RHEOLOGICAL BEHAVIOR OF POMEGRANATE (PUNICA GRANATUM L.) JUICE AND CONCENTRATE

The rheological behavior of pomegranate juice (Punica granatum L.), prepared from fresh pomegranates, was studied as a function of solids concentration in the range 17.5–75°Brix at 10–55C, using a controlled stress rheometer. Concentration methods did not influence flow behavior. There were no significant differences (P > 0.05) between viscosity and activation energy values for the pomegranate juices concentrated by different methods. The juices exhibited Newtonian behavior regardless of the concentration method. The effect of temperature was described by an Arrhenius‐type equation with an activation energy in the range 5.34–32.2 kJ/mol depending on concentration. An exponential model described better the effect of the soluble solids on the viscosity and E_avalues. A simple equation was proposed for describing the combined effect of temperature and soluble solids content on the juice viscosity.     

ADHESION CHARACTERISTICS OF ISOLATED WAX SUBSTANCES FROM FRUIT CUTICLES RELATED TO OSMOTIC DEHYDRATION OF WHOLE FRUITS I. EFFECT OF TEMPERATURE AND PRELIMINARY TREATMENT

Adhesion behavior of cuticular wax isolated from cherries, plums and grapes, in a 70% sucrose solution, is the subject of discussion in the present work. Criterion is suggested for estimation of the effectiveness of preliminary treatment and temperature conditions in osmotic treatment of whole fruits. An apparatus is described for the determination of the contact angle θ_slv according to the method of the lying drop. Calculations are made of the energy characteristics, the energy of wetting Wslv and the adhesion work A_slv, of the three phase contact, isolated cuticular wax/70% sucrose solution/air, at temperatures from 20°C to 80°C.     

OSMOTIC DEHYDRATION OF MUSKMELON (CUCUMIS MELO): INFLUENCE OF BLANCHING AND SYRUP CONCENTRATION

The influence of blanching and syrup concentration on the quality parameters of osmo‐air‐dried muskmelon product was investigated. Fruit samples were dehydrated with sucrose solutions at 40, 50 and 60°Brix and the resulting products were analyzed for browning degree, ascorbic acid (AA) concentration and water activity. The values for all three parameters decreased as the syrup concentration increased. Blanching treatment before the osmotic processing had no effect on browning but caused a decrease in AA concentration. Osmotically dehydrated fruits showed no browning increase for at least 4 weeks at 2C. A decrease of about 60% in AA concentration was observed within the first 2 weeks at 10C. In contrast, AA loss was only observed after 2 weeks at 2C. The influence of storage time and temperature on AA retention was investigated by 2² factorial design. Statistical analysis of results showed that the two factors have a significant effect on AA retention. Osmotic dehydration may be an interesting alternative for processing of muskmelon as a pretreatment followed by cold storage or drying.     

BIOCHEMICAL CHARACTERIZATION OF BORAGE (BORAGO OFFICINALIS L.) SEEDS

Gas chromatography–mass spectrometry analysis of seed Borago officinalis essential oil (EO) revealed the presence of 16 volatile components. β-Caryophyllene (26%) and p-cymene-8-ol (19.7%) represented the major components, while nonadecane (0.7%) and hexanol (0.7%) were the minor ones. The EO composition was characterized by higher abundance of oxygenated monoterpenes (27.7%), followed by sesquiterpenes (26%). Fatty acid composition showed the predominance of linoleic (35.4%), oleic (24.2%) and γ-linolenic (20.4%) acids. Polyphenols were analyzed by reversed-phase high-performance liquid chromatography after acid hydrolysis of phenolic acid esters. Six phenolic acids were identified in seed extract and rosmarinic acid was the predominant one with 1.65 mg/g dry matter weight equivalent to 33% of total phenolic acids.

PRACTICAL APPLICATIONS

Borage ( Borago officinalis L.) is of great interest because of its medicinal and nutritional properties. In fact, thanks to its characteristic composition in fatty acids, particularly high levels of gamma-linolenic acid in its seed oil, borage has gained importance. The potent consumers of this medicinal plant are hypertensive and hypercholesterolemic people. Borage consumption is also recommended for people suffering from rheumatism and eczema.
Unfortunately, the knowledge about antioxidative/antiradical properties of borage is very scanty. So, recently, an extensive investigation was focused on the antioxidant properties of borage extracts. These extracts showed excellent antioxidant properties and their effects were attributed to their phenolic constituents. These antioxidants can be concentrated, either as crude extracts or individual phenolic compounds, to be used in highly unsaturated oils such as marine oils. Furthermore, borage consumption has been reported as a possible gastric cancer protective factor.     

OSMOTIC DEHYDRATION OF KIWIFRUIT (ACTINIDIA CHINENSIS): FLUXES AND MASS TRANSFER KINETICS

Pulsed‐Vacuum‐Osmotic‐Dehydration of kiwifruit (Actinidia chinensis) was studied using two kinds of osmotic solution: sucrose (65 Brix) and concentrated grape juice (63 Brix), three temperatures (25, 35 and 45C) and four vacuum pulse times (0, 5, 10 and 15 min). Experimental results enabled the mass transfer kinetics for water and solutes to be studied (compositional changes of the liquid fraction and changes in the liquid fraction/solid matrix ratio). The impregnation of samples, because of the vacuum pulse, was higher when concentrated grape juice was used as the osmotic solution, probably due to its lower viscosity. The effective diffusivity (D_e) was obtained for each experimental condition and the results show higher diffusivities for vacuum‐pulsed treatments, although differences between treatments with different vacuum‐pulse time could not be observed. D_e values were slightly greater for treatments with concentrated grape juice. The activation energies (E_o) were obtained by fitting the data to the Arrhenius equation.     

OPTIMIZING THE DEHYDRATION CONDITIONS OF GREEN BELL PEPPERS (CAPSICUM ANNUUM L.): QUALITY CRITERIA

Green bett pepper (Capsicum annuumL.) dices were dehydrated at different dry bulb air temperatures (55, 60, 65, 70 and 75C) and relative humidities (15, 20, 25, 30, 35 and 40%). Color, L-ascorbic acid and sugar retention were adversely affected by temperature and RH during dehydration. Loss of color and reduction in L-ascorbic acid and sugar were more prominent at the higher temperatures (70 and 75C) used. Sugar retention was negatively affected by drying, in that levels decreased, but no distinguishable pattern existed between the drying conditions and sugar retention. Optimum quality (maximum retention of color and L-ascorbic acid) green peppers were attained at drying conditions of 55 and 60C (15–40% RH) as well as at 65 and 70C (15% RH).     

LIPOLYTIC ACTIVITY OF ENZYMES FROM GERMINATING SEEDS OF SESAME (SESAMUM INDICUM L.)

Sesame ( Sesumum indicum ) seeds were germinated for seven days under laboratory conditions and the lipolytic activity of the defatted, dried seedlings was determined. Germination increased the lipolytic activity of sesame seeds and the highest activity was observed on day-4. The lipases of four days germinated sesame seeds were able to hydrolyze mainly the saturated fatty acids from seal blubber oil (SBO). Reaction temperature, incubation period and oil-to-seedling powder ratio had a significant effect on the hydrolysis of saturated fatty acids, thereby concentrating unsaturated (mono- and polyunsaturated) fatty acids of seal blubber oil.     

EFFECT OF PRESSURE-SHIFT FREEZING VERSUS AIR-BLAST FREEZING OF CARP (CYPRINUS CARPIO) FILLETS: A STORAGE STUDY

Intact carp (Cyprinus carpio) fillets were packaged under vacuum and pressurized at 100, 140, 180 and 200 MPa at 4C for 15 or 20 min. Changes in the lipid fraction and color of the fillets as well as the electrophoretic profiles of the fish proteins were studied to establish the best conditions (time and pressure) for pressure‐shift freezing the carp fillets. Thiobarbituric acid (TBA) values, free fatty acid (FFA) content and color parameters (L*, a*, b*) increased as the pressure level and pressurization time were increased. After 15 min of treatment at any pressure level, the intensity of the protein band with MW < 36 kDa decreased. With these results, the carp fillets were frozen using either pressure‐shift freezing (PSF) (140 MPa, ?14C for 12 min) or air‐blast freezing (ABF) (?20C for 4 m/s) and then stored at ?20C for 75 days. Changes in TBA values, FFA content, texture, total drip losses and size of ice crystal were evaluated. The TBA values and FFA content were relatively lower in the PSF samples than in the ABF samples. The freezing procedure did not seem to have a significant effect (P > 0.05) on the texture of carp fillets. PSF was more effective in reducing total drip losses in cooked samples compared to ABF treatment. Ice crystals found in the PSF fish samples were mainly intracellular, smaller and more regular in shape than those found in the ABF samples.     

RATE OF FREEZING AND INTEGRITY OF VEGETABLE TISSUES: IV: Observations on Summer Squash (Cucurbita pepo L.)

This paper reports histological observations on blanched and unblanched summer squash tunnel frozen at different rates. The detected textural damage consisted of detached cell layers, cell tearings, cavities, and various changes in the cytoplasm, nucleous, and starch granules. The number and extent of these damages increased as the freezing rate decreased. Blanching made the tissue more sensitive to freezing damage. With 5 mm thick slices, the critical freezing time is less than 15 min at - 35°C.     

EFFECT OF DIFFERENT TREATMENT PROCESSES AND PRESERVATION METHODS ON THE QUALITY OF TRUFFLES: I. CONVENTIONAL METHODS (DRYING/FREEZING)

Truffles are one of the major food ingredients of many favorite traditional dishes in the Middle East. Because of their short shelf life, truffles are considered a perishable commodity. Two varieties of local truffles were blanched in 2 or 4% boiling salt (NaCl) solutions for 2 or 4 min or by dry salting and or spraying with 5% vinegar. The treated samples were dried in an oven at 110C or were immediately frozen at ?18C and were stored for 1 year. In conclusion, color, texture and flavor were best preserved by blanching in 4% boiling NaCl solution for 4 min. Freezing was superior to dehydration as a preservation method.