Volatile Flavor Components from Green Peas (Pisum Sativum).

SUMMARY— The volatile alcohols of unblanched frozen green peas were separated from the total volatiles by chromatography on silica gel at 0°C and examined by combined gas chromatography-mass spectrometry and where possible by infrared spectroscopy. Thirteen saturated and nine unsaturated alcohols were positively identified: methanol, ethanol, propan-l-01, butan-1-01, butan-2-01, 2-methylpropan-l-01, pen-tan-l-01, pentan-3-01, P-methylbutan-1-01, 3-methylbutan-l-01, hexan-l-01, heptan-l-01, octan-l-01, pent-l-en-3-01, cis and trens pent-2-en-l-01, cis and trans hex-3-en-l-01, trans hept-2-en-l-01, trans act-2-en-l-01, act-1-en-3-01 and cis non-3-en-l-01. Several other alcohols were also present and, of these, trans hex-2-en-l-01, cis and trans hept-3-en-l-01 and nonan-l-01 were tentatively identified.
The interconnecting system between gas chromatograph and mass spectrometer permitted the collection, for IR analysis, of material from the identical gas chromatographic peak on which the mass spectrum was obtained.     

Structural Interpretation of Immiscibility in Oxide Systems: I, Analysis and Calculation of Immiscibility

Crystal chemistry principles are applied to the quantitative interpretation of immiscibility in nineteen binary and eight ternary glass systems. Using ionic radii and one of two coordination types, two methods are given for the calculation of immiscibility in binary systems. The additive density method gives agreement with experimental results in both the borate and silicate systems to within about 5 mole %. The oxygen-volume method agrees, in general, to within 2 mole %. The maximum extent of immiscibility in ternary borosilicate systems can also be calculated. The importance of the electrostatic bond strength, defined as the valence divided by the coordination number, is discussed in relation to shape of liquidus curve, cation coordination type, and charge distribution on the network-former tetrahedra. Implications of the analysis to the structure of glass are presented.     

Papaya Polygalacturonase and its Role in Thermally Injured Ripening Fruit

The polygalacturonase (E.C. 3.2.1.15) (PGase) activity in papayas increased with fruit ripeness. PGase activity was highest in the placenta with the activity decreasing outwardly from the placenta to the exocarp. Extended hot water treatments (46°C for 65 and 90 min) caused delayed softening of the fruit tissue which was correlated to a decrease in PGase activity. The decrease in PGase activity after the heat treatments was more severe in the riper fruits (quarter and half ripe) than the less ripe fruits (colorbreak stage).     

Respiratory Enzyme Activity in Low Temperature Sweetening of Susceptible and Resistant Potatoes

During storage at 4°C and 12°C, a potato cultivar susceptible to chill-sweetening (Norchip) accumulated significantly (P≤0.05) higher levels of sucrose, fructose and glucose than a potato selection resistant to chill-sweetening (ND 860-2). ND 860-2 tubers exhibited a significantly (P≤0.05) higher respiration rate throughout storage, reflected in higher activities of phosphofructokinase (PFK), glucose-6-phos-phate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH). Storage significantly (P≤0.05) reduced respiration rate for both cultivars. G6PDH showed no significant (P>0.05) difference in specific activity or V_max between 4°C and 12°C for either cultivar. However, Km decreased at 4°C for both cultivars, possibly due to build up of substrate.     

SURFACE ULTRASTRUCTURE AND TENSILE PROPERTIES OF CATHEPSIN AND COLLAGENASE TREATED MUSCLE FIBERS

Beef and rabbit psoas muscle fibers were soaked in a crude muscle cathepsin preparation, collagenase or 2% KCl. Tensile properties (breaking strength and break elongation) and surface ultrastructure were monitored. Cathepsins considerably accelerated decreases in tensile properties found in an un-soaked control while KC1 produced significant but less extreme effects. Collagenase showed similar results for breaking strength but break elongation was only slightly influenced. Surface ultrastructure revealed that KC1 caused a variable loss of structure including collapse and disappearance of striations, swelling and some transverse fiber breakage. Cathepsins speeded and expanded this damage producing multiple breakage with extensive disruption in some cases. These effects are similar to those observed in naturally aged meat and occur at the same temperature and pH. Collagenase treatment, however, initially brought about a shredding and dissolution of collagen fibers followed by disintegration of the sarcolemma and exposure of relatively undamaged myofibrils.     

Effect of Low Temperature Storage on Sugar Concentrations and Chip Color of Certain Processing Potato Cultivars and Selections

Two potato cultivars (Kennebec and Simcoe) and one selection (ND 860–2) were stored for 3 months at 4°, 9° and 11°C. ND 860–2 had the lowest sugar content at all storage temperatures, produced the lightest colored chips and was the only sample which gave acceptable colored chips directly from 4°C storage. In another study, three potato cultivars (Norchip, Simcoe and Onaway) and one selection (ND 860–2) were evaluated for sugar content and chip color during growth and harvest, two weeks prior and two weeks after foliar senescence, and stored under various time —- temperature regimes and upon reconditioning. ND 860–2 generally had the lowest levels of fructose, glucose and sucrose and Onaway had the highest. Storage at 5°C resulted in increases in the three sugars for all tubers, sucrose showing the most notable increase. ND 860–2 was the only sample to consistently produce acceptable colored chips directly from 5°C.     

SEED COAT EFFECTS IN COOKED RECONSTITUTED BEAN TEXTURE

The contribution of seed coat to cooked reconstituted bean texture was assessed by measuring sensory and instrumental parameters of beans with and without coats and also seed coats alone. Experiments using white beans stored for one year under tropical conditions to induce the hard-to-cook (HTC) defect or temperate conditions both resulted in reductions in the order of 50% in puncture force and sensory properties of beans when the seed coat had been removed. HTC bean texture was influenced less by absence of the seed coat than texture of soft beans. Seed coats softened during cooking but those from HTC beans softened less than those from soft beans. It is possible that seed coats harden during tropical storage by a lignification-type mechanism. Beans with harder seed coats absorbed less water during soaking which may contribute further to bean hardness.