SO2 Treatments Research Articles

Carbon dioxide-enriched atmospheres during cold storage limit losses from Botrytis but accelerate rachis browning of ‘Redglobe’ table grapes

We evaluated a range of CO2 and O2 concentrations as a potential substitute to SO2 treatments for controlling decay development on ‘Redglobe’ table grape during storage. During the 1998 season, early (14% soluble solids concentration, SSC) and late harvested (17% SSC) ‘Redglobe’ grapes were stored in 16 controlled atmospheres of 5, 10, 15, 20, and 25 kPa CO2 combined with 3, 6, and 12 kPa O2. During the 1999 season, 10 or 15 kPa CO2 combined with 3, 6, and 12 kPa O2 were tested in comparison with air stored grapes as control. In the 2000 season, late harvested ‘Redglobe’ grapes were kept in 12 kPa CO2+6 kPa O2 in comparison with standard commercial storage practices of SO2 fumigation. None of the atmospheres tested for up to 12 weeks at 0 °C influenced SSC, titratable acidity (TA), SSC:TA, or berry shatter and browning. Rachis browning was accelerated and trained judges perceived ‘off-flavor’ in grapes exposed to CO2 levels above 10 and 15 kPa for early and late harvested ‘Redglobe’ grapes, respectively. Atmospheres including above 10 kPa CO2 controlled decay incidence and spread among berries (nesting) independent of O2 concentrations during storage at 1 °C for up to 8 weeks and after 3 days at 20 °C, simulating a retail display period. Based on these data, a combination of 10 kPa CO2 with 3, 6 or 12 kPa O2 is suggested for up to 12 weeks storage for late harvested ‘Redglobe’ grapes. An atmosphere of 10 kPa CO2+6 kPa O2 is suggested for early harvested ‘Redglobe’ grapes, but not to exceed 4 weeks.

The kinetics and mechanism of SO2oxidation by O3on mineral dust

The oxidation of SO2 by O3 on mineral dust was studied using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Formation of sulfate was observed on the surface. A two-step mechanism that involves physisorbed SO2 followed by oxidation is presented. The formation rate was determined to be first order with respect to SO2 and zero order in O3. The reactive uptake coefficient, γ, was determined from the infrared absorbance, that was calibrated by ion chromatography, and from the geometric or the BET surface area. γSO2 was independent of the SO2 concentration and was determined to be in the order of 10−3 using the geometric surface area, or 10−7 using the BET surface area for [SO2] = 2.2 × 1012 to 2.0 × 1013 and [O3] = 5.6 × 1012 (in units of molecule cm−3). γO3 depended linearly on the O3 concentration and varied from 10−2 to 10−4 using the geometric area or 10−6 to 10−8 using the BET area for [O3] = 1.9 × 1012 to 5.5 × 1013 and [SO2] = 5.4 × 1012 (in units of molecule cm−3). In all experiments surface saturation was observed with an amount of 2 × 1019 sulfate ions g−1 on the mineral dust sample. In the presence of water vapor regeneration of active sites was observed. After several exposures to water vapor corresponding to 80% relative humidity and successive SO2 and O3 treatments the amount of formed sulfate covering the surface was increased by 47% compared to the dry experiments.

EFFECT OF STORAGE CONDITIONS, PACKAGING MATERIAL AND METABISULPHITE TREATMENT ON THE COLOR OF DEHYDRATED GREEN BELL PEPPERS (CAPSICUM ANNUUML.)

ABSTRACTGreen bell pepper dices were dipped in two metabisulphite solutions, 2400 and 3600 mg. kg‐1, respectively, and dehydrated. The dehydrated peppers were sealed in laminated pouches of different oxygen and moisture transmission rates, and stored in the dark at 0, 10 and 20C for 12 weeks. Color was evaluated by objective color measurement and a sensory panel during storage. The different packaging materials did not significantly influence color retention, while the SO2treatments showed only limited differences in their effect, but storage temperatures significantly affected visual and objective color. The best correlation between visual color evaluation and the objective color measurements, was obtained for the a* (greenness) measurements. Panelists could discriminate between samples stored at 0 and 10C in contrast to a* measurements which did not differ significantly. Calculated hue angles exhibited the highest discriminatory ability of any of the objective color parameters.

Loading beans with sublethal levels of copper enhances conditioning to oxidative stress

The relationship between Cu2+-overloading and oxidative stress in plant cells was studied. The involvement of Cu2+ in the reduction of superoxide O2− and hydrogen peroxide (H2O2) to hydroxyl radical (OH.), suggest that excess Cu in plants leads to oxidative stress. Cu excess was induced in Phaseolus vulgaris (cv. Pinto) plants by soaking the roots in a 1 mmol/L Cu(NO3)2 solution for 24 hours. As a result, Cu content in bean leaves increased from 12 to 23 mg Cu kg−1 DW. Indications for oxidative stress response were detected by monitoring changes in the activities and contents of some components of the antioxidative mechanism. The Cu treatment resulted in doubled activity of ascorbate peroxidase (APX, EC 1.11.1.11) and catalase (EC 1.11.1.6). Excess of copper inhibited glutathione reductase (GR, EC 1.6.4.2) to 60 % of control activity. No differences were found in CuZn-SOD (SOD, EC 1.15.11) and Mn-SOD activity, and glutathione and ascorbate content. Copper overloading affected also, primary reactions of photosynthesis and electron transport as probed by the photochemical energy storage in far-red light. Cu treatment of bean plants resulted in enhanced conditioning to successive methyl viologen and SO2 treatments as compared to non-treated control.

Studies of the Adsorption of SO2, H2 and O2 on a Cr2O3 Surface by an Electrical Conductivity Technique

Electrical conductivity measurements have been used to detect extremely small changes in the oxygen content of oxide semiconductors in contact with reducing or oxidizing gases. In continuation of previous studies, the oxygen loss of chromium oxide in H2 and SO2 flows, as well as the oxygen gain in an oxygen atmosphere, were studied. In SO2, the conductivity dropped instantaneously to minimum values due to its adsorption on adsorbed oxygen sites. The treatment of Cr2O3 in SO2 led to the elimination of chemisorbed oxygen and the covering of the surface with polymeric SO2. In contrast, in an H2 flow, the conductivity of Cr2O3 initially exhibited an induction period during which the value was constant. At the end of the induction period, the conductivity increased rapidly to a maximum value and then dropped sharply to a minimum. The induction period may be regarded as the time necessary to create an oxygen vacancy, the activation energy for such a process being 21.1 kJ/mol. A hydrogen molecule is then adsorbed on to the oxygen vacancy possibly as a hydride ion, and leading to the initial increase in the conductivity. The hydride ion then migrated to a chemisorbed oxygen site, where it formed a surface hydroxy group and caused a consequent decrease in the electrical conductivity. The surface then dehydroxylated due to the interaction of surface hydroxy groups with gaseous hydrogen, leaving coordinatively unsaturated surface chromium ions behind. In an oxygen flow at 400°C and above, either SO2 or H2 treatments led to a sharp increase in conductivity due to oxygen adsorption. In contrast, at temperatures less than 350°C, oxygen adsorption was retarded after an SO2 flow, possibly due to the strong adsorption of a polymeric film of SO2. Correspondingly, after H2 treatments, oxygen was adsorbed instantaneously at temperatures as low as 200°C, presumably because of the weak sorption of H2 on the surface chromium ions. After discontinuing the hydrogen flow, further oxygenation caused a subsequent decrease in the conductivity, possibly due to surface hydroxylation. Hydrogen trapped in the bulk of the Cr2O3 could spill over the surface and cause such a hydroxylation process.

Fumigation of Table Grapes with Acetic Acid to Prevent Postharvest Decay

Acetic acid (AA) fumigation controlled decay of Summerland Selection 494 and Selection 651 table grapes in repeated trials over a 3-year period when grapes were fumigated with 0.27% vol/vol AA and stored for 6 weeks at 2 or 5 degrees C. Fumigation of Selection 651 at approximately 2-week intervals with AA or SO2 controlled both Botrytis and Penicillium decay and reduced berry shatter equally in two separate years. No significant difference occurred between SO2 and AA treatments in yield components (cluster and berry weight), fruit composition (degrees Brix, titratable acidity, pH, and color), and degree of rachis drying.

The effects of SO2 and O3 on the foliar nutrition of Scots pine, Norway spruce and Sitka spruce in the Liphook open‐air fumigation experiment

ABSTRACTFoliar elements were analysed in Scots pine, Sitka spruce and Norway spruce over a 6 year period before and during continuous exposure to SO2 and O3 in an open‐air fumigation experiment. Sulphur dioxide treatment elevated foliar sulphur concentration in all species, and there were increases in foliar nitrogen in the two spruce species but not in pine. The concentrations of cations were frequently increased by SO2 treatment, but there was no correlation between the sulphur concentration of needles and their total cation charge. SO2‐related elevations of foliar magnesium were correlated with the concentration of this element in soil solution, but the mechanism by which other cations were enhanced remains unclear. The only consistent effects on nutrient ratios were for SO2 treatments to increase sulphur/cation ratios.

Mineral nutrient deficiency increases the sensitivity of photosynthesis to sulphur dioxide in needles of a coniferous tree, Abies nordmanniana.

Abies nordmanniana (Stev.) Spach was cultivated in rooting media either rich in nutrients (control) or low in magnesium (low Mg) or low in magnesium and nitrogen (low Mg-N), respectively. Intact, attached needles were exposed, in the light (460 μmol photons m-2 s-1), to an atmosphere containing 1 ppm SO2 for 5 h. Measurements of light- and CO2-saturated rates of photosynthetic O2 evolution, A max, were performed before and after SO2 treatments. In needles from well fertilized plants, A max was high (about 50 μmol m-2 s-1) and was not affected by SO2. Needles from low-Mg and low-Mg-N plants had lower photosynthetic rates and showed a marked decline in A max in response to the SO2 treatment. Stomatal conductance was similar in the three groups of plants during SO2 treatments.

Seedling Responses of Five Species of Western Conifers to Simulated Ambient Sulfur Dioxide Exposures

Abstract Seedlings of ponderosa pine, Douglas-fir, white fir, Engelmann spruce, and subalpine fir were exposed continuously to charcoal-filtered (CF) air or one of three levels of a simulated ambient exposure typical of SO2 pollution near smelters in the western United States. Seedlings were exposed during winter-spring experiments for 60 days to hourly means of 17, 38, and 54 ppb in 1988 and 35, 57, and 99 ppb in 1989. Sensitivities of species to SO2 were determined from height growth, diameter growth, root, stem, and needle weights, and from foliar injury. Ponderosa pine in all SO2 treatments in 1989 had decreased diameter growth and decreased needle weights compared with those in CF air. In 1989, average diameter growth of Douglas-fir in all SO2 treatments was less than those in CF air. Diameter growth and needle weights of ponderosa pine were correlated in all SO2 treatments and CF air. Diameter growth and needle weights of Douglas-fir were correlated in all SO2 treatments. Tip necrosis of needles occurred on a larger proportion of seedlings of all species in high SO2 than on those in CF air. Ponderosa pine and Douglas-fir were about equally sensitive to SO2 and both were more sensitive than white fir. White fir was more sensitive to SO2 than Engelmann spruce and subalpine fir which were equally unresponsive to SO2. For. Sci. 37(6):1538-1549.

Lodging of winter barley (Hordeum vulgare L.) in relation to its degree of exposure to sulphur dioxide

SUMMARYPlots in a field crop of winter barley (Hordeum vulgare L. ev.‘Igri’) were exposed to SO2 concentrations of 50, 100 and 200 nl l−1 above ambient. During May 1984 the crop lodged owing to wind and heavy rain, and the severity of lodging was clearly related to the gas concentrations that the plants had experienced.Samples of stems from the experimental plots were tested to find how much force was needed to bend the basal internode. Stems of plants that had experienced SO2 elevations of 100 and 200 nl l−1 were weaker than those from control plots; stems of the plants exposed to 50 nl l−1 were the strongest of all. Investigation of stem anatomy showed that lodging resistance was correlated with stem anatomical attributes, and particularly with the thickness of pairs of contiguous walls of sclerenchyma cells.The differences in stem strength in the SO2 treatments probably arose from the effects of SO2 on plant growth earlier in the season.

Growth responses of maize, soybean, and tomato to sulphur dioxide and ozone exposure patterns utilizing an incomplete block factorial experimental design

Maize (Zea mays L.), soybean (Glycine max L.), and tomato (Lycopersicon esculentum Mill.) plants were grown in a controlled environment and exposed for 6 hr daily for 7 days to O3 at 0.15 μL L−1 and/or SO2 at 0.30 μL L−1 (daily exposures). Some plants exposed daily to O3 were also exposed to SO2 for 6 hr on the first, third, fifth, or seventh day of O3 exposure (variable exposures) and some plants exposed daily to SO2 were treated similarly with O3 to determine the growth effects of O3 or S02 pre- and/or post-treatments on S02 and O3 mixture response. Growth sensitivity to 6 hr S02 or 6 hr O3 treatments was generally affected by the previous history of O3 or SO2 exposure, respectively. Species differed in the number of days of O3 or SO2 treatments required to elicit maximum sensitivity to a single 6 hr O3 and SO2 treatment. Linear contrasts compared variable with daily exposures for the S02 and O3 regimes. Plants exposed to the gas mixture for a single day (variable exposures) tended to be smaller than those exposed to the gas mixture daily, with the exception of soybean exposed to SO2 during daily O3. The six treatments were carried out in eight exposure chambers, as a partially balanced incomplete block design in blocks of four due to separate environmental control of the exposure facilities. The partially balanced incomplete block design proved to be about 2.6 times as efficient as a complete block design. The inclusion of covariates further increased precision.

Nutritional Implications Associated with Increasing the Fermentability of Straw by Chemical and Enzymatic Treatments

Effect of increasing fermentability of wheat straw by SO2 or by SO2 plus cellulase on several nutritional parameters was studied in sheep with ruminal and duodenal cannulae. Content of cell solubles in the straw was increased from 21.9 to 48.4% by the SO2 treatment and to 74.6% by the combined SO2 plus cellulase treatment. The increase in the content of rapidly fermentable sugars of the straw was associated with a gradual decrease in the proportion of acetic acid and a concomitant increase of butyric acid in the rumen.Calculated values of organic matter digestibility of wheat straw were 50.2, 65.3, and 68.4% for the untreated, SO2, and SO2 plus cellulase treatments. Digestibility of the untreated straw cell walls was 55.6%; those of the SO2 and combined treatment diets were increased by 50 and 42% respectively. Amino acid profiles in the duodenal digesta were similar for all treatments despite differences in dietary N. The most intensive net synthesis of microbial amino acids occurred on the SO2 diet in which a net gain (10%) of N between feed and duodenum was obtained.

Measurement of Enzymatic Browning at Cut Surfaces and in Juice of Raw Apple and Pear Fruits

ABSTRACTReflectance procedures were developed to measure the extent of enzymatic browning at cut surfaces and in the raw juice of apple and pear fruits. Reflectance L and a measurements, made at transversely cut surfaces of plugs bored from fruit halves, were linear or bilinear with log time and related to the extent of browning in six apple cultivars. With apple and pear juices, tristimulus values changed linearly with time in samples undergoing browning. Differences between initial and final tristimulus values were better indices of browning than the slopes of time curves. The suitability of these procedures for evaluating the effectiveness of browning inhibitors was demonstrated with SO2 and ascorbic acid treatments.

Impact of SO 2 Exposure on the Response of Agropyron smithii to Defoliation

Agropyron smithii populations exposed to 3 controlled SO2 concentrations were defoliated either once or twice during the growing season at a light and a heavy intensity. The intensity and frequency of defoliation were most influential in determining growth and tillering responses. Defoliating twice, at either intensity, had a large negative impact on plant growth whereas compensatory growth occurred after defoliating once at either intensity. Sulfur dioxide alone had no significant effect on biomass or the number of tillers, even though sulfur accumulated approximately in proportion to exposure concentration. Sulfur dioxide exposure with the additional influence of defoliation affected both the regrowth of A. smithii in terms of biomass and tiller numbers and forage sulfur concentration. Decreased plant growth in response to SO2 plus defoliation was dependent on defoliation frequency, whereas the effect of SO2 plus defoliation on plant sulfur concentration was positive and negative and depended on a complex interaction of SO2 concentration and defoliation frequency and intensity. The results are discussed in relation to the shortand long-term compensatory growth potential of a system simultaneously exposed to grazing and air pollution and the potential effect on consumers. During the first 4 years of a field experiment designed to investigate the response of a native North American grassland to controlled low concentrations of sulfur dioxide, it was observed that exposures during the growing season had subtle, but potentially important effects upon the system (Lauenroth and Heasley 1980). For example, exposure of Agropyron smithii Rydb. to S02 reduced chlorophyll concentration (Lauenroth and Dodd 1981), increased sulfur concentration (Lauenroth et al. 1979, Milchunas et al. 198 la), decreased the functional lives of leaves (Heitschmidt et al. 1978, Milchunas et al. 198 lb), and decreased the amount of labile carbon stored in the rhizomes (Lauenroth and Heasley 1980). Regrowth of A. smithii in the spring or after defoliation is thought to be dependent upon carbohydrates stored in rhizomes and roots (Bokhari 1977). Before the SO2 treatments were begun the area had been grazed by cattle. Following exclusion of cattle, a significant year to year increment in rhizome biomass was observed on the control plot. This was interpreted as an indication of recovery from grazing. B3y contrast, rhizome biomass failed to recover on the 170 ,Ag . mSO2 treatment. This suggested that, although the mechanisms by which SO2 exposure and grazing effect plants are different, the response of the plants to SO2 or grazing may be similar and/or additive. Populations under stress are often considered to be more susceptible to damage caused by additional perturbations. Because of the importance of these grasslands to the livestock economy of the northern Great Plains and the high probability that coal combustion for electric power production will increase in this area, a field experiment was conducted to examine the potential interactions between defoliation and SO2 exposure on the native vegetation. The hypothesis was that defoliation would be more detrimental to Authors are associate professor, Range Science Department, and Natural Resource Ecology Laboratory; associate director, Natural Resource Ecology Laboratory, and associate professor, Range Science Department; research associate, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins; and professor, Range Management Division, University of Wyoming, Laramie. Manuscript accepted April 30, 1984. regrowth of A. smithii populations which had been exposed to S02 for 4 years than to populations not exposed to SO2.

Begasungsversuche mit SO2 und Ozon an jungen Fichten

Abstract Fumigation experiments with SO2 and ozone on young spruces. Needles of 5 year old Picea abies showed increased necrosis with increase in ozone or SO2 fumigation. Peroxidase activity increased without obvious injury after SO2 treatment. Soluble sulfhydril compounds were most suitable for detecting SO2 treatments. SO2‐ozone mixture produced an effect greater than SO2 or ozone alone.

THE EFFECTS OF FLUCTUATING CONCENTRATIONS OF SULPHUR DIOXIDE ON THE GROWTH OF PINUS SYLVESTRIS L. AND PICEA SITCHENSIS (BONG.) CARR

SummaryPlants of Pinus sylvestris and Picea sitchensis, initially at the end of their third growing season, were grown for 2 years and 1 year, respectively, in regimes of fluctuating sulphur dioxide (SO2) concentration. The four fluctuating regimes had mean concentrations of about 100 μg m−3 and peak concentrations of either 300 to 400 μg m−3 or 750 to 900 μmg m−3,* combined with durations of high concentration which were either short (mean ∼ 5 h) and frequent, or long (mean ∼ 20 to 30 h) and infrequent. Their effects were compared with a constant concentration of about 100 μg m−3 and with clean air.In the first year of treatment, effects on dry weight increment consisted of depressions in the root only, but marked chlorosis, necrosis and abscission of the leaves of Picea sitchensis were caused by SO2, while the leaves of Pinus sylvestris were hardly affected. By the end of the second year of treatment (Pinus sylvestris only) dry weight increase of the whole plant had been reduced by 14% in the constant concentration and in fluctuating regimes with peaks of short duration, and by 22% in regimes with peaks of long duration. All the SO2 treatments caused early fall of 3‐year‐old leaves during the second year of treatment of this species.A comparison of the treatments with the characteristic regime of fluctuating concentration in those parts of Britain where the mean annual ground level concentration of SO2 is around 100 μg m−3, leads to the conclusion that the main effect of this regime is attributable to its mean, rather than its peak concentration.

Postharvest Quality and Storage Life of Grapes as Influenced by Adding Carbon Monoxide to Air or Controlled Atmospheres

Abstract The effects of 10% carbon monoxide (CO) added to air or controlled atmospheres (2% O2 with or without 5% CO2) on quality and storage life of grapes (Vitis vinifera L. cv. Thompson Seedless) were compared with those of the conventional SO2 fumigation treatments for decay control. CO in air reduced respiration and C2H4 production rates, and retarded berry browning and softening, but was only partially effective in retarding decay beyond 2 months at 0°C. SO2 treatments were very effective in controlling the spread of decay, but brown discoloration of the berries increased, especially after 2 months at 0° or 1°. When combined with 2% O2 with or without 5% CO2, CO inhibited C2H4 production and retarded decay development, but the presence of CO2 increased brown discoloration of the berries. A combination of 2% O2 + 10% CO was as effective as SO2 in controlling decay of grapes held at 0° for up to 4 months and caused less browning and bleaching than SO2.

LITERATURE ABSTRACTS

GENERAL PRINCIPLES: Thermal Denaturation of Proteins in Post Rigor Muscle Tissue as Studied by Differential Scanning Calorimetry. Eva Stabursvik and Harald Martens.GENERAL PRINCIPLES: Effect of Milk Concentration on the Nature of Curd Formed During Renneting, A Theoretical Discussion. D.G. Dalgleish.GENERAL PRINCIPLES: Hardening of Food Texture Induced by Microwave Irradiation. III. Changes in Starch Granules Under Conditions of Limited Water. A. Higo, M. Okubo and S. MichikoGENERAL PRINCIPLES: Infared and Laser‐Raman Spectroscopic Studies of Thermally‐Induced Globular Protein Gels. A.H. Clark, D.H.P. Saunderson and A. Suggett.GENERAL PRINCIPLES: Electron Microscopy of Network Structures in Thermally‐Induced Globular Protein Gels. A.H. Clark, F.J. Judge, J.B. Richards, J.M. Stubbs and A. Suggett.GENERAL PRINCIPLES: Cs NMR in the Sol Gel State of Aqueous Carrageenan. Selective Site Binding of Cesium and Potassium Ions in Kappa‐Carrageenan Gels. H. Grasdalen and O. Smidsrod.GENERAL PRINCIPLES: Relationship of Chewing Sounds to Judgments of Food Crispness. C.M. Christensen and Z.M. Vickers.GENERAL PRINCIPLES: Apparent Activation Energy of Viscous Flow in Pectin Jellies. R.H. Walter and R.M. Sherman.GENERAL PRINCIPLES: Ultrastructural Examination of Egg Albumen Protein Foams. T.M. Johnson and M.E. Zabik.GENERAL PRINCIPLES: Network Structure in Gels of Rod‐like Polypeptides. K. Tohyama and W.G. MillerGENERAL PRINCIPLES: Dynamic Viscoelastic Properties of Gelatin Gels in Glycerol‐Water Mixtures. J.L. Laurent, P.A. Janmey and J.D. Ferry.INSTRUMENTATION & METHODOLOGY: A Simple Centrifugal Method for Measuring Expressible Moisture, A Water Binding Property of Muscle Foods. C.A. Jauregui, J.M. Regenstein and R.C. Baker.INSTRUMENTATION & METHODOLOGY: Measuring the Breakage Susceptibility of Shelled Corn. B.S. Miller, J.W. Hughes, R. Rousser and Y. Pomeranz.INSTRUMENTATION & METHODOLOGY: Measurement of Corn Kernel Hardness. T.L. Tran, J.M. deMan and V.F. Rasper.INSTRUMENTATION & METHODOLOGY: Measuring the Breakage Susceptibility of Soybeans. B.S. Miller, J.H. Hughes, Y. Pomeranz and G.D. Booth.INSTRUMENTATION & METHODOLOGY: Influence of Postmortem Aging Period on the Fragmentation Index of Bovine Longissimus Muscle. A.B. Cole Jr. and G. W. Davis.INSTRUMENTATION & METHODOLOGY: Low‐Shear, Small Volume Viscoelastometer. K.S. Zaner, R. Fotland, and T.P. Stossel.INSTRUMENTATION & METHODOLOGY: A New Method and Apparatus for Measuring Foam Stability. G. Nishoika (NASA, George C. MarshallOBJECTIVE MEASUREMENTS: The Effect of Stabilisers on the Viscosity of an Ice Cream Mix. John I.L. Cottrell, Geoffrey Pass and Glyn O. PhillipsOBJECTIVE MEASUREMENTS: Rheological Studies of Agar‐Agar Gels Prepared from Makusa (Gelidium Amansii) Gathered in Different Seasons. M. Watase and K. Nishinari.OBJECTIVE MEASUREMENTS: Effect of Sodium Hydroxide Pretreatment on the Relaxation Spectrum of Concentrated Agar‐Agar Gels. M. Watase and K. Nishinari.SENSORY MEASUREMENTS: Sensory Textural Properties of Stabilized Ice Cream. L.J. Moore and C.F. Shoemaker.SENSORY MEASUREMENTS: Evaluation of Textural Characteristics Produced in Cottage Cheese Creamed with Selected Dressings. H.R. Cooper and T.A. Watts.SENSORY MEASUREMENTS: Potential Fallacy of Correlating Hedonic Responses with Physical and Chemical Measurements. A.S. Trant, R.M. Pangborn and A.C. Little.FACTORS AFFECTING TEXTURE: Objective and Subjective Texture Evaluation of Irradiation Sterilized Meat Products. R.A. Segars, A.V. Cardello and J.S. Cohen.FACTORS AFFECTING TEXTURE: Effect of Lipophilization of Soy Protein on Its Emulsion Stabilizing Properties. H. Aoki, O. Taneyama, N. Orimo and I. Kitagawa.FACTORS AFFECTING TEXTURE: Changes in the Tenderness of Meat Cooked at 50–65d̀C. P.E. Bouton and P.V. Harris.FACTORS AFFECTING TEXTURE: Effect of Water Activity on the Sensory Crispness and Mechanical Deformation of Snack Food Products. E.E. Katz and T.P. Labuza.FACTORS AFFECTING TEXTURE: Determining the Radial Distribution of Specific Gravity Within Potato Tubers. A.R. Quarmby.FACTORS AFFECTING TEXTURE: Improved Method for Preparation of Fruit‐Simulating Alginate Gels. C. Pelaez and Marcus Karel.FACTORS AFFECTING TEXTURE: Recipes for Improvement of Scooperability of Ice Cream. F. Bray.FACTORS AFFECTING TEXTURE: Molds in Brined Cucumbers: Cause of Softening During Air‐Purging of Fermentations. R.N. Costilow, K. Gates and M.L. Lacy.FACTORS AFFECTING TEXTURE: Influence of Heat and SO2 Treatments on Some Quality Characteristics of Intermediate Moisture Bananas. A. Levi, J.R. Ramirez‐Martinez and H. Padua.FACTORS AFFECTING TEXTURE: Processing of Grapefruit Segments Containing Membranes. H. Hannan Jr.FACTORS AFFECTING TEXTURE: Physical Properties of Milk and Milk Products I Hardness, Breaking Energy and Elastic Modulus of Milk Rennet Curd. T. Ohashi, S. Haga, H. Fujino, S. Taniyama, K. Yamauchi and T. Akiyame.FACTORS AFFECTING TEXTURE: As measured with a rheometer, hardness, breaking strength and elastic modulus of rennet curd varied significantly among different milk samples. Positive correlations were found among these three physical parameters.FACTORS AFFECTING TEXTURE: The Influence of Collagen on the Rheological Properties of Meat Homogenates. M. Sadowska, Z.E. Sikorski and M. Dobosz.FACTORS AFFECTING TEXTURE: Effect of Heat Treatment on the Flow Properties of Aqueous Guar Gum and CMC Solutions. M.A. Rao, R.H. Walter and H.J. Cooley.FACTORS AFFECTING TEXTURE: Texture Profile Analysis of Patties Made from Mixed and Flake‐Cut Mechanically Deboned Poultry Meat. C.E. Lyon, B.C. Lyon, C.E. Davis, and W.E. Townsend.

Ozone and Sulfur Dioxide Effects on Tall fescue: I. Growth and Yield Responses

AbstractThe effects of ozone (O3) and sulfur dioxide (SO2) on growth and yield components of tall fescue (Festuca arundinacea Schreb. ‘Alta’) were studied in a greenhouse experiment. Four O3 treatments ranging from 0 to 0.30 ppm in equally spaced intervals and two SO2 treatments, 0 and 0.10 ppm, were arranged factorially in a randomized complete block design utilizing three blocks. Each block was exposed to the pollutants 6 h/d, once a week, for 12 weeks. Statistical analysis was by analysis of variance and regression techniques.Ozone significantly affected root/shoot ratio and all dry weight fractions. A reduction of total dry weight of 52.5% was found due to 0.30 ppm O3. A cubic regression model of O3 concentration on total dry weight accounted for 93% of the variation in total dry weight. Partitioning the dry weight into shoot and root components revealed a reduction in shoot weight of up to 46% and a reduction in shoot weight of up to 46% and a reduction in root weight of up to 63.6% due to the high‐O3 treatment. Both variables had significant cubic regressions of O3 on dry weight with the cubic model accounting for 93 and 89% of the variation in shoot and root weights, respectively. Root/shoot ratio declined from 0.58 for control plants to 0.41 for plants exposed to 0.30 ppm O3. A significant cubic regression of O3 on root/shoot ratio accounted for 78% of the variation in this variable. Tiller weight was also affected adversely by O3 with a linear decrease (r2 = 0.85) of > 44% at the highest O3 level. SO2 also affected tall fescue, but not nearly as severely as O3. Total dry weight was reduced by 7.3% due to SO2. Root weight was decreased by 11%, but shoot weight was unaffected. Root/shoot ratio was lowered about 7% due to the pollutant. Weight per tiller was unaffected by SO2. Number of tillers was significantly reduced by an interaction of the two pollutants. Neither O3 or SO2 had an effect singly, but at the high O3 level, the addition of SO3 caused an 18.6% reduction in number of tillers. This was the only significant pollutant interaction noted.

Effect of hydrolysing and oxidizing agents on the composition and degradation of wheat straw monosaccharides

Wheat straw (WS) was treated with 5% sodium hydroxide, ozone and 5% sulfur dioxide at 70°C for 72 h, and the effect of treatments on monosaccharide composition and in vitro degradability by rumen microorganisms was studied. The major sugars, glucose and xylose, comprising about 90% of the total monosaccharides in the untreated WS were mainly confined to the cell walls. SO2 exerted the greatest solubilizing effect, followed by ozone and NaOH; the respective values for the solubilized cell wall polysaccharides were: 26, 12 and 4.4%. One third of the total phenolics was oxidized by ozone, whereas, SO2 exerted mostly a solubilizing effect on this fraction, converting 75% of it into soluble phenolics. In the NaOH treated WS 41% of the total phenolics were soluble, as compared to 22% in the untreated. The in vitro digestibility of monosaccharides in the untreated WS were initially high: 50% and 58% for xylose and glucose, respectively and 63% to 80% for the minor sugars. The SO2 treatment resulted in an overall increase in digestibility of monosaccharides with values lying in the range of 90%. Sodium hydroxide was more efficient than ozone in enhancing the degradability of xylan and total sugars. The digestibility of cell wall sugars was increased from 52.4% to 84.4%, 63.4% and 72.3% by SO2, O3 and NaOH treatments respectively. Based on the present findings, it appears that wheat straw cell wall components are more sensitive to hydrolytic than to oxidative processes aimed at increasing its degradability by rumen microorganisms. SO2 exerted on WS a multi-effect which was particularly suitable for increasing the digestibility of monosaccharides.