Crackers moisture content

A better estimate would be obtained by dividing the time up into shorter intervals, and averaging Ap across each of those shorter intervals, instead of over the whole shelf life. For example, we could use two intervals, 8% to 22.9% RFI and 22.9% to 43%, giving an average RFIj as 15.45% RFI and 33.0% RFI in the two intervals. The cracker moisture content at 22.9% RFI is read from the graph as 3.9%. Then the calculation for the two steps is as follows ... 

A cracker package is 1.2 mil PP with a WVTR of 2.0 g mil/100 in d measured at 95°F, 90% RH. The package area is 100 in. Mass of the crackers is 100 g. Initial moisture content is 2%, and the critical moisture content (above which the crackers are too soggy so have reached the end of their sheif iife) is 5.5%. Storage conditions are 70°F, 70% RH. The isotherm is noniinear over the range in question, as shown in Fig. 14.15. Calculate the shelf life of the crackers. 

Typical equilibrium moisture contents of some food materials at approximately 298 K (2j C) (/) macaroni, (2) flow, (J) bread, (4) crackers, (5) egg albundn. [Curoe (5) from ref (El). Curves (/) to (4) from National Research Council, International Critical Tables, Vol. ll. New York McGraw-Hill Book Company, 1929. Reproduced with permission of the N ational Academy of Sciences. ... 

There are several thousand NIR moisture sensors installed in different industries, but due to the competitive and proprietary nature of the processes, there have been very few reports in the literature about successful, specific applications. From among the reported applications, a Moisture Register NIR analyzer was used to look at the moisture content of crackers moving at a speed of 100 ft/min [59]. Other early examples were paper moving at 50 ft/min web speed and phosphate ore-drying process monitoring [60]. A comparative study of different noncontact instmments was reported to measure cake moisture in wastewater treatment [61]. 

To date, only microwave hot-air dryers used principally in flnish drying processes to level-off the moisture content in pasta, crackers or chips, and microwave vacuum dryers custom-made to specific product requirements, are available commercially (Ratti, 2008). Good microwave-assisted drying equipment should have a uniform distribution of the microwave field, provide a movement of the material to be dried, keep the microwave field strength in the drying chamber lower than the dielectric breakdovm strength, and possess an economic dehumidification system. 

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