ALBERT

Notes: SYNOPSIS. A comparison of the effects upon trypsin-dispersed chick liver cell cultures of a virulent (Jones' Barn) and a non-pathogenic (Lahore) strain of Trichomonas gallinae revealed significant differences in behavior of the parasites in cell cultures and in the response of such cultures. The virulent strain multiplies faster in nutrient medium in the presence of cell cultures; stimulates great activity of the macrophages; is not handled effectively by these phagocytes in which it can multiply causing their ultimate destruction; is found significantly more often within the cytoplasm of the liver epithelial and fibroblast-like cells; causes very much more profound degenerative changes in all the cells, both invaded and non-invaded; and suppresses effectively the division rate of the fibroblast-like cells. On the other hand, the nonpathogenic strain multiplies at a lower rate in the presence of cell cultures; stimulates less activity of the macrophages; is handled readily by these phagocytes in which it multiplies only very rarely, if ever; is found seldom within the liver epithelial and fibroblast-like cells; causes far less degeneration of all the cell culture elements; and suppresses significantly less the dlvision rate of the fibroblast-like cells.At the end of a 20–24 hour period typically only a few living cells are left in cultures exposed even to attenuated isolates of the virulent strain, whereas those inoculated with the mild one do not show much degeneration even after 28 hours. The effects upon the cell cultures of cell-free filtrates of actively growing trichomonad cultures are relatively minor, but the changes caused by the filtrates of cultures of Jones' Barn strain appear to be more extensive than those caused by similar filtrates of Lahore strain.

Notes: The formation of volatile bases and volatile acids during heat processing of albacore tuna loin sections was studied, using a closed system swept with nitrogen gas. The cell containing the tuna was heated gradually to 100°C, and the volatile acids and bases were trapped in standardized solutions. During the first 80 min of heating, at precooking temperatures, volatile acid evolved exceeded by threefold the slight amounts of volatile base (less than 0.5 mcq per 1000 g). Later during the heating cycle equal amounts of volatile acids and bases were formed.The ratio of sulfur to iron responded directly to the initial vacuum present in canned tuna. At high vacuum the ratio was 0.575. Sulfur was absent from the black deposits when the cans were sealed without evacuation, even when high levels of cystine were added. In commercially packed shrimp the sulfur to iron ratio was 0.322, which is consistent with a deposit of mixed oxides of iron, combined with ferrous sulfide. Addition of acetic acid (a volatile acid) at 10 mM per can suppressed the formation of black deposits at all closing vacuums in a model system containing added cysteine, while the addition of ammonium hydroxide (volatile base) or no addition resulted in the formation of black deposits at 26 inches Hg of closing vacuum.

Notes: The kinetics of chlorophyll degradation in spinach purée were studied over the temperature range 260—300°F, using thermal-death-time tubes heated in a constant-temperature oil bath. Pigments were separated by column chromatography, and their concentrations determined spectrophotometrically. A semilogarithmic (first-order) plot of the residual pigment vs. time was used to illustrate the thermal degradation rate (TDR). Although the major portions of the TDR curves were apparently linear, several abnormalities were observed during the initial test intervals. Regression coefficients were computed for the linear portions and used to compute the various thermo-dynamic functions characteristic of the degradation reactions. The following values respectively represent the average determinations for chlorophylls a and b. The TDR constant k, (2.3/D, D, D being decimal reduction time in sec), 1.1 × 10−2 and 0.52 × 10−2 sec−1; the temperature coefficient Q10 (log−1 18/z, z being °F affecting 10-fold change in k, or D), 1.58 and 1.26; the activation energy E, 143 and 35 Kcal mole−1; the enthalpy H, 142 and 34 Kcal mole−1; the free energy & Delta;F, 29 and 32 Kcal mole−1; and the entropy & Delta;S, 268 and 5 cal deg−1 mole−1.

Notes: Efforts were continued in an attempt to assess quantitatively the behavior of certain cellular components while the spores were being exposed to moist heat, and to correlate such behavior with the thermal death reaction.Spores of Bacillus subtilis were preheated over prolonged intervals in an attempt to induce the release of cellular dipicolinic acid (DPA) without exercising serious loss of viability, and then to evaluate the subsequent effect of DPA release upon the thermal death rate of the preheated spores. At 45°C in 2.5mM PO4 buffer at pH 7, the net DPA released amounted only to 1.6 and 2.7% at the end of 20 and 30 hr. The treated spores exhibited no loss in viability and when heated at 98.5°C in 25mM PO4 buffer at pH 7, exhibited no differenee in their thermal death rates. Prolonging the heat treatment up to 9 days did not materially change the final results. To induce faster and greater DPA release, the above experiment was repeated at 80 and 90°C. At 80°C the net DPA released was 3.6 and 4.1% at the end of 3 and 8.5 hr, without loss in viability. However, the treated spores exhibited some reduction in their thermoresistance at 98.5°C. At 90°C greater amounts of DPA were released, but were associated with substantial loss in viability, and the surviving spores exhibited marked reduction in their thermoresistance at 98.5°C. These observations suggest the existence of DPA in more than one structural form; free or loosely bound to the spore structure and easily exuded upon mild heating or even standing under refrigeration; and a second more strongly bound form which required severe heating for its release. It is this latter form which might be associated with the mechanism of thermoresistance. Along with DPA, following the same pattern but at much higher rates, ninhydrin-positive material was exuded during sublethal heating at 80, 85, and 90°C. It was suggested that such material might be of similar nature to that exuded during germination of Bacillus species as described by Powell (1957).Spore suspensions of Bacillus coagulans (thermoacidurans) of varied thermostability were heated in 25mM phosphate buffer at pH 7, at 95°C and both the rate of death and DPA release were established. Results showed a difference in kinetics between the two reactions. Death progressed at higher rates than DPA release. Higher rates of death were associated with higher rates of DPA release. Spores of same strain were heated in both water and 10mM glyeylglycine, a death accelerating agent, at 100°C, sampled at intervals and analyzed for survival, dry weight, calcium, manganese, magnesium and DPA. Results showed the death of spores and their concurrent exudation of DPA and divalent cations were both markedly accelerated in the presence of glycylglyeine. The 25-min survival and exudate levels in glycylglyeine were near equivalent to those at the 65-min levels in water.The kinetics of death and the concurrent release of DPA and calcium were further assessed in more detail in 5mM phosphate buffer at pH 7 at 96 and 99°C using spores of B. coagulans (thermoacidurans). Death again progressed at a higher rate than that of either DPA or calcium release. Based on the molar ratio of Ca/DPA released in the supernataut, the initial ratio was always greater than 1, then rapidly dropped. and eventually plateaued at a value of less than 1. Similar patterns of death and calcium and DPA release were obtained for B. cereus when heated at 86°C.All of the above observations demonstrate the association of the thermal death reaction with the exudation of ninhydrin-positive material, DPA and divalent cations into the heating menstruum. The exact relationship between such cellular components and the spore mechanism of thermoresistance remains inconclusive.

Notes: Four grape juices differing in amount of added citric acid were examined by paired comparison by 72 tasters. Some judges preferred sweet and some preferred acid juices, causing pronounced and progressive changes in the frequency distributions of the preference ratings. The correlation coefficient between variances and acid differences was 0.98. The direction and degree of preference was much more consistent for larger differences in acid. Mathematical models developed by other authors for analysis of paired comparison data are of doubtful validity or awkward in application to the present data.

Notes: The thermal destruction rates of Streptococcus faecalis, ATCC 7080, were determined in a selected group of meat and fish precooked frozen products. Data on heat transfer through these products in a hot air household electric oven, were also obtained. Accordingly, the theoretical thermal treatments required to render such products commercially sterile were computed following the procedure of the General method of process calculation for canned foods with some modification. Inoculated product tests were also made to confirm the adequacy of the computed thermal treatments.It is concluded that the procedure adopted for establishing the thermal treatment was accurate and proved feasible for this type of product. Based on the thermal resistance of our test strain, the heat treatments recommended on the commercial packages seem to be adequate, provided the heating and cooling procedures are similar to those followed in the present experiments. In the case of one product out of the five tested, however, the minimum recommended heating period fell short of the computed thermal requirement for that product.

Notes: Volatile constituents of fresh butter were separated from fat and other components of high molecular weight by vacuum steam distillation. The carbonyl compounds in the aqueous distillate were converted to their 2, 4-dinitro-phenylhydrazones. Separation of these by column and paper chromatography gave the derivatives of formaldehyde, acetaldehyde, isobutyraldehyde, isovaler-aldehyde, n-hexanal, n-nonanal, phenylacetaldehyde, acetone, 2-heptanone, 2-nonanone, diacetyl and (-)-acetoin, all identified by comparison with authentic samples. Possible biosyntheses of these flavor constituents are discussed.