Abstract: Aqueous extraction of hydrocolloidal gum from flaxseed was optimized using response surface methodology. Extraction temperature (25-100°C), pH (2.0-7.0) and water:seed ratio (6.0-20.0) were the factors investigated with respect to yield, apparent viscosity and protein content of the final gum extracts. Temperature and pH were found to have a significant influence on both yield and quality of the extracted crude gum while the water:seed ratio had only minor effects. Optimum conditions for the extraction were a temperature of 85-90°C, a pH 6.5-7.0 and a water:seed ratio of 13. In addition, steady shear and small strain oscillatory tests on aqueous dispersions of gums, extracted under various conditions, were conducted to assess the impact of extraction conditions on the rheological properties of the flaxseed gum preparations.

Abstract: Inactivation of microorganisms in a semisolid model food was investigated using pulsed electric fields. Three microorganisms, Escherichia coil (ATCC 11229). Staphylococcus aureus (ATCC 6538) and Saccharomyces cerevisiae (ATCC 16664), were inoculated into a model food (potato dextrose agar) in fluid form and treated with high voltage pulsed electric fields (PEF) in semisolid form. The PEF microbial inactivation was proportional to the number and duration of pulses. Five to six log cycles of microbial inactivation were obtained for the three microorganisms tested in the model food. Microbial inactivation in this semisolid model food was found sufficient for the purpose of food pasteurization.

Abstract: Simultaneous dewatering and salting of cod fillets was achieved by soaking them in mixed concentrated solutions (sucrose/salt or corn starch syrup/salt) at low temperature. Water loss, sugar gain and salt gain kinetics, as well as sugar/salt interactions were studied. The results showed how the presence of sugar can enhance water loss, and hinder salt entrance. The use of high molecular weight sugar prevented sugar entrance and allowed a good dehydration. These results revealed that this operation is particularly interesting as an alternative to traditional cod processing. In fact, process duration can be reduced, water loss and salt entrance better controlled.

Abstract: Osmotic dehydration is used as one of the upstream processing steps (separation of kernel from shell) during wet processing of coconut. Water loss from the coconut increased with the increase in temperature and concentration of the osmotic solution. A correlation has been proposed for the reduced weight based on Fickian diffusion as a function of temperature, concentration and immersion time. High correlation was observed between experimental and predicted values.

Abstract: Eighteen commercial enzymic preparations have been tested for their ability to release ferulic acid from primary cell-walls of sugar-beet pulp. Three release patterns were found: (a) no or little, esterified ferulic acid; (b) only esterified ferulic acid; or (c) a mixture of free and esterified ferulic acid. No enzymic complex released only free ferulic acid. Release kinetics were studied on two complexes, 'Hemicellulase REG II' (Gist-Brocades), which released the highest amount of esterified ferulic acid, and 'Pektolase LM' (Grindsted), which released one of the highest amounts of free ferulic acid with the lowest proportion of esterified ferulic acid. 'Pektolase LM' digested sugar-beet pulp rapidly, first releasing esterified ferulic acid, which was later deesterified. 'Hemicellulase REG II' showed an initial lag phase followed by fast liberation (between 32 and 48 h of incubation) of esterified ferulic acid. Sugar-beet pulp hydrolysates from 'Pektolase LM' and 'Hemicellulase REG II' were fractionated on DEAE Sephacel. The results showed that esterified ferulic acid was present either linked to fragments of pectic polysaccharides poor in arabinose (∼40% of esterified ferulic acid injected) or to arabinose oligomers (∼60%).

Abstract: A microbiological study of each stage of the marination process of Engraulis achoita was conducted to determine specific flora and effectiveness. The behaviour of three kinds of raw materials (fresh, pre-salted and frozen anchovy) was assessed. Micrococcus sp. and Lactobacillus sp. were identified at each stage of the process for all the raw materials studied. Microbiological and sensory results indicate that all raw materials used were suitable for marinating.

Abstract: The effects of heat treatment and no heat treatment on the nutritional composition, antinutritive materials and functional properties of fenugreek seeds were studied. The raffinose, stachyose and verbascose were eliminated by germination, and the levels of phytic acid, tannic acid and trypsin inhibitor were reduced by it. However, heat treatment destroyed most of the trypsin inhibitor activity and verbascose and reduced the levels of raffinose, stachyose, phytic acid and tannic acid. Fenugreek seeds were a good source of essential amino acids especially leucine, lyisne, total aromatic amino acids and tryptophan. Heat treatment and germination decreased the sulfur-containing amino acids and tryptophan contents. Both treatments improved the in vitro protein digestibility. Fenugreek seeds were rich in Na, Ca, Cu and Fe. All treatments decreased the level of mineral content with the exception of Na, P and Zn for germination treatment. The major protein fractions in fenugreek seed were albumins (470 g/kg) and globulins (200 g/kg). Fenugreek seeds showed excellent functional properties. Heat treatment improved the water absorption capacity while germination improved the fat absorption capacity. However, both treatments decreased the nitrogen solubility index. Emulsifying activity was not affected by germination, while heat treatment did not affect emulsion stability. Fenugreek seeds could potentially be added to food systems such as bakery and ground meat formulations, not only as a nutrient supplement but also as a functional agent in these formulations.

Abstract: The potential of different commercial dairy starter cultures to form volatile organic compounds was assessed. Special interest was taken in the so-called minor constituents that are present in the low μg/kg range in the aroma of the end products of the investigated starter cultures. Volatile organic compounds produced by the starter bacteria are formed during production or within the first 24 h of storage. Quantitative changes that occurred after 2 and 4 wk proved to be less significant. Many of the aldehydes (pentanal and homologues up to undecanal) as well as some alcohols (1-propanol, 1-butanol, 1-pentanol) present in fermented dairy products were not produced by starter bacteria but originated from the milk. Only five of the compounds (dimethyl sulfide, 2,3-butanedione, 2,2-pentanedione, limonene and undecanal) together with ethanol are considered to have an impact on the resulting aroma, providing odour unit values >1.5. Using multiple stepwise regression analysis it was possible to differentiate between the five different culture types, and to discern the age of an unknown sample independent of its culture type.

Abstract: The purified triacylglycerol fraction of rapeseed oil was used as a food lipid model to study the effects of β-carotene and γ-tocopherol on its oxidative stability in light. The triacylglycerol fraction of rapeseed oil was oxidized under fluorescent light at 25°C. Oxidation was followed by measuring peroxide value and the consumption of antioxidants. Under air, β-carotene (20 μg/g) was a pro-oxidant, whereas γ-tocopherol (20 μg/g) was an effective inhibitor of lipid oxidation. When both β-carotene (20 μg/g) and γ-tocopherol (20 to 50 μ/g) were present together, the oxidation was inhibited more effectively than by γ-tocopherol alone. Our findings suggest that there is potential antioxidant benefit in combining β-carotene and γ-tocopherol in food systems.

Abstract: The ripe Brazilian tomato cultivar 'Santa Cruz' (10 sample lots) presented a mean composition in μg/g of 3.7 cis-phytofluene, 5.1 trans-β-carotene, 0.4 trans-ζ-carotene, 0.7 trans-γ-carotene, 3.0 cis-lycopene and 31.1 trans-lycopene. Cis-isomers of β-carotene, not detected in the fresh tomato, appeared in the processed products (39 samples). The juice which received the mildest heat treatment had only 0.01-0.02 μg/g 13-cis-β-carotene. In the puree and paste, O.1 to 3.8 μg/g 13-cis-β-carotene and not detected to 1.1 μg/g 9-cis-β-carotene were encountered. In ketchup, the ranges were 0.2-0.6 μg/g 13-cis-β-carotene and 0.4-0.8 μg/g 9-cis-βcarotene. The vitamin A value ranges (RE/100 g) were 63-101, 25-38, 46-160, 54-203 and 54-79 for fresh tomato, juice, puree, paste and ketchup, respectively. The corresponding lycopene ranges (μg/g) were 12-73, 53-68, 56-273, 110-240 and 59-143. The tomato paste, the most concentrated product, had higher vitamin A value and lycopene content, but at lower levels than expected, indicating losses during the more drastic processing.

Abstract: The aim of this study was to apply a standard addition method to quantify volatile organic compounds in pasteurized milk and fermented dairy products. Thirty-three volatile organic compounds detected in the headspace of milk or fermented dairy products were added in various concentrations to pasteurized milk as a reference and chromatographically analysed by a combination of dynamic headspace analysis and GC-MS. The original concentrations in milk of the added compounds and their respective 95% confidence intervals were calculated by means of linear regression analysis. With the exception of ethanal all tested compounds resulted in usable linear regressions and the calculated concentrations in milk generally agree with data found in literature. Ethanal excepted, the applied dynamic headspace GC-MS method provides accurate results for the quantification of volatile organic compounds in milk. Response factors calculated from data of the linear regression analysis in milk also allow quantitative determination of volatile compounds in fermented milks, since their matrix effect appears to be the same as for milk.

Abstract: The interactions between model wine aroma compounds—limonene, isoamyl acetate and ethyl hexanoate—and several polysaccharides—modified corn and waxy corn starches, dextrine, dextrans, hydroxypropyl celluloses and galactomannans—were studied using the exponential dilution technique. Information concerning the nature and the intensity of these interactions were obtained from the study of the variation in the reduced infinite dilution activity coefficient γi∞Gamma; as a function of the polysaccharide weight fraction. Retention of aroma compounds was detected for all the compounds studied except for dextrans, and in this case a salting-out effect was developed. The biphasic curve obtained for modified starch agrees with the presence of two binding modes corresponding to the formation of amylose and amylopectine inclusion complexes. A rapid decrease in the volatility of ethyl hexanoate and limonene (30 to 80%) was obtained at 0.01 weight fractions for galactomannans and hydroxypropyl cellulose; the study of interactions between volatile compounds and these polysaccharides were limited by the strong viscosity of their solutions. In the case of dextrin, the linear decrease in γi∞Γ agrees with the existence of hydrophobic interactions. A 50% decrease in γi∞Γ was obtained for a 0.04 weight fraction of this compound which was selected for the synthesis of a model glycopeptide.

Abstract: A fibre fraction (FF) was obtained from the residue that remained after pectin extraction of orange peels by nitric acid. The FF contained 213 g/kg soluble and 626 g/kg insoluble dietary fibre, 69 g/ks protein, 31 g/kg total sugars and 33 g/kg ash on a dry basis. The cellulose content of the FF amounted to 370 g/kg, the hemicellulose to 152 g/kg and the uronic acids to 281 g/kg. The neutral sugars composition of cellulose and hemicellulose was analysed by HPLC. The mineral content of the FF was determined. FF had water and oil absorption capacities, colour and pH comparable with commercial fibres.

Abstract: Several commercial enzyme preparations were evaluated as to their suitability for enzymatic peeling of grapefruit. The best pectinases were found to be those which contained high concentrations of polygalacturonase, pectin-transeliminase, and pectin esterase. A cellulase was also needed to achieve satisfactory peeling. The optimum process included scalding, scoring, vacuum infusion of the enzyme solution, pH stabilization, incubation (35 min at 40°C), and rinsing. The enzymatically peeled fruit had a good appearance, was firmer than that obtained by the conventional method. The enzyme solutions could be used for several consecutive peeling runs, after restoring them to their initial activity. Enzymatic digestion of grapefruit segment membranes was also achieved, and a very firm and shiny product was obtained.

Abstract: To reveal the flavour differences in puff-pastries prepared by using butter (I) or margarine (II) the most important odorants in aroma extracts of both pastries were compared by application of aroma extract dilution analyses. The data revealed high FD-factors for δ-decalactone, (E)-2-nonenal, 4-hydroxy-2,5-dimethyl-3 (2H)-furanone (HDF), butanoic acid and 3- and 2-methyl-butanoic acid in I, while (Z)-2-nonenal, 4.5-epoxy-(E)-2-decenal, (E,Z)-2,4-decadienal, (E)-2-nonenal and HDF were the most odour-active compounds in II. A calculation of odour activity values (OAV; ratio of concentration to odour thresholds) confirmed that compared to I especially the significantly higher OAV's of the metallic smelling 4,5-epoxy-(E)-2-decenal and the fatty, green smelling (E,Z)-2,4-decadienal in combination with the lack of the coconut-like smelling δ-decalactone in II are mainly responsible for the differences in the overall flavours of both products. In addition, a quantification of diacetyl in I indicated that during baking a significant degradation of this key butter odorant takes place.

Abstract: The viscosities of glucose, sucrose, and maltodextrin solutions coexisting with ice were measured by rotational viscometry. Samples were prepared by forming a shell of pure ice in a stainless steel tube immersed in a cooling bath, then introducing aqueous solutions at concentrations corresponding to the ice-melt equilibrium temperature. Temperature dependence of viscosity was analysed in terms of Arrhenius, VTF, WLF, and power-law models. Two glass transition reference temperatures were used with the WLF and power-law models: (1) Tg associated with the transition from liquid to glass and (2) Tg′ associated with the transition to glass from a maximally freeze-concentrated solution. Plots of Logη vs I/T were fairly linear for each solution, but each displayed a unique slope with EA ranging from 168 kJ/K mol to 464 kJ/K mol. WLF and power law models gave a linear fit to all solutions when Tg was chosen as the reference temperature. Regression analysis gave constants of C1 = 16.5 and C2 = 37.5 for WLF (Γ = 0.95), and κ = 1018.6 and m = 8.5 for power-law (Γ = 0.97) models.

Abstract: Vacuum osmotic dehydration as a novel method of partial dehydration of fruits leads to a special behavior of mass transfer in fruit-sugar solution systems. Vacuum treatments intensify the capillary flow function and increase the water transfer ratio significantly. A mathematical model is proposed to describe the total water transfer ratio which results from a combination of traditional Fickian diffusion and vacuum capillary flow of water during vacuum osmotic dehydration. Experiments with apricots were carried out at different pressures and temperatures in 65° Brix sugar solution. The experimental results verify the theoretical analyses and assumptions for total water transfer ratio during the first hours of vacuum osmotic dehydration.

Abstract: An enzymatic peeling process for Valencia oranges and pomelo was optimized. The procedure for Valencia included: scoring of peels; vacuum infusion of the enzyme solution which consisted of pectinases and cellulase; incubation (20-25 min) at 40°C; and rinsing. The peeling process for pomelo included: scalding; removing of the peel near the stem; scoring; vacuum infusion of enzyme solution; incubation at 40°C for 50 min; and rinsing. The fruit obtained by enzymatic peeling was firm and had a very good shiny appearance. The enzyme solution could be used for two consecutive peeling cycles in the case of oranges, and in the case of pomelo after restoring it to the initial activity.

Abstract: Three types of lactic starters of Streptococcus salivarius ssp. thermophilus 404 and Lactobacillus delbrueckii ssp. bulgaricus 398 have been produced by controlled pH batch cultures: pure starters, mixings of pure starters and mixed starters. They were compared according to their viability and their acidification activity after the different steps of their production and during storage. At the end of the batch cultures, the acidification activity, characterized by the maximum acidification rate in milk, was 40% higher for the starters issued from the mixed cultures or the mixings of pure cultures with regard to the pure starters. During the concentration, freezing and freeze-drying processes, tea significant alteration of the activity of the starters was observed. The viability of the starters, during 24 wk of preservation after freezing (-75°C) or freeze-drying (4°C), decreased continuously. This decrease was slightly faster in the case of the starter obtained from a mixed culture. The starters were more resistant during storage in a frozen state than in a freeze-dried state. Finally, thanks to the use of a well normalized procedure, the acidification activity was not altered during the storage of each type of starter.

Abstract: A steady state mathematical model which describes a natural gas indirect fired baking tunnel-oven is presented. Heat and mass transfer were studied. Individual heat transfer modes taken into account were radiation, convection and conduction. It was assumed that the baking chamber was homogeneous between roof and base. A homogeneous moisture and temperature distribution was assumed for the biscuit. The flow of air inside the oven and the drying of the biscuit were studied. A water activity model at high temperature was used. The model simulations provide spatial distributions of temperature and moisture of the biscuit, and temperature and hygrometry of the air. Experiments were performed at different baking conditions. Data were compared with numerical results. Good agreement was obtained between the experimental results and the model predictions.

Abstract: Textural and stress relaxation properties of potatoes and carrots were determined in their raw state, and at product temperatures of 30, 40, 50, 60, 70, 80 and 90°C during cooking. Zp (a temperature interval to make a 10-fold change in quality) values for these properties were obtained by computing the reciprocal of the slope of a linear regression of the logarithm of the properties as a function of product temperature. Textural properties were found to be suitable to monitor potato cooking, and viscoelastic and textural properties to monitor carrot cooking. For potatoes, Zp values for hardness, springiness, cohesiveness, and minimum and maximum penetration forces were 34.6, 132.7, 162.4, 64.6 and 61.4°C, respectively. Similarly, for carrots, Zp values for hardness, and elastic stresses were 31.6, 35.0 and 62.0°C, respectively.

Abstract: The taste and odour properties of 20 samples of Parmigiano-Reggiano cheese were individually related to their volatile and non-volatile components using partial least squares analysis as the multivariate regression technique. Odour intensity, taste fragrancy and staleness were three sensory attributes involved in significant relationships with two major chemical classes (esters and free fatty acids) and with selected volatile (short-chain branched alcohols, sulphides) and non-volatile (free amino-acids, salt) compounds. The combined set of sensory and chemical data, subjected to Principal Components Analysis, exhibited two major changes in the sensory properties of cheese, as possibly being affected by salt-controlled chemical patterns; the score-plot of the samples as regards the first two principal components showed that winter cheese was separated from cheese manufactured the rest of the year.

Abstract: A simulation of one-dimensional magnetic resonance projections of cherries, showed a significant difference between projections of cherries with and without pits. Projections of cherries in a 2-T magnetic field and a 100 mm Birdcage coil were used for detection of hidden pits. When cherries were randomly oriented 45 of 51 (88%) brined cherries with pits and 19 of 30 (63%) pitted cherries were correctly classified. A great improvement was achieved with oriented cherries: 29 out of 30 cherries with pits and 29 out of 30 pitted cherries were correctly classified. Detection rate may reach hundreds of cherries per second. This method could be applicable to detection of pits in olives and dates.

Abstract: Four different types of ice cream bases containing 125 g/kg butter were prepared with vanilla flavours. The five different types of flavours included a CO2 extract, an oleoresin, an extract, a natural flavour and vanillin. A professional descriptive panel carried out flavour and texture profiling of the 20 ice cream samples representing each combination of flavour and base. The data were analysed by 3-way ANOVA, Principal Component Analysis (PCA) and Cluster Analysis. Results indicate that the nature of the base is very important to flavour perception. Modifying fat distribution in the finished product influences the flavour release.

Abstract: Some major cider taste components (organic acids, sugars, alcohols and pectin substances) together with the microorganisms responsible for fermentations were determined in 12 ciders obtained by different technological methods in order to evaluate the quality of cider obtained. An analysis of variance revealed that the speed of pressing and the clarification system were the main factors influencing the efficiency of alcoholic fermentation, the speed of malolactic conversion and the microbiological stabilization of the cider.

Abstract: The steady and dynamic shear rheological properties of mesquite seed gum (MSG) solutions were measured at various concentrations (0.4-2.0 g/100 mL). The intrinsic viscosity was 240.5 mL/g. The Cross flow model provided a better fit on the shear rateapparent viscosity data than the Carreau flow model. The coil overlap parameter, C[η], correlated well with the zero-shear rate specific viscosities (ηspo) The transition at the critical concentration (C*) occurred at a value of the coil overlap parameter C[η] = 2.7 close to that observed for other galactomannan gums. Storage (G′) and loss (G″) moduli increased with increase in frequency ω), while dynamic shear viscosity η*) decreased. G″ values showed elastic plateaus at high frequencies. The dynamic and steady-shear viscosities at several concentrations followed the empirical Cox-Merz rule.

Abstract: Of five cultures examined, Aspergillus niger NRRL 599 was found to yield the highest activity of polygalacturonase (>25 000 units/kg apple pomace fermented). The enzyme was most active at 40°C and exhibited its optimum activity at pH 4.5. The K m and V max values for polygalacturonic acid were 2.1 mg/mL and 0.12 mmol/L galacturonic acid/min, respectively. The molecular weight of the enzyme as estimated by the gel filtration method was 34 kDa.

Abstract: The thixotropic behaviour of peach pulp at soluble solids concentrations (SS) of 26°, 30° and 34.2° Brix was measured with a cone-and-plate rheometer. Time evolution of shear stress at a shear rate of γ = 1.0s-1 was acceptably represented by first order kinetics. Final, or equilibrium shear stress (τc) was found to increase linearly with SS. Considerable differences among the thixotropic parameters were found when comparing peach and plum pulp samples having practically the same SS, pectin and fiber levels. Scanning electron micrographs showed that differences in thixotropic behaviour could be attributed to differences in the microscopic structure of pulps.

Abstract: Physicochemical and structural properties as well as proneness to hardening were assessed in normal (Mayocoba) and slow (Flor de Mayo) cooking varieties of beans. Storage and chemical procedures were used for determination of the hardening of both samples. Normal and slow cooking varieties had cooking times of 58 and 90 min, respectively. During storage under high temperature and humidity the normal variety exhibited a four-fold increase in cooking time while that of the slow cooker increased nine-fold. Chemical hardening caused an increase in cooking time of 3.4- and 5.7-fold for normal and slow beans, respectively. The former had lower percentage and thinner seed coat, and higher water absorption in the whole seed and seed coat, but not in the cotyledons, as compared to the latter. Chemical analysis demonstrated a much lower tannin content in fresh and hardened seed coats and cotyledons of the normal cooker, but more phytic acid content in cotyledons than in the slow. In fresh and hardened states the normal cooking variety had lower gelatinization and protein denaturation temperatures and enthalpies than the slow. SEM revealed important structural differences between both varieties and conditions. These characteristics may be used as identifying features linked to hardening proneness.