Solidification Points Introduction

Determinations of milk fat melting and solidification points are attempts to quantify the upper end of the milk fat melting point range. The result obtained from a measurement depends on the method used a melting point or a solidification point is defined by the technique and conditions of measurement, and the reported value is specific for these (Kaylegian and Lindsay 1994 Firestone, 1998). 

The clear point, also called the clear melting point, complete melting point, complete fusion point or capillary melting point, is the temperature at which a sample of fat becomes visibly completely clear, indicating the disappearance of all traces of solid fat (Rossell, 1986 Stauffer, 1996). Its measurement is specified by the American Oil Chemists Society (AOCS) Official Method Cc 1-25 (Firestone, 1998). Samples of the tempered fat contained in at least three vertical glass capillary tubes, sealed at their lower ends, are attached to a vertical mercury-in-glass thermometer such that their lower ends are level with the lower end of the thermometer s bulb. This assembly is immersed in a water bath and heated, and the 

This measurement is claimed to be more reproducible than the slip point (see below), and is the most widely accepted technique for determining melting point (Rossell, 1986 Kaylegian and Lindsay, 1994). It is the method usually used for milk fat. 

Clear points can be determined objectively by dilatometry, differential scanning calorimetry or nuclear magnetic resonance (Mertens, 1973 deMan et al., 1983). Measured values are not necessarily equivalent either to that obtained using the AOCS Cc 1 25 standard method or to each other. Dilatometry and differential scanning calorimetry are described below. 

The slip point is lower than the clear point and corresponds to a solid fat content of 4-5% (Rossell, 1986 Stauffer, 1996). The slip point of fats can be used as an indicator of relative differences in melt-in-the-mouth characteristics (Mertens, 1973). 

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The behaviour of droplets, as a whole, is a complex area of interest to researchers in a variety of fields, such as combustion, aerosol science and spray technology, to mention a few. Recently, Frohn and Roth have written about many aspects of droplet dynamics and the reader is referred to their book as a good introduction to the subject. However, from an inkjet point of view the researcher is primarily interested in the behaviour of droplets on the substrate, from the moment when the droplet lands to the droplet s end-state. In the first instance, the researcher strives to ensure that droplets land in their specified locations and remain there. Then, they try to control the droplets behaviour in order to obtain the desired morphology. The aim of this chapter is to discuss the lifetime of inkjet-produced droplets from the moment of their impact with the substrate to the moment when the final feature is obtained, which is typically by evaporation of the droplet s carrier solvent or by the solidification of said solvent. 

When material solidification is temperature-dependent (e.g., liquids near their freezing points), it is important to preheat the column and feed prior to feed introduction (see Sec. 12.6). 

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