No abstract

No abstract

SUMMARY The more volatile components of the stale flavor fraction of sterilized concentrated milk (SCM) were studied by a nitrogen‐purge on‐column trapping technique. Higher‐boiling components were isolated by solvent extraction of the fat from lyophilized SCM, followed by low‐pressure reduced‐temperature steam distillation of the extracted fat. Components in the resulting flavor extract were identified by gas chromatography and mass spectrometry. The following compounds were identified in the extract from stale SCM: 2‐heptanone, 2‐nonanone, 2‐tridecanone, benzaldehyde, acetophenone, naphthalene, a dichlorobenzene, δ decalactone, benzothiazole and o‐aminoacetophenone. Of these compounds, only the dichlorobenzene and 2‐heptanone were identified in the extract from the control SCM.

SUMMARY– Infrared spectra of various fats and oils were determined. Ratios of absorbance at 3.3μ (olefinic C—H stretching band) to absorbance of other characteristic triglyceride absorption bands were calculated. Relationships between these ratios and unsaturation, as estimated by iodine value, were determined. Analyses of 25 fats and oils showed that the ratio of absorbance at 3.3μ to absorbance at 3.5μ (aliphatic C—H stretching band) and iodine value were linearly related and exhibited a correlation coefficient of 0.98. Estimation of degree of unsaturation of 19 additional fats and oils revealed an average deviation of ± 0.97 iodine value units or ± 1.12% between measured values and values calculated from infrared absorption patterns.

Irradiation pasteurization of flour and bread at 50,000 rads markedly reduced their microflora. Irradiation pasteurization of bread in combination with the irradiated flour extended the period of freedom or low incidence of mold growth when stored at 21–25°C improving the use of fresh bread for flights having several weeks duration. The irradiation process reduced the presence of the mold genera Aspergillus and Penicillium, which suggests an advantage when considering potential toxic metabolites that may result from mold growth. Chemical measurements, involving TBA value, gas chromatography of bread volatiles, and infrared scanning of the bread lipids, did not show any major influences due to the irradiation process. Irradiated white bread samples after short term storage contained a new carbonyl group identified in the infrared scan that was not noted in the control white bread. This same compound, tentatively identified as propionaldehyde, appeared after 12 wk in non‐irradiated white bread. Panel evaluations were unable to distinguish aroma, appearance, flavor, texture or freshness differences attributable to the irradiation process used in this study. Within the type of bread specified by NASA, no general detrimental quality changes were observed due to the irradiation treatments used. Overall the results support the application of low dose irradiation in the extension of mold‐free fresh bread for space flights.