Review - Food

Abstract

HIS reyieiy covers some 2 years that have passed since the previous one was completed (190), and includes papers rapid when final drying in a water or vacuum oven is preceded by heating in a water bath for 1 hour.An apparatus for determining moisture in grains and flour by use of electric conductivity has been patented in Japan (136). Application of the old toy used to predict the weather (not too published during this time. MOISTUREKesearrh on moisture determination by nuclear magnetic resonance has been continued, and a recent paper (263) reports that this method has shown promise for rapid routine use. One important advantage is that it does not require essential modification of the test specimen. The method is effective in moisture ranges from a fevi per cent to as high as 100%.Moisture determinations with the Karl Fischer reagent have been critically evamined and discussed in three papers (57, 152, 281). Efforts have been made to substitute other reagents for methanol, and formamide has been found to be more versatile than methanol for moisture in such foods as beans, cahe mix, dried whole eggs, egg noodles, rolled oats, rice, and wheat ( 1 7 7 ) . Another modification makes use of a solution of bromine and sulfur dioxide in anhydrous chloroform instead of methanol ( 1 4 ) . I n the determination of moisture in honey using different methods, the Karl Fischer technique gave the highest values. while the refractive index method of the A40AC gave the lowest value ( 1 ) A method has been proposed (290) for estimating moisture in sugar-containing products, such as honey, jams, and fruit juices, based on the property of absolute alcohol to form an azeotropic mivture TTith n-ater of the sample, and upon the use of a special colloidal silicate which dries easilv. I n the case of dry sugar, it was found ( 9 4 ) that drying the sugar a t 130' C. for 45 to 60 minutes gave results identical with those obtained by drying a t lower temperatures for 4 hours or longer. 1Ioisture determinations in cheese have been carried out by placing the cheese between two previously weighed sheets of unlacquered aluminum 15 x 19 X 0.0016 em. (268). This is somewhat similar to the glac;s rod technique of the AOAC (@), in which the cheese is smeared on a glass rod. This method results in an improvement in the precision of the vacuum oven method for determination of moisture in both process cheese and cheese food, in that there is less burning of the sample. It has been reported (163) that loss of moisture in cheese is most accurately) has been utilized to measure moisture in milled products (230). Dried filter paper is impregnated with cobalt chloride, which changes from blue to red when exposed to moisture. An infrared method has been proposed for measuring moisture in starch ($94). A 10-gram sample is placed in an aluminum dish and irradiated with a 250-watt infrared lamp a t 10 em. After 15 minutes the sample is cooled in a desiccator and weighed.Several methods have been suggested for determining moisture in fats and oils. A procedure...