Starch/Solute Interaction in Water Sorption as Affected by Pretreatment

The effect of the freeze-drying process on the structure of starch and starch-sucrose mixtures was studied. The technique of inverse gas chromatography was used to study the interaction between organic compounds (probes) and starch (hylon 7) as well as starch-sucrose mixtures. The structural and morphological characteristics of the starch-solute mixtures from the thermodynamic parameters of these interactions was also examined. The porous freeze-dried samples interacted more with certain organic probes compared with untreated starch as indicated by higher values of specific retention volumes (Vg_o). Untreated starch apparently interacted only on the surface with organic probes. Freeze-dried starch reacted only with polar organic probes, particularly those with hydrogen bonding propensity. Cluster analysis of the water sorption isotherms correlated with data obtained from the injected probes.     

Structural changes in meat during ageing

Summary. During the ageing of bovine muscle the most notable changes in the pattern of myofibrillar cross-striations are the complete disappearance of the Z lines and the lengthening of the A bands at the expense of the I zones. It is suggested that with the disintegration of the Z lines, the actin filaments of the I zones collapse onto the myosin rods, leading to apparent A-band lengthening. It is concluded that the weakening of the normally refractory Z lines of the myofibrillar structures is an event closely related to meat ageing.     

HPLC Determination of Carotenoids in Fruits and Vegetables in the United States

A study was conducted to determine alpha- and beta-carotene and beta-cryptoxanthin in twenty-two fruits and vegetables. Foods were obtained from wholesale distributors from five locations throughout the United States (Los Angeles, Dallas, Chicago, Miami, and Boston) three times during a year (November, March, and July). Mean vitamin A activity in retinol equivalents (RE) of each food along with average values for the individual carotenoids (μg/100g) are given. beta-Carotene was the most prevalent carotenoid. Carrots, beet greens, spinach, swiss chard and sweet potatoes had the most vitamin A activity. Analysis of variance indicated that there were no significant differences among either locations or time of analysis. A comparison was made between the new values and the ones listed in USDA Handbook No. 8 and revised Handbook No. 8–9. There were differences between the old and new values in 14 of the 22 fruits and vegetables analyzed.     

Starch/Sucrose Interactions by Organic Probe Analysis: An Inverse Gas Chromatography Study

The effect of freeze drying of high amylopectin starch was determined with samples of starch dispersed in water with or without solubilized sucrose. The X-ray diffraction data showed that this treatment disrupted crystalline structures of amylopectin and sucrose exposing additional sites for water sorption. This was shown also by sorption isotherms of the starch alone. The Hylon 7-sucrose freeze-dried samples produced a greater effect on sorption than did the corresponding Amioca freeze-dried mixtures. Organic probe analysis of the starch and starch-sucrose mixtures indicated that high amylose starches were more reactive with polar organic probes than high amylopectin starches when freeze-dried. Untreated high amylopectin starches were more reactive with probes in agreement with the water sorption data for a more branched polymer.     

Gas Chromatographic Determination of Sorption Isotherms of Vinylidene Chloride on Vinylidene Chloride Copolymers

A simple procedure for obtaining sorption isotherms from chromatographic peak shapes was applied to poly(vinylidene chloride-vinylch-loride 80:20) and poly (vinylidene chloride-actylonitrile 80:20) surfaces using vinylidene chloride as sorbate. Absolute values of the isosteric heat of adsorption (at constant uptake) increased with decrease in the amount of vinylidene chloride adsorbed, indicating a stronger monomer-polymer interaction at lower monomer concentrations. Absolute values of Gibb's free energy of adsorption increased with decrease in monomer concentration and temperature, indicating a more favorable monomer-polymer interaction at low temperatures and monomer concentrations. Data under present experimental conditions correspond to a strong thermodynamic polymer/monomer interaction leading to a substantially limited migration of monomer from a polymeric package into a food contacting medium.     

Rennet Coagulability of High-Heat Treated Milk Influenced By Time of pH Adjustment

The coagulability of high-heat treated (91°C for 16 or 60 set) milk was measured with a Formagraph. Coagulation (hysteresis) and curd formation by such milk was increased by direct acidification to pH<6.4 before rennet addition. Coagulation properties were increased greatly when such milk was pH-cycled (i.e., acidified to pH 5.5, held overnight at 4°C, then neutralized to pH 6.2–6.4) before rennet addition.     

Glycosylated Flavor Precursor Extraction by Microwaves from Grape Juice and Grapes

Because of their importance in grapes, an original method of extraction of glycosides from grape juice and grapes by microwaves was studied. Samples, immersed in a solvent, were subjected to microwaves in a microwave oven. The glycoside composition of the extracts was analysed by GC-MS. This method was compared to the method using a column of Amberlite XAD-2 resin, chosen as a reference method. Although a further purification of extracts was required, this method provided the advantages of rapidity, ease of extraction, and possibility to extract berries without deseeding and crushing. The reliability of the method was 97 to 85% for a large number of compounds and yields of extraction were nearly equal to those involving more complex extractions.     

ALTERATION OF GLUCOSINOLATE CONTENT, PATTERN, AND MUTAGENICITY OF CABBAGE (BRASSICA OLERACEA) GROWN ON MUNICIPAL SEWAGE SLUDGE—AMENDED SOIL

Cabbage (Brassica oleracea var. capitata) was grown on soil (control) or municipal sewage sludge-treated plots. The cabbage was freeze-dried and analyzed for glucosinolate content and pattern. Results showed that cabbage grown on sludge-amended soil contained only half the glucosinolate content of cabbage grown on the control plot. The pattern of individual glucosinolates present was also altered. The sludge-grown cabbage glucosinolate extract was shown to be mutagenic in the non-activated test system of S. typhimurium TA 100. Extracts of both sludge-grown and control cabbage were shown to enhance the mutagenicity on a dose-response basis of aflatoxin B₁, benzo(a)pyrene, and captan.