SUMMARY Four sets of eight tomatoes were subjected to four blanching times of 30, 60, 90, and 120 set at 100°C. Two fruits in each set were also subjected to holding times of 5, 10, 15, and 20 min between the blanching and exhausting operations. Pectic substances were determined as water‐soluble, ammonium‐oxalate‐soluble, and dilute‐hydrochloric‐acid‐soluble fractions. The methoxyl content of each fraction was also determined. Firmness was determined by objective measurements. The 30‐see blanching treatment yielded the firmest tomatoes. These fruits were also characterized by the highest content of ammonium‐oxalate‐soluble pectin. The activity of pectin methylesterase was highest in treatments consisting of 30 see of blanching and a lo‐min holding time. The activity of pectin methylesterase seemed to be greatly suppressed after 90 set of blanching.

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SUMMARY Twelve sets of canned tomatoes, each set composed of three fruits harvested from the same plant and subjected to different ripening conditions, were analyzed for pectic constituents. Firmness was highly significantly correlated with total pectic constituents and with the ratio of the carhonyl and pectic content. Correlation between firmness and mineral content was also significant. These results indicate that a high content, large molecular size, and a low methoxyl content of the pectic constituents result in firmer tomatoes. From the results it appears that firmness is related to retention of the original pectic content and controlled demethylation. This induced demethylation increases the extent of ionic bonding and results in firm fruits.

The recent physiological studies of Hills (3) and Powell (9) have shown that biologically active materials are essential for spore germination. Evidence that the spore needs only a source of energy, such as glucose, has been presented by Knaysi (7). The views that only exogenous energy is stimulatory to the spore germinating processes are not fully substantiated by the work of Hills ( 4 ) and Stewart and Halvorson (12). These workers have presented good evidence that L-alanine is a factor which will initiate spore germination. Undoubtedly species specificity will enter into studies of this nature, as L-alanine has not been shown to function in all of the cases that have been studied.The following studies deal with the effects of naturally occurring materials, particularly those which can be utilized as a carbon source for energy, on the germinating processes. MATERIALS AND METHODSSpore suspensions. Spores of a strain of Bacillus thermoacidurans, F.S. 787, closely in agreement with the description of B. coagulans (Hammer), were used primarily in these studies; however, spores of Bacillus globigii and Putrefactive Anaerobe No. 3679' were included in some of the experiments in order to determine if the results were characteristic of one or more species. The cell suspensions were prepared as described in a previous report of Heiligman et aE. (2). Ultra-sonic radiation (approximately 102 watts for 5 minutes) was used in preparing the vegetative-cell-free spore suspensions. The concentration of the spores was kept constant (approximately 20,000 per ml.) so as to eliminate any effects due to this factor. Criterion of germination. As suggested by Wynne and Foster (13, 14) spores which had lost their resistance to heat were considered as having germinated. Quantitative results were based on the difference, calculated in percent, in the number of viable cells in an aliquot after a germination incubation treatment as compared to the viable cell count of a similar aliquot after it had been heated a t 100°C. for one minute. The former count represents the total count of all the viable cells, both those which had and those which had not lost their resistance to heat; the latter represents a count of the residual viable spores. The difference between these counts, then, would be the number of spores which had lost their resistance to heat as a result of the incubation germination treatment.Treatment of spores. The spores were added aseptically to sterile solutions of the materials. These suspensions were given a germination incubation a t the desired temperature and aliquots for counting were taken periodically. The germination incubation temperature, except for some preliminary studies on B. thermoacidurans, was 50°C. f o r this organism, and 37°C. for B. globigii and P.A. 3679. Since P.A. 3679 is an anaerobe a