The vacuum seals were made in clamp-top fruit jars by means of a home pressure cooker. Filled jars, with covers partially clamped, were placed in the cooker. The cooker cover was lubricated at the sealing surface and screwed down tightly. The pressure gauge in the top of the cooker was replaced with a vacuum gauge. The needle valve was removed. An aspirator was attached to the water faucet and connected to the needle valve opening by means of a vacuum hose. After the desired vacuum had been pulled on the cooker, the vacuum hose was removed from the needle valve fitting thus permitting air to rush back into the cooker. The sudden change in pressure automatically sealed the jars.
+Presentation of Data+
Preliminary studies were made to determine the effect of temperature and time of drying on moisture content, color, and toasting of kernels. Results of these studies are given in Table I.
TABLE I.—Effect of Temperature and Time of Drying on Moisture Content,
Color, and Toasting of Pecan Kernels.
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Oven Time in Moisture Change
temperature oven in in Degree of
kernels color[25] toasting
Minutes Per cent
0 3.7 0.0 0
20 2.6 0.5 0
30 1.4 1 1
37 1.2 2 2
225°F 44 1.0 3 4
51 0.5 6 8
58 0.3 8 10
65 0.2 8 10
72 0.1 9 10
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10 3.2
20 3.1
203°F 30 2.9
41 2.4
50 2.2
60 1.9
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[Footnote 25: The numbers 0 to 10 indicate varying amounts of change in color or degree of toasting: 0 represents normal color and/or no toasting. 10 represents considerable intensification of color and/or development of typical flavor of toasted kernels.]
The first series of the processing and storage tests was started in December, 1939. The treatments together with results are given in Table II. The different samples were dried in an electric oven at 225°F to moisture contents ranging from 0.1 to 3.4 per cent. They were sealed in glass jars, both with and without vacuum, and stored in a dark room at ordinary temperatures. Those dried to 2.9 per cent moisture or less were still good after 2 years in storage, whereas those with higher moisture content were rancid after one year in storage. Samples dried to approximately 2 per cent moisture were still good September 1, 1948, which was almost 9 years after processing and storing. The color was preserved somewhat better by vacuum sealing. However, the quality of air-sealed samples was practically as good as those that were vacuum sealed. These tests did not show how long kernels might have been kept by drying and storing in unsealed containers.
Table II.—The Effect of Different Amounts of Drying and Different Methods of Sealing on the Storage Qualities of Pecan Kernels (Tests made at Auburn, beginning December, 1939.)
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Per cent
No. min. moisture
Methods of Sample in oven in dry
sealing [28] No. 225°F kernels