Polyphosphates as inhibitors of surface mould growth on hard cheese during ripening

A novel treatment using polyphosphates to protect cheeses against superficial mould growth was assayed. The treatments were: control commercial paint with natamycin (I), commercial paint based on polyvinyl–water (II), immersion in a saturated solution of polyphosphate (III), immersion and commercial paint (IV), commercial paint of polyphosphate solutions (V) and immersion and commercial paint of a saturated solution of polyphosphates (VI). The cheeses were ripened for 6 months. Superficial mould growth was inhibited in groups IV and VI when compared to cheeses from the control group (I). Statistical sensory analysis made between cheeses from groups IV and I (control) showed no significant differences.     

Polyphenolic Compounds in Canned Tomato Pastes

SUMMARY– Polyphenolic compounds in canned pastes made from W-14.5 tomatoes ( Lycopersicum esculentum , Mill) were extracted with methanol and ethyl acetate. The compounds. were separated by two-dimensional paper chromatography with n-butanol-acetic acid-water (4:1:5 v/v) and 2% acetic acid as solvents. Twelve spots were found when the chromogenic reagent was FeCl₃K₃Fe(CN)₆. The individual compounds were identified by their R, values and color reactions with Fecl₃K₃Fe(CN)₆, diazotized paranitroaniline, Hoepfner, sodium borohydride, and vanillin-HCI reagents, fluorescent behavior, and absorption spectra. Present in the extracts of tomato pastes were two chlorogenic acid isomers, two caffeic acid derivatives, rutin, naringenin, caffeic acid, and ferulic acid. Naringenin and trans-chlorogenic acid were present in larger amounts than the other polyphenolic compounds.     

Gelling Properties of Actomyosin from Pre- and Post-Spawning Hake (Merluccius hubbsi)

The biochemical properties and the characteristics of heat-induced gelation of natural actomyosin (NAM) from pre- and post-spawning hake were studied. Mg²⁺ ATPase activity, reduced viscosity and myosin/actin mole ratio of NAM from post-spawning fish were higher than those of pre-spawning ones. Gelation of both actomyosin at 10 mg mL^?1 of protein concentration was optimal at 60°C and pH 6.0. The highest rigidity was reached at 0.40M and 0.44M KCl with NAM from pre and post-spawning hake, respectively. Irrespective of heating temperature, ionic strength conditions and at pH range 5.5–7.5, rigidity of post-spawning hake NAM gels was higher than those of pre-spawning fish. Scanning electron micrographs of pre- and post-spawning hake NAM showed “actin-type” and “myosin-type” ultrastructures, respectively.     

Thermal Denaturation in Fish Muscle Proteins During Gelling: Effect of Spawning Condition

We studied thermal denaturation of myofibrillar proteins from pre-and post-spawning hake by differential scanning calorimetry (DSC), and evaluated denaturation kinetics under both conditions. The denaturation enthalpies of all pre-spawning fish muscle extracts were less than those from post-spawning. The area under the DSC thermogram corresponding to myosin denaturation was smaller in myofibrillar extracts from pre-spawning than from post-spawning hake, while the areas corresponding to denaturation of actin were similar. Between 40 and 55°C the myosin denaturation rates were greater for post-spawning than for pre-spawning hake. Both entalphies and kinetic data indicated proteins of fish in a better biological condition (post-spawned) denature more rapidly and completely.     

Characterisation and evolution of grape polyphenol profiles of Vitis vinifera L. cv. Tannat during ripening and vinification

Background and Aims: Changes in different polyphenol families during grape ripening and vinification were determined in Tannat grapes. This was done to establish a polyphenol profile for Tannat grapes during ripening and for young wines. Methods and Results: We demonstrated, by high‐performance liquid chromatography with diode array detection and mass spectrometry (HPLC‐DAD‐MS) analysis, that the content of flavan‐3‐ols in Tannat seeds was higher than that reported for a large number of other grape varieties analysed. Forty per cent of the total flavan‐3‐ols in seeds were galloylated compounds, whereas the flavan‐3‐ol profile in skins was characterised by the absence of galloylated forms. Prodelphinidins in skins ranged between 30 and 35% with very low values for epigallocatechin. Epicatechin gallate was not detected in Tannat wine and galloylated forms represented a low percentage of total flavan‐3‐ols. Tannat grapes had very high concentrations of anthocyanins in skins with levels increasing during ripening. Eleven phenolic acids were identified in Tannat grape skins and wines, but only gallic and protocatechuic acids were found in the seeds. Conclusions: Tannat wines were shown to have one of the highest levels of phenolic compounds reported for vinifera grape varieties. The profiles for different polyphenol families present in Tannat grapes (skins and seeds) and wines were determined. Significance of the Study: The results presented will help to better understand the phenolic winemaking potential of this variety and its functional properties within food chemistry.     

SOY AND MEAT PROTEINS AS FOOD EMULSION STABILIZERS 1. VISCOELASTIC PROPERTIES OF CORN OIL-IN-WATER EMULSIONS INCORPORATING SOY OR MEAT PROTEINS

The creep compliance-time response of 50% (wt/wt) corn oil-in-water emulsions has been studied at a constant stress of 47.8 dyne cm⁻² over the pH range 2.5–7.5. The emulsions were stabilised by acid precipitated (APSP), 7S(7SPRF) or 11S(11SPRF) soy protein fractions, water soluble (WSMP) or salt soluble (SSMP) meat protein fractions. All the emulsions exhibited viscoelasticity. WSMP emulsions exhibited the highest initial viscoelasticity parameter values and this was attributed to the strong interlinking of WSMP loops adsorbed on the surfaces of adjacent oil drops. The parameter values of all the emulsions increased during the first 5–7 days storage and then they decreased. At any selected pH the 7SPRF emulsions exhibited the largest relative increase in parameter values. The changes in viscoelasticity during storage were explained on the basis of the relative effects of further protein loop interlinkage and drop coalescence.     

Thermal Denaturation of Hake (Merluccius hubbsi) Myofibrillar Proteins. A Differential Scanning Calorimetric and Electrophoretic Study

Denaturation of hake (Merluccius hubbsi) proteins was studied with DSC by monitoring T_max of transitions and denaturation enthalpies. Whole muscle free of connective tissue showed two transitions (T_max 46.5°C and 75.3°C), and ΔH of 4.27 cal/g. The exudative sarcoplasmic fraction showed three transitions (T_max 45.2°C, 59.0°C and 75.5°C) and ΔH of 3.92 cal/g. The sarcoplasmic proteins from whole hake muscle contributed to both denaturation peaks. Muscle depleted of sarcoplasmic proteins by chloride extraction showed a higher thermal sensitivity and a diminished denaturation enthalpy on the second transition. This suggested an additional effect of chloride upon actin in addition to sarcoplasmic protein extraction. pH had an effect upon the native conformation of thick filament proteins, specifically myosin.     

SOY AND MEAT PROTEINS AS FOOD EMULSION STABILIZERS 2. INFLUENCE OF EMULSIFICATION TEMPERATURE, NaCl AND METHANOL ON THE VISCOELASTIC PROPERTIES OF CORN OIL-IN-WATER EMULSIONS INCORPORATING ACID PRECIPITATED SOY PROTEIN

The rheological properties of concentrated corn oil-in-water emulsions stabilised by acid precipitated soy protein have been studied as a function of emulsification temperature, methanol and salt concentration. Viscoelasticity parameters were derived from the creep compliance-time response of the emulsions at a constant stress of 47.8 dyne cm⁻². All of the emulsions exhibited higher parameter values, both immediately after preparation and during storage, than comparable emulsions prepared at ambient temperature in the absence of methanol or NaCl. This was attributed to the increased unfolding of adsorbed protein molecules which permits greater interlinking, by hydrophobic bonds, of molecular segments projecting from the surfaces of adjacent oil drops.