlier solvent-based processes included the use of perchloroethylene in which 8-18% water had been emulsified with a surfactant. Current processes are based on hexane (de Smet process), 1,1,1-... 

The main commercial fractionation process for milk fat is the Tirtiaux process, followed by the De Smet process. There are also some proprietary variations of the dry fractionation process which enable the production of various milk fat fractions. The characteristics of the fractions obtained are affected by many factors, including the equipment design, the associated process, the initial temperature of the molten fat, the crystallization conditions (e.g., degree of initial supercooling), the rate of subsequent cooling and agitation after crystallization commences, the final temperature of fractionation and the method used to separate the fractions. 

In contrast, the de Smet process uses a similar control principle but applies it in a different way [16]. The temperature of the liquid in the crystallizer jacket is lowered stepwise in precise and precalculated steps to bring the temperature of the crystallizing fat down to the desired level within a set time period. According to de Smet, this allows the fat to be first conditioned prior to the nucle-ation step that occurs during the early part of the cooling process. This is followed by crystal growth, which continues up to the final filtration temperature, when the stearin is separated from the olein by filtration. 

The authors acknowledge the leadership of Dr. Maurits De Smet in establishing the internal processes described herein. We thank Drs. Greg Worosila, Xiande Wang and Kelly Swinney for critical review of the manuscript. 

The AMERT is an important part of the analytical method development process. The AMERT allows to verify whether the draft method performs adequately for its intended purpose and complies with the specific country requirements. The concept of performing an AMERT was introduced by Crowther et al. and has been further discussed by Jimidar and De Smet. Detailed description of the approach is presented in reference 1. 

Membrane filters have a much better separation efficiency, and oil entrainment is reduced to 40 45% (Deffense, 2000). With softer and/or less evenly sized crystals, such as the crystals that tend to be obtained in the De Smet crystallization process, membrane filters are much preferred. However, membrane filters are being used increasingly for all crystallization systems to get better separations and less oil entrainment, especially in multistep fractionation, where crystals can become more difficult to filter. An added advantage is that membrane filtration is easier to conduct under an inert gas. 

Currently, dry fractionation of anhydrous milkfat is performed by two conventional systems—Tirtiaux and De Smet (both from Belgium)—which are bulk crystallization processes. The widely used Tirtiaux dry fractionation process enables one-step or up to hve-step fractionation of anhydrous butter oil at any temperature, ranging from 50°C to 2°C (37, 110-113). The milkfat fractions thus obtained can be used as such or the fractions can be blended in various proportions for use as ingredients in various food-fat formulations. The major shortcoming inherent in this system is the long residence time (8-12 h) for nucleation and crystal growth. 

De Smet et al. introduced a continuous process combining SRNF with homogeneous catalysis. The concept was proven with two enantioselective hydrogenation catalysts, Rh-EtDUPHOS and Ru-BINAP, separated from a methanol reaction mixture by the commercial MPF-60 membrane with rejection values of 97-98%. Hydrogen played the role of reagent for the catalysis and its pressure provided the driving force for the separation [17]. 

Persons with acute or chronic stomach inflammation should use caution when taking raw or minimally processed garlic products (De Smet 1992 Felter and Lloyd 1898 Nelson et al. 2006). Persons with acid-reflux should avoid garlic due to the reported relaxing effects on the lower esophageal sphincter of aromatic compounds (Brinker 2001). 

P. Smets. A mathematico-statistical model simulating the process of medical diagnosis. PhD thesis, Universite Libre de BruxeUes, Faculty of Medicine, 1978. 

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