Changes During Storage

Sohd ammonium nitrate occurs in five different crystalline forms (19) (Table 6) detectable by time—temperature cooling curves. Because all phase changes involve either shrinkage or expansion of the crystals, there can be a considerable effect on the physical condition of the sohd material. This is particularly tme of the 32.3°C transition point which is so close to normal storage temperature during hot weather. 

Tea Beverages. Uncoated aluminum is not compatible with tea beverages since direct contact causes discoloration and undesired flavor changes during storage. When the water contains dissolved iron, it can react with the tannin in the tea and cause darkening in the presence of air. Dissolved air in the beverage or in the headspace of the can should be... 

An important consideration prior to sample collection is transportation and storage. Samples should be treated so as to retain the integrity of the sample from the moment of collection to the time of analysis. The physico-chemical characteristics of a sediment sample change during drying, with effects on the sorption-desorption behavior of chemicals. 

It has been observed that treatment with natural antimicrobial volatiles also affected the antioxidant capacity of fruits (Ayala-Zavala and others 2005). ORAC values of control strawberries changed during storage at 7.5°C (Fig. 11.3, III). However, significant increases in antioxidant capacity values were observed in strawberries treated with methyl jasmonate, methyl jasmonate-ethanol, and ethanol. One explanation for this difference could be associated with differences on total phenol content (Ayala-Zavala and others 2005). 

Earle et al. [1.89] showed, that the RM in the product Pedvax HIB TM did not change during storage at 2-8 °C for 24 months if the stoppers were steam-sterilized, vacuum dried for 6 h and finally dried at +143 °C for 4 h. If the vials were closed with stoppers which had not been dried, the RM increased in 12 months to approx. 5.3 %. Danielson [1.90] warned against toxic components which could diffuse or migrate from the stopper to the product. A protective coating does not avoid the extraction of these substances, but Teflon coating is better than none. 

As a result of these reactions and volatilization, concentrations of nitrogen species are expected to change during sampling and sample storage. This is particularly true if precautions are not taken to limit this eventuality [29-31],... 

There have been some questions raised about the validity of results of extensive and sequential extraction methods. There is the possibility that species of an analyte may change during the extraction process. It is also possible that a species may be liberated and then reabsorbed during extraction or subsequent isolation. The same or similar question could be raised about various initial sampling and subsequent storage methodologies as described next. In spite of these questions, the BCR methodology has been widely accepted [39-41],... 

The problem of species changes during sampling and storage can be ameliorated in two ways. First, the soil component of interest can be measured in situ,... 

In this work, we adapted a method for the analysis of beer aldehydes using solid-phase microextraction (SPMF) with on-fiber derivatization. This extraction technique does not require solvents, consists of a one-step sample preparation procedure, and provides high sensitivity and reproducibility. It enabled a detailed study of aldehyde level changes during packaged beer storage. 

The properties of some of the materials suitable for HPLC are summarized in Table I. It should be borne in mind that these materials, including the occasionally used porous glasses, are amorphous xerogels whose properties vary not only from brand to brand but may also vary from batch to batch, and may additionally change during storage and treatment used for purification. ... 

Ferreres, F., Gil, M.I., and Tomas-Barberan, F.A., Anthocyanins and flavonoids from shredded red onion and changes during storage in perforated films. Food Res. Int., 29, 389, 1996. 

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