A REVIEW OF METHODS FOR DETECTION OF STAPHYLOCOCCAL ENTEROTOXINS AND EVALUATION OF AN ENZYME-LINKED IMMUNOSORBENT ASSAY APPLIED TO FOODS

Immunological techniques for the detection of staphylococcal enterotox-ins, including gel diffusion, electroimmunodiffusion, passive hemag-glutination, radioimmunoassay, and enzyme-linked immunosorbent assay (ELISA) are reviewed in regard to their applicability to the routine analysis of foods. An ELISA employing minimal clean-up of food samples was evaluated and was capable of detecting 5 ng of staphylococcal enterotoxin A/g or ml which had been added to food.     

INFLUENCE OF YEAR,CULTIVAR AND FRUIT MATURITY ON QUALITY OF PEACH PUREE1

A 3-year study was conducted to evaluate the effect of year, cultivar and fruit maturity on the quality of peach puree and to determine the relative importance (RI) of these factors on the quality components hue angle (color), pH, acidity, soluble solids (SS) and SS/acid ratio. The results indicated that year, cultivar and fruit maturity had a strong effect and that they are very important in determining the quality of peach puree by affecting the different quality components. In general, fruit maturity had stronger RI than year and cultivar on the quality parameters studied. The data obtained for different maturities and cultivars fit a linear regression that accounted for 95% of the variability for all quality parameters measured. pH and SS/acid ratio increased while acidity and hue angle decreased and SS showed small or no increase as the fruit reached more advance stages of maturity.     

BI-CYCLICAL INSTRUMENT FOR ASSESSING TEXTURE PROFILE PARAMETERS AND ITS RELATIONSHIP TO SENSORY EVALUATION OF TEXTURE

The most popular instrumental imitative test is the Texture Profile Analysis (T.P.A.). It was originated in the General Foods Laboratories (Szczesniak et al. 1963) and adapted to the Instron by Bourne (1978). T.P.A. involves a double compression test that uses flat plates attached to an Instron Universal Testing Machine (I.U.T.M.). Several instrumental parameters can be extracted from the force/deformation curve generated by the test (e.g. hardness, cohesiveness, springiness, and chewiness). Recently developed in our laboratory, the Bi-cyclical Instrument for Texture Evaluation (B.I.T.E. master) uses the I.U.T.M. to generate its motion and features a set of artificial dentures as well as a tri-dimensional movement simulating a chewing motion. Five parameters were extracted from the force/deformation curve to evaluate their potential use for the prediction of cohesiveness.     

AN ENGINEERING METHOD TO EVALUATE THE CRISP TEXTURE OF FRUIT AND VEGETABLES

Precise measurements of the deformation and fracture behaviour of food can be difficult because of problems associated with the produce, for example, sample preparation, gripping, size and geometry. The aim of this study was to characterise fruits and vegetables in terms of fracture properties using an established engineering test method and geometry, the Single-Edge Notched Bend (SENB). The SENB geometry was found to be readily applicable to crisp food produce such as carrots, celery, and apples, which exhibit linear elastic behaviour up to fracture. Fracture toughness and fracture energies were found to be in the range 10–50 kPa m^1/2 and 40–400 Jm⁻², respectively. The structure of these materials was confirmed, using confocal microscopy, and related to the observed fracture behaviour. Cell size and intercellular spaces influenced the values of fracture toughness and fracture energy.     

CHARACTERIZATION AND IMPROVEMENT OF AN ASSAY FOR THIAMINE PYROPHOSPHATE WITH APPLICATIONS TO FRUIT TISSUE AT DIFFERENT STAGES OF THE CLIMACTERIC

A method for the measurement of thiamine pyrophosphate was reexamined with regard to optima for pH, temperature, incubation time, and pyruvate decarboxylase apo-enzyme concentration. The purified apo-enzyme was shown to be stable for 30 days at -80°C. Optimized conditions resulted in assays about 10 times faster than previously described. Increases in TPP content were noted during ripening of avocado and pear fruit however, the significance of the increases was circumscribed by limitations inherent to the extraction and assay procedures. Regulatory functions of TPP and their potential role in fruit tissues are discussed.     

EVALUATION OF INSTRUMENTAL METHODS FOR FIRMNESS MEASUREMENT OF FRESH AND CANNED CLINGSTONE PEACHES

The firmness of fresh and canned clingstone peaches was investigated using blade extrusion, back extrusion, and shear-compression instruments. The three techniques yielded results which correlated well among themselves and to sensory evaluation of peach firmness. Results indicate that high vacuum flame sterilization yields a canned product which is closer in firmness to fresh peaches than is the conventionally retorted product.     

EVALUATION OF SWEET POTATO CULTIVARS AND HEATING METHODS FOR CONTROL OF MALTOSE PRODUCTION, VISCOSITY AND SENSORY QUALITY

Two varieties of sweet potato were subjected to four cooking temperature‐time combinations. A fifth treatment involved adding maltose syrup. Raw comminuted sweet potato mash and cooked sweet potato puree were evaluated for total solids, alcohol insoluble solids, commonly occurring sugars, viscosity (puree only) and for starch gelatinization temperatures. The uncooked Owairaka Red variety was higher in total solids and in alcohol insoluble solids than the Toka Toka Gold. With the exception of the cooked puree with added maltose, baking at 200C resulted in puree with the highest maltose levels. A very fast cooking procedure tended to result in puree with lower levels of maltose and high viscosity. Sensory studies revealed that the Owairaka Red variety produced puree with more viscous and adhesive mouth feel. It was concluded that cooking alone could not be used to optimize both maltose production and viscosity.     

EVALUATION OF DUCKLING BREAST MEAT SUBJECTED TO DIFFERENT METHODS OF FURTHER PROCESSING AND COOKING

Breast fillets (128 total) deboned from commercially processed 7-week-old Pekin ducklings were subjected to one of four tenderization treatments: control, mechanically tenderized, marinated, or tenderized and marinated, and one of two cooking methods, oven-baked or gourmet-cooked. Treatments were evaluated for cooked yield and tenderness. Mechanical tenderization resulted in the lowest cooked yield, 60.0%, followed by the control, 64.5%. Mechanical tenderization and the control treatment were not significantly different for shear, with an average of 7.0 kg shear/g sample. Marination, with or without mechanical tenderization, resulted in signficantly greater cooked yield, 72.6 and 72.9 % respectively, and more tender meat, 4.9 and 5.1 kg shear/g meat respectively. Oven baking resulted in a signficantly greater cooked yield than gourmet cooking. Results indicate that marination, with or without mechanical tenderization, can significantly improve the cooked yield and tenderness of duckling breast fillets.     

36—AN ASSESSMENT OF METHODS OF TEST OF CARPETS FOR FLATTENING,CHANGE OF APPEARANCE,AND LONG-TERM WEAR

The Textile Institute Carpet Testing Working Party reports that agreement between laboratories using the WIRA Dynamic Loading Machine is satisfactory and that the correlation between thickness loss during the test and that due to flattening in a busy corridor at Harrods was very high. Pooled results from several laboratories using the Tetrapod Walker (without step) showed good agreement with rankings for change of appearance in corridors, and the test is recommended for direct visual comparisons between carpets tested at the same time. The rankings for long-term durability by the Tetrapod Walker when used with the step did not correspond with the wear of a wide range of carpets in a corridor. Variation between laboratories using the WIRA Carpet-abrasion Tester was high (especially for carpets containing polyamide fibre) and the correlation with long-term wear in a corridor not satisfactory for carpets differing in construction and fibre type.     

AN INSTRUMENT FOR MEASURING RHEOLOGICAL PROPERTIES BY BENDING. APPLICATION TO FOOD MATERIALS OF PLANT ORIGIN*

A new instrument, the MITEX MK II Bending Tester, is described as a means of measuring the following rheological properties of solid foods: bending moment, curvature, bending rigidity, modulus of elasticity, curvature set and bending moment loss. Equations applicable to bending and results of measurements on samples of celery, carrot, apple and potato are presented. Changes of the modulus of elasticity in relation to the time of exposure of sample strips to the ambient atmosphere, and graphical and mathematical treatment of the data for estimating a total ‘adjusted time’ (age) of a particular sample are discussed.     

INSTRUMENT FOR MEASURING BIND STRENGTH OF RESTRUCTURED AND EMULSION-TYPE MEAT PRODUCTS1

A sensitive and inexpensive penetrometer is described, consisting of a mounted rod and polished steel ball that may be advanced downward at variable speed through meat slices mounted on a plexiglass cylinder. The slice + mounting cylinder was placed on a top-loading balance, tared to zero, and centered under the penetrometer rod. Bind strength was measured as the peak force (g) required for the steel ball advancing at 2.0 cm/min to penetrate the meat slice. Data points (grams force versus time) were collected and plotted using an IBM-compatible personal computer and printer. Since the balance collected gram values continuously, a QuickBasic program was developed, allowing the user to specify the time interval (1,2,5 s, etc.) between recorded values. Bind strength of turkey rolls was increased by finely chopping the emulsion (vs. coarsely-ground samples), and by inclusion of 3% nonfat dry milk. Whey protein concentrate (3%) increased bind strength of finely chopped, but not coarsely ground rolls.     

RELATIONSHIP OF TREATMENT OF FRESH STRAWBERRIES TO THE QUALITY OF FROZEN FRUIT AND PRESERVES1

‘Cardinal’ strawberries were hand picked and stored 1 day at 21°C to enhance softening. Three separate preprocessing experiments were conducted to determine the effects of style of pack, 0.18% calcium (Ca) dips, 0.3% low methoxyl pectin (LMP), 40° Brix sucrose dips, heat of 70°C, vacuum at 172 mm Hg and drying to 70% moisture on quality and firmness of frozen-then-thawed and preserved strawberries. The greatest firming effect on frozen-then-thawed fruit was due to Ca and pectin. Sliced fruit was firmed more than whole fruit by the Ca and pectin treatments. Drained weight loss was reduced by pectin, Ca, sucrose, heat and vacuum in frozen-then-thawed fruit. Drained weight losses were the same or greater among treatments in preserves. The firmness and wholeness of preserves was increased by Ca, vacuum, 40° Brix sucrose, heat and to a lesser extent drying, but individual effects were not additive. The drying treatment reduced color quality.     

EVALUATION OF PROCESSES TO ENHANCE GRAIN AND MEAT COPRODUCTS1

Blends of soybean meal (SBM) and pork red blood cells (RBC) or stick water (SW) were extruded at different extrusion temperature profiles using a laboratory‐scale single screw extruder. The ratios of SBM:RBC were 90:10, 85:15, and 80:20 on a dry basis. The ratio of SBM:SW was 80:20 on a dry basis. Ground extrudates were analyzed for physical and nutritional properties which indicate the suitability of each treatment for use in feed processing systems. As screw speed increased from 60 to 120 rpm, the protein digestibility of the ground extrudates from the blends of SBM with 20% RBC increased from 94.4 to 97.1% at an extrusion temperature of 90C, and from 89.1 to 93.1% at an extrusion temperature of 130C. The protein digestibilities of the ground extrudates decreased as RBC content and particle size of the SBM increased. The protein digestibilities of the extrudates from the blends of SBM with RBC and SW decreased as extrusion temperature increased and screw speed decreased. The equilibrium moisture content of pelletized extrudates was lower than that of ground extrudates at each water activity tested. The extrudates from the blend of SBM with RBC had increased protein content and quality because of an improved balance of essential amino acids compared to SBM alone.     

EFFECT OF DIFFERENT METHODS FOR APPLICATION OF AN ANTIFOG SHRINK FILM TO MAINTAIN CAULIFLOWER QUALITY DURING STORAGE

Abstract The objective of this study was to evaluate the use of an antifog shrinkfilm, as an overwrap, sealed bag, vacuum–sealed bag, or vacuum– and heat–sealed bag, to maintain the postharvest quality of cauliflower during storage. The antifog shrink film improved quality retention and cauliflower packaged using any of the four methods exhibited less weight loss than controls (unwrapped) after 23 days in storage at 0–1C or 10C. The overwrap and sealed bag treatments resulted in higher appearance ratings and less curd browning and butt discoloration after storage at 0–1C. Shrinking the film with heat and/or vacuum may have damaged the tissue, providing a more favorable environment for microorganism growth, since more decay was found on these curds.