Further Results on Moisture Determination of Foods by Hydrogen Nuclei Magnetic Resonance.
About: This article is published in Journal of AOAC International.The article was published on 1956-05-01. It has received 4 citations till now.
Citations
More filters
TL;DR: This review summarizes the concepts of water content, water activity, and glass transition and documents their importance to quality and shelf life of confections.
Abstract: From hardening of marshmallow to graining of hard candies, moisture plays a critical role in determining the quality and shelf life of sugar-based confections. Water is important during the manufacturing of confections, is an important factor in governing texture, and is often the limiting parameter during storage that controls shelf life. Thus, an understanding of water relations in confections is critical to controlling quality. Water content, which is controlled during candy manufacturing through an understanding of boiling point elevation, is one of the most important parameters that governs the texture of candies. For example, the texture of caramel progresses from soft and runny to hard and brittle as the moisture content decreases. However, knowledge of water content by itself is insufficient to controlling stability and shelf life. Understanding water activity, or the ratio of vapor pressures, is necessary to control shelf life. A difference in water activity, either between candy and air or between two domains within the candy, is the driving force for moisture migration in confections. When the difference in water activity is large, moisture migration is rapid, although the rate of moisture migration depends on the nature of resistances to water diffusion. Barrier packaging films protect the candy from air whereas edible films inhibit moisture migration between different moisture domains within a confection. More recently, the concept of glass transition, or the polymer science approach, has supplemented water activity as a critical parameter related to candy stability. Confections with low moisture content, such as hard candy, cotton candy, and some caramels and toffees, may contain sugars in the amorphous or glassy state. As long as these products remain below their glass transition temperature, they remain stable for very long times. However, certain glassy sugars tend to be hygroscopic, rapidly picking up moisture from the air, which causes significant changes that lead to the end of shelf life. These products need to be protected from moisture uptake during storage. This review summarizes the concepts of water content, water activity, and glass transition and documents their importance to quality and shelf life of confections.
175 citations
Cites background from "Further Results on Moisture Determi..."
...With the appearance of commercial instruments, the use of NMR in the determination of water content in foods rapidly increased (Shaw et al., 1953; Shaw and Elsken, 1953, 1956)....
[...]
01 Jan 1994
TL;DR: Moisture determination is one of the most important and most widely used measurements in the processing and testing of foods as mentioned in this paper, since the amount of dry matter in a food is inversely related to the amount moisture it contains, moisture content is of direct economic importance to the processor and the consumer.
Abstract: Moisture determination is one of the most important and most widely used measurements in the processing and testing of foods. Since the amount of dry matter in a food is inversely related to the amount of moisture it contains, moisture content is of direct economic importance to the processor and the consumer. Of even greater significance, however, is the effect of moisture on the stability and quality of foods. Grain that contains too much water is subject to rapid deterioration from mold growth, heating, insect damage, and sprouting. The rate of browning of dehydrated vegetables and fruits and of oxygen absorption by egg powders increases with an increase in moisture content.
84 citations
TL;DR: In this article, the nuclear magnetic properties of hydrogen were used for the quantitative analysis of the water content of sea ice from 0° C to −40° C. The data on water content were utilized to calculate the brine volume and brine weight content of the samples.
Abstract: Nuclear magnetic properties of hydrogen are used for the quantitative analysis of the water content of sea ice from 0° C. to −40° C. The data on water content are utilized to calculate the brine volume and brine weight content of the samples. Over a range of water contents of 2% to 96% the standard deviation of the nuclear magnetic resonance data from chemical analysis data is ±0.6%, An estimate of water content in a sample of sea ice at −70° C. is given, and the value of nuclear magnetic resonance measurements for field studies is discussed.
29 citations
TL;DR: Nuclear physics, physical chemistry, organic chemistry, and in the latest years, biochemistry and biology have begun to make extensive use of the nuclear magnetic resonance techniques.
Abstract: There are only a few methods available for examination of the physicochemical properties of living and relatively intact cells. One such method is nuclear magnetic resonance. This method is a form of spectroscopy using electromagnetic radiation of very long wave lengths (low frequency), which implies that the energy supplied to the biological sample is far beyond any level of damage to the cells subjected to investigation. The first successful attempts to observe nuclear magnetic resonance in bulk matter were made by Bloch et al. (1946) and Purcell et al. (1946). Nuclear physics, physical chemistry, organic chemistry, and in the latest years, biochemistry and biology have begun to make extensive use of the nuclear magnetic resonance techniques.
17 citations