Showing papers in "Lwt - Food Science and Technology in 1997"
TL;DR: In this paper, the reaction mechanisms of three antioxidants are proposed in order to explain experimental results obtained from a kinetic study using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) method, previously adapted in our laboratory.
Abstract: The reaction mechanisms of three antioxidants are proposed in order to explain experimental results obtained from a kinetic study using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH . ) method, previously adapted in our laboratory. In its radical form, DPPH . shows an absorbance maximum at 515 nm which disappears upon reduction by an antiradical compound. BHT, a synthetic antioxidant, slowly reacts with DPPH . reaching a steady state within 5 h. This 2.8-stoichiometric complete reaction follows a 1.5-order with respect to DPPH . and 0.5 to BHT. The kinetic rate constant, k, is estimated to be 5.0 L/(mol·s) at 20 °C and the energy of activation, Ea , is equal to 35 kJ/mol in methanol. Eugenol reacts with DPPH . reaching a steady state within 2 h. This 1.9-stoichiometric reaction follows a 2-order with respect to both DPPH . and eugenol, k and Ea are estimated to be 5.4 × 10 10 L 3 /(mol 3 ·s) at 20 °C and 30 kJ/mol, respectively. The eugenol mechanism may involve a dimerization between two phenoxyl radicals. The reaction with isoeugenol is rapid and reversible, with a stoichiometry of 1.1. It is first order with respect to isoeugenol with k (direct reaction) equal to 8.9 × 10 −2 s −1 at 10 °C. This reaction is consistent with a pseudo-monomolecular mechanism.
1,126 citations
Abstract: Edible coatings can improve the quality of fresh, frozen, and processed meat, poultry, and seafood products by retarding moisture loss, reducing lipid oxidation and discoloration, enhancing product appearance in retail packages by eliminating dripping, sealing in volatile flavors, functioning as carriers of food additives such as antimicrobial and antioxidant agents, and reducing oil uptake by battered and breaded products during frying. This paper reviews the application of various types of lipid-, polysaccharide-, and protein-based edible coatings, as well as multicomponent edible coating systems, on meats, poultry, and seafoods.
461 citations
TL;DR: In this paper, the antioxidant properties of coffee were studied in relation to roasting degree and the extent of the chain-breaking activity and oxygen scavenging properties of Maillard reaction products contained in coffee brews were evaluated.
Abstract: The antioxidant properties of coffee were studied in relation to roasting degree. In particular, the extent of the chain-breaking activity and oxygen scavenging properties of Maillard reaction products contained in coffee brews were evaluated. Samples showed very high chain-breaking and oxygen consumption activities, which did not increase linearly with increasing roasting degree. In our experimental conditions, the highest antioxidant properties were found for the medium-dark roasted coffee brews.
283 citations
TL;DR: The nonperoxide antibacterial activity of honey and honey fractions was tested with Staphylococcus aureus and Micrococcus luteus bacterial species as mentioned in this paper.
Abstract: The nonperoxide antibacterial activity of honey and honey fractions was tested with Staphylococcus aureus and Micrococcus luteus bacterial species. Antibacterial activity correlated significantly with the honey acidity but did not correlate with honey pH. There were small differences between the antibacterial activities of different honey types: rhododendron, eucalyptus and orange honeys had a relatively low activity, whereas dandelion, honeydew and rape honeys had a relatively higher activity. These results suggest that a part of the antibacterial activity might be of plant origin. However, the antibacterial activity of sugar-adulterated honeys was the same as that of control honeydew honeys produced in the same apiary suggesting that the major part of the antibacterial activity of honeydew honey is of bee origin. Ten different honeys were fractionated into four fractions using column chromatography or vacuum distillation: acidic; basic; nonvolatile, nonpolar; and volatile. The antibacterial activity of the different fractions tested was: acids > bases = nonpolar, nonvolatiles > volatiles. This order was the same using either Staph. aureus or Micrococcus luteus as test strains. An exception was manuka honey from New Zealand where almost the entire activity was found in the acidic fraction.
235 citations
TL;DR: In this paper, the authors describe recent achievements in the use of BSA, casein, gelatin and other natural occurring macromolecules together with monomeric-amphiphilic molecules for possible future applications in food systems.
Abstract: Multiple emulsions are complex systems of emulsion within an emulsion, where the droplets of the dispersed phase themselves contain even smaller dispersed droplets. The two major types are water-in-oil-in-water (W/O/W) and oil-in-water-in-oil (O/W/O) double emulsions. Double emulsions are unstable thermodynamic systems, which tend to cream, flocculate and coalesce. Much effort has been made to develop methods of ‘better sealing’ in the inner and outer interfaces and to reduce the droplet size of the emulsion. In addition, dissolved or dispersed compounds in the inner phase of double emulsions tend to be released to the outer phase primarily via a reverse micellar transport (which is diffusion controlled) or through the thin lamellae of a surfactant phase migrating to the outer phase via the outer interface. It is difficult to control the release of the solutes unless macromolecules are used to improve stabilization (steric stabilization) forming a rigid surfactant–polymer complex at the interfaces. The text will describe recent achievements in the use of BSA, casein, gelatin and other natural occurring macromolecules together with monomeric–amphiphilic molecules for possible future applications in food systems.
191 citations
TL;DR: In this article, the effectiveness in moisture retention and reduction of fat uptake of different edible coatings on a fat-free starchy product was determined, and a reduction of 14.9%, 21.9% and 31.1% in moisture loss from the product was observed for samples coated with CZ, HPMC and MC films, respectively.
Abstract: The effectiveness in moisture retention and reduction of fat uptake of different edible coatings on a fat-free starchy product was determined. Mashed potato balls of 47 mm diameter were used as model food system. Samples were coated with corn zein (CZ), hydroxypropyl methyl cellulose (HPMC) or methyl cellulose (MC) film-forming solutions. Uncoated samples were used as control. Compared to the control, a reduction of 14.9%, 21.9% and 31.1% in moisture loss from the product was observed for samples coated with CZ, HPMC and MC films, respectively. Similarly, a reduction of 59.0%, 61.4% and 83.6% in fat uptake by the product was observed for samples coated with CZ, HPMC and MC films, respectively. Based on the overall performance in reducing moisture loss and fat uptake, MC exhibited the most significant barrier properties.
164 citations
TL;DR: The interfacial activity was surprisingly better than other galactomannans (interfacial tension was reduced to 2 mN/m in vegetable oils) which led to the formation of oil-in-water emulsions with small droplet size (2–3 μm) and long-term stability.
Abstract: Fenugreek gum was extracted from fenugreek seeds and evaluated for its surface activity. This unique galactomannan has a mannose backbone grafted with galactose units at an average ratio of one. The purified fenugreek gum was found to reduce surface tension to values lower than guar gum (42 and 55 mN/m, respectively). The interfacial activity was surprisingly better than other galactomannans (interfacial tension was reduced to 2 mN/m in vegetable oils) which led to the formation of oil-in-water emulsions with small droplet size (2–3 μm) and long-term stability. The fenugreek gum was found to adsorb (or ‘precipitate’) on the oil interface forming a relatively thick interfacial film. The emulsions are more stable than any equivalent emulsions stabilized by other galactomannan gums. No flocculation was observed in emulsions stabilized with fenugreek concentrations sufficient for a good coverage of the oil interface as expressed by the coverage index (Rc) correlated to the gum/oil weight ratio (Rc>12).
151 citations
TL;DR: In this article, a multi-component model was used to analyse the proton relaxation curves, from which water in the bread crumb samples was classified into three categories, each of which had a distinct relaxation time (T2) or molecular mobility.
Abstract: The mobility of water in bread stored at 5 and 22 °C was studied using nuclear magnetic resonance (NMR) relaxation techniques. A multi-component model was used to analyse the proton relaxation curves, from which water in the bread crumb samples was classified into three categories, each of which had a distinct relaxation time (T2) or molecular mobility. The changes in crumb firmness, T2and proton intensity (A) of the three categories of water in the crumb were monitored during storage. It was found that several NMR parameters correlated with the firming process in the bread crumb (1), and could be related to macroscopic and microscopic migration of water during staling.
145 citations
TL;DR: This paper examined the formation of different types of chemical bonding in sardine gels made with added proteins (egg white, soy, casein, gluten) at various temperatures, and possible interactions between myofibrillar and nonmuscle proteins in the gel network.
Abstract: The present work examines the formation of different types of chemical bonding in sardine gels made with added proteins (egg white, soy, casein, gluten) at various temperatures, and possible interactions between myofibrillar and nonmuscle proteins in the gel network. The contribution of ionic and hydrogen bonds to thermal aggregation was not found to be decisive. Hydrophobic interactions in gels with egg white were significantly lower than in gels with other nonmuscle proteins. In gels with casein this protein was found to be largely nonspecifically associated with the myofibrillar proteins at high temperatures. The insolubility of the gluten proteins made it difficult to elucidate a possible interaction with the myofibrillar proteins.
136 citations
TL;DR: In this article, a split-plot experiment was conducted to investigate four levels of amylose in starch (main plots) with four levels in whey protein concentrate (WPC) blends (subplots).
Abstract: Use as a minor component in corn starch extrudates may provide an outlet for underutilized whey protein concentrate (WPC). Several physico-chemical and functional properties of corn starch–WPC extrudates were determined in this study. This information can be used for process scaling-up purposes and for tailoring such extrudates to specific applications. Blends of whey protein concentrate and corn starch were extrusion-cooked with a co-rotating intermeshing twin-screw extruder at 220 g/kg moisture content, 140 rpm screw speed and 140 °C barrel temperature. A split-plot experiment was conducted to investigate four levels of amylose in starch (main plots) with four levels of WPC in WPC–corn starch blends (sub-plots). The design was a randomized complete block with the three replications being three different WPC sources. Studied ranges were 0, 250, 500 and 700 g/kg for amylose and 0, 100, 200 and 300 g/kg for WPC. Measured properties were shear strength (51.4 to 361 kPa), radial expansion ratio (4.32 to 13.1), specific mechanical energy (SME) (240 to 383 J/kg), water absorption index (WAI) (1.98 to 8.57), % water solubility index (% WSI) (9.51 to 67.6%), total color difference (8.08 to 35.9) and % apparent amylose content (0–66%) of extrudates. The WPC source affected several extrudate properties. Data were modeled with polynomial regression. Waxy starch differed from amylose starches in terms of % WSI, WAI, and SME. Significant interactions between levels of amylose and WPC were found for radial expansion ratio, total color change and apparent amylose content. This suggested the presence of a physico-chemical interaction between amylose and WPC.
126 citations
TL;DR: In this paper, a 4-d period, the peroxide value in corn and soybean oils reached 13·0 and 8·2 in the presence of rosemary extract and butylated hydroxy toluene (BHT), respectively.
Abstract: Autoxidation of corn and soybean oils was prevented in the presence of 0·1 g/kg rosemary(Rosemarinus officinalis)extract and butylated hydroxy toluene (BHT). At the end of a 4-d period, the peroxide value in corn oil reached 13·0 and 8·2 in the presence of rosemary extract and BHT, respectively. For soybean oil, the peroxide value was found to be 10·0 and 6·6 in the presence of rosemary extract and BHT, respectively. Rosemary extract and BHT, when added as mixtures of 75:25, 50:50 and 25:75 had a synergistic effect on preventing oxidation of soybean oil. Superoxide radicals (O2.−) were generated by phenazine methosulphate-NADH system and rosemary extract was found to scavenge O2.−in a concentration-dependent manner. The antioxidative effect observed is believed to be partly due to this radical scavenger activity.
TL;DR: In this paper, protein hydrolysates from dogfish (Squalus acanthias ) were produced enzymatically using a bacterial endopeptidase, and they were compared with those of the product from autolytic degradation (endogenous enzymes), and those of freeze-dried muscle.
Abstract: Fish protein hydrolysates from dogfish ( Squalus acanthias ) were produced enzymatically using a bacterial endopeptidase. Protein hydrolysates of different degrees of proteolysis (6.5, 13.0 and 18.8% hydrolysis) were obtained by varying the time of hydrolysis. Physical and functional properties, including the rheological characteristics of aqueous dispersions of the protein hydrolysates, were compared with those of the product from autolytic degradation (endogenous enzymes), and those of freeze-dried muscle. Enzymatic modification was responsible for marked changes in the protein functionality. Although the extent of hydrolysis influenced the values of functional properties, those of samples at 6.5 and 18.8% hydrolysis were not significantly different in most cases.
TL;DR: In this paper, the authors evaluated the pressure sensitivities of the kinetic parameters based on the Arrhenius-type volume model and the conventional thermal death time-type model for ultra high pressure pasteurization requirements of milk.
Abstract: This study was carried out to evaluate the ultra high pressure (UHP) pasteurization requirements of milk. Fresh raw milk was subjected to UHP treatment at selected pressures (200–400 MPa) for various holding times (5 to 120 min), and kinetic parameters (rate constant, k and decimal reduction time, D) were evaluated, based on the first order rate model, for the pressure destruction of microorganisms, inactivation of alkaline phosphatase and changes in colour and viscosity. The pressure sensitivities of the kinetic parameters were evaluated based on the Arrhenius-type volume model and the conventional thermal death time-type model. All kinetic behaviours studied were well described by the first order model ( R 2 > 0.90). As expected, higher pressures resulted in higher rates of microbial destruction, enzyme inactivation as well as colour and flavour changes as indicated by the associated lower D values (and higher k values). Further, the rate of microbial destruction was much more rapid than enzyme inactivation or colour and viscosity changes. The evaluated Arrhenius volume change of activation (ΔV ≠ ) for microorganisms, viscosity, alkaline phosphatase and colour were −3.35, −1.41, −1.39 and −1.054 × 10 −5 m 3 mol −1 , respectively. The pressure z values (z p ) for the same variables were 168, 398, 404 and 532 MPa, respectively. Milk subjected to a microbial 4D UHP process at 350 MPa had a shelf-life of 25 d at 0 °C, 18 d at 5 °C and 12 d at 10 °C.
TL;DR: In this article, the effect of fat type (poultry fat and beef tallow), fat content (0 −75 g/kg), and processing conditions (initial water content 160 −200 g/ kg; screw speed 200 −400 rpm) on the degree of starch gelatinization of extruded, dry pet food was investigated.
Abstract: Effect of fat type (poultry fat and beef tallow), fat content (0–75 g/kg) and processing conditions (initial water content 160–200 g/kg; screw speed 200–400 rpm) on the degree of starch gelatinization of extruded, dry pet food was investigated. Fat content had the most prominent influence on starch gelatinization of the samples. Increasing the fat content significantly decreased the degree of starch gelatinization of the extrudates. Addition of beef tallow resulted in a lower degree of starch gelatinization as compared to poultry fat. Increasing the initial moisture decreased the degree of starch gelatinization of the extrudates. However, the effect was not very significant within the range studied. Interactive effects of screw speed and fat content on starch gelatinization of dry pet foods were observed.
TL;DR: In this paper, the microflora of kefir grains of household origin was isolated and identified, at least two lactococci, two lactobacilli, two yeast and one mould were detected.
Abstract: The microflora of kefir grains of household origin was isolated and identified. At least two lactococci, two lactobacilli, two yeast and one mould were detected. Different methods for kefir grain preservation were studied. Metabolic activity of grains preserved frozen at −20 °C and −80 °C and grains stored at 4 °C was evaluated. Grains stored at −20 °C and −80 °C maintained their microflora and increased their weights at a rate comparable to that found with nonstored grains. Fermented milk obtained with the grains stored at −20 °C and −80 °C showed the same microflora, rheological behaviour, acidity and carbon dioxide content as fermented milk obtained with nonstored grains. Grains stored at 4 °C did not increase their weight and the product obtained did not have the acidity and viscosity of the standard product. Storage at −20 °C is a good method to preserve kefir grains for household manufacture of fermented milk.
TL;DR: Methods available for myoinositol phosphate measurement, effects of processing and role of myoinosine phosphates in human nutrition, including possible anticancer functions and other positive effects, will be discussed in contrast to the detrimental effects of myoisofiltration on mineral element bioavailability.
Abstract: Methods available for myoinositol phosphate measurement, effects of processing and role of myoinositol phosphates in human nutrition, including possible anticancer functions and other positive effects, will be discussed in contrast to the detrimental effects of myoinositol phosphates on mineral element bioavailability. The phytic acid content in diets will also be discussed.
TL;DR: Damaged organelles and lack of ribosomes suggests cytological disruption as an alternative inactivation mechanism to the accepted electroporation theory.
Abstract: Saccharomyces cerevisiae(ATCC 16664) inoculated into commercial heat sterilized apple juice was treated with high intensity (40 kV/cm) pulsed electric fields (PEF). Transmission electron microscopy (TEM) observations of PEF treatedS. cerevisiaecells provided little evidence to support the electroporation inactivation theory as the major mode of yeast inactivation. TEM micrographs of PEF treatedS. cerevisiaefrom apple juice exhibited frequent disruption of yeast cellular organelles and almost total absence of ribosome bodies. Damaged organelles and lack of ribosomes suggests cytological disruption as an alternative inactivation mechanism to the accepted electroporation theory. Naturally occurring bud scars formed through propagation of daughter yeast cells from mother yeast cells were differentiated from PEF induced scars with TEM observations.
TL;DR: In this article, the authors investigated the inactivation of Lactobacillus sp. from kimchi by high pressure carbon dioxide in a batch system and found that cell death resulted from the lowered intracellular pH due to penetration of CO 2, rather than physical rupture of cell walls due to the high pressure.
Abstract: Inactivation of Lactobacillus sp. from kimchi by high pressure carbon dioxide was investigated in a batch system. Inactivation rates increased with increasing pressure, temperature and exposure time, and with decreasing working volume ratio. Microbial reduction of 5 log cycles was observed within 200 min under a CO 2 pressure of 70 kg/cm 2 at 30 °C. It was suggested that cell death resulted from the lowered intracellular pH due to penetration of CO 2 , rather than physical rupture of cell walls due to the high pressure of CO 2 . The experimental results suggested that high pressure CO 2 treatment could be used as a potential nonthermal technique for kimchi preservation.
TL;DR: In this article, a common methodology to characterize smell, aroma, taste and trigeminal sensations of hard and semi-hard cheeses was determined, and an evaluation scale for the different characteristics was defined.
Abstract: Resume A Guide to the Sensory Evaluation of Smell, Aroma and Taste of Hard and Semi-hard Cheeses Within a European research programme (AIR-CT-94-2039), a group of researchers undertaking sensory analysis of cheese applied itself to standardizing panel training methods. A common methodology to characterize smell, aroma, taste and trigeminal sensations, that is to say olfactory and gustative properties of hard and semi-hard cheeses was determined. These properties were evaluated on five Protected Designation of Origin cheeses (PDO) by panels working in four countries. Without neglecting the importance of texture on aroma perception, the group defined an evaluation scale for the different characteristics. Odours and aromas were classified in odour and aroma families that were tested by the panels. A cheese aroma wheel is proposed. Along with the former methodology for sensory evaluation of texture published in 1993 the present work completes the methodology for the sensory characterization of hard and semi-hard cheeses made from cow milk. Dans le cadre d'un programme europeeen (AIR-CT94-2039 et COST95), un groupe de responsables de l'analyse sensorielle des fromages a travaille sur l'harmonisation des methodes pour entrainer des jurys. Ce travail a conduit a l'elaboration d'une methodologie commune pour caracteriser des odeurs, les aromes, les saveurs et les sensations trigeminales, c'est-a-dire les proprietes olfacto-gustatives des fromages a a pâte dure et semi-dure. Ces proprietes ont ete evaluees sur cinq fromages a Appellation d'Origine Protegee (AOP) par des jurys travaillant dans quatre pays differents. Sans negliger l'importance de la texture sur la perception des aromes, le groupe s'est defini un ordre pour l'evaluation des differentes caracteristiques. Les odeurs et les aromes ont ete classes dans des familles d'odeur et d'arome testees par les jurys. Une roue des aromes des fromages est proposee. Tous les descripteurs sont precises par des references. La methodologie proposee permet aussi bien de decrire que de quantifier les caracteristiques olfacto-gustatives des fromages. Finalement, avec la pecedente methodologie mise au point pour l'evaluation de la texture en 1993, ce travail forme un ensemble pour la caracterisation sensorielle des fromages a pâte dure et semi-dure au lait de vache.
TL;DR: In this article, chemical composition (oil, protein, carbohydrate, phenolic acids and cyanogenic glycosides) and physical properties (water hydration capacity, viscosity and protein solubility) were determined in whole and dehulled seeds of seven flax cultivars.
Abstract: Chemical composition (oil, protein, carbohydrate, phenolic acids and cyanogenic glycosides) and physical properties (water hydration capacity, viscosity and protein solubility) were determined in whole and dehulled seeds of seven flax cultivars. Dehulling of seeds by the Tangential Abrasive Dehulling Device significantly increased the concentration of oil and protein and decreased the carbohydrate content in dehulled flaxseed irrespective of cultivars. The hull fraction had the highest carbohydrate and palmitic acid contents and the lowest concentration of stearic and oleic acid compared to the whole and dehulled seeds. Significant changes in phenolic acids and cyanogenic compounds observed upon dehulling were due to differences among cultivars. Abrasive dehulling had no significant effect on protein solubility. Reduction in water hydration capacity and viscosity of flaxseed was related to the amount of hull removed upon dehulling.
TL;DR: In this article, the inactivation of β-galactosidase was investigated in dried matrices of poly(vinyl)pyrrolidone (PVP), maltodextrin and trehalose.
Abstract: Thermal inactivation of β-galactosidase was investigated in dried matrices of poly(vinyl)pyrrolidone (PVP), maltodextrin and trehalose. Significant lactase inactivation was observed in the polymeric matrices kept well below their glass transition temperature (T g ). The stability of the enzyme in the anhydrous glassy matrices of maltodextrin and PVPs heated at 70 °C was directly related to their T g ; i.e. systems with higher glass transition temperature afforded better thermal protection of lactase. However, the stability of lactase in the heated trehalose matrix deviated from this behaviour since enzyme stability was higher than expected on the basis of the results obtained with polymeric matrices. In systems in which the trehalose matrix was rehumidified to conditions which allowed a high proportion of trehalose to crystallize, the enzyme was rapidly inactivated upon heating. Addition of maltodextrin to trehalose matrix provided enhanced protection to the enzyme, and this was probably due to delayed trehalose crystal formation.
TL;DR: In this paper, the pectin methylesterase (PME) in single-strength orange juice was evaluated under batch mode heating conditions and the results indicated that the enzyme inactivation data to be characterized by the following: microwave: D 60 = 7·37 s (z = 13·4 °C); thermal:D 60 = 154 s (Z = 17·6 °C).
Abstract: Thermal and microwave inactivation kinetics of pectin methylesterase (PME) in single-strength orange juice were evaluated under batch mode heating conditions. For thermal inactivation, aliquots of orange juice sealed in glass ampoules were subjected to conventional heat treatments in a well agitated water-bath for various times at selected temperatures (60, 70, 80, 85 and 90 °C). For microwave inactivation, different amounts of orange juice in a glass beaker (100 mL capacity) were heated in a microwave oven for preselected time intervals to yield the desired final temperatures (50, 55, 60 and 65 °C). Heating times under both modes were corrected to accommodate only their effective portions for kinetic data handling. Based on residual PME activities and first order rate of inactivation kinetics, kinetic parameters were evaluated. Results indicated the enzyme inactivation data to be characterized by the following: microwave: D 60 = 7·37 s (z = 13·4 °C); thermal: D 60 = 154 s (z = 17·6 °C). Thus, the PME inactivation in orange juice was significantly faster in the microwave heating mode than in conventional thermal heating mode indicating some contributory nonthermal effects under the microwave heating conditions. Thermal inactivation also indicated the presence of two fractions, one more heat sensitive than the other, while only one fraction was apparent with microwave heating. Inactivation kinetics were also dependent on pH and soluble solids content of orange juice. PME was more sensitive to thermal inactivation at lower pH and higher soluble solids concentration.
TL;DR: The inhibitory activity in the two Lactobacilli cell-free supernatants was shown to be unrelated to the production of lactic acid or hydrogen peroxide, and was found to be sensitive to proteolytic enzymes and to high temperature (100 °C).
Abstract: Lactic acid bacteria isolated from dairy products, vegetables and fruits were screened for their antifungal and antimycotoxigenic activities. From 420 isolates tested, four isolates were found to be inhibitory to four Penicillium species. Two of the lactic acid bacteria isolates showed the largest inhibitory activity against Penicillum citrinum and Penicillium expansum . The two isolates were identified as Lactobacillus casei species. Production of patulin and citrinin was also inhibited in the presence of the Lactobacilli supernatants. The inhibitory activity in the two Lactobacilli cell-free supernatants was shown to be unrelated to the production of lactic acid or hydrogen peroxide, and was found to be sensitive to proteolytic enzymes and to high temperature (100 °C). The antimycotoxigenic activity was not affected by the addition of glucose used by Lactobacilli species during incubation.
TL;DR: In this article, the acid anhydride form of sorbic acid was incorporated into polyethylene films and the inhibitory effect of the films against fungal growth was also demonstrated.
Abstract: Sorbic anhydride, the acid anhydride form of sorbic acid, was incorporated into polyethylene films. The incorporation was confirmed by FT-IR spectra and by recovery of sorbic acid from pH 3.5 buffer and potato dextrose agar after the resulting films were suspended in the buffer solutions or contacted with the media. The inhibitory effect of the films against fungal growth was also demonstrated.
TL;DR: Germination conditions for a high amylose rice cultivar were optimised using response surface methodology and values predicted at optimum conditions by the response surface model for malt loss, viscosity, amylase activity, yield and thiamin content were experimentally tested.
Abstract: Germination conditions for a high amylose rice cultivar were optimised using response surface methodology Germination time and temperature significantly affected the amylase activity and thiamin content of the subsequent flour All germination conditions investigated significantly affected the malting loss while the change in cold paste viscosity was significantly influenced by steeping time, germination time and temperature The yield or recovery was significantly affected by germination time only Protein content was not altered significantly by the germination conditions investigated Optimum germination conditions for high amylose rice were: steeping time 24 h at 25 °C or 16 h at 35 °C, germination time 3 d, germination temperature 30 °C Values predicted at optimum conditions by the response surface model for malt loss, viscosity, amylase activity, yield and thiamin content were experimentally tested and close agreement between experimental and predicted values was observed
TL;DR: In this article, the quality attributes of filleted rainbow trout and Baltic herring in over-wrap packages (polystyrene or wood fibre), vacuum packages and gas packages (35% CO 2 + 32·5% Ar + 32 ·5% N 2 N 2 ) stored at 2 °C were compared.
Abstract: The quality attributes of filleted rainbow trout and Baltic herring in over-wrap packages (polystyrene or wood fibre), vacuum packages and gas packages (35% CO 2 + 32·5% Ar + 32·5% N 2 , 35% CO 2 + 65% Ar, or 40% CO 2 + 60% N 2 ) stored at 2 °C were compared. Mesophilic bacteria grew most quickly in over-wrap packed fillets and most slowly in vacuum and gas packed fillets. Coliform bacteria grew faster in over-wrap and vacuum packed fish than in gas packed fish. Over-wrapped herring fillets had the least drip formation during storage, whereas gas-packed herring had the greatest drip. Drip was very small in trout fillets in all package types. The appearance of herring was evaluated as worse in vacuum and gas packages due to the excessive drip formed. The odour of trout packed in a wood fibre package was evaluated as slightly poor at the very beginning of the storage due to the very strong odour of the package, which masked the odour of the fish. The sensory quality of both fillets deteriorated faster in over-wrap and vacuum packages than in gas packages. The sensory quality of trout and herring in the three types of gas packages was quite similar. Argon in the gas mixture did not increase the shelf-life of fillets.
TL;DR: In this paper, two grape varieties with coloured berries grown in a collection vineyard in Murcia were sampled by analysing their pigment content and external color and quantified with the aid of a reversed-phase column and a photodiode detector.
Abstract: Thirty-two grape varieties with coloured berries grown in a collection vineyard in Murcia were sampled by analysing their pigment content and external colour. Anthocyanins were separated by HPLC and quantified with the aid of a reversed-phase column and a photodiode detector. Using the content of individual anthocyanins, several indices were calculated and linked to hydroxylation, methylation and the esterification processes of the biosynthetic pathway. These colour parameters and indices were correlated by means of a principal components analysis. A cluster analysis split the 32 varieties into nine groups. The similarity of anthocyanin profiles in the varieties within each group enables the use of this technique for chemotaxonomic purposes.
TL;DR: In this paper, high hydrostatic pressure inactivation kinetics of Zygosaccharomyces bailii in food model systems of pH 35 and water activities (a w ) of 098 and 095 were evaluated at 21 °C and pressures from 241 to 517 MPa.
Abstract: High hydrostatic pressure inactivation kinetics of Zygosaccharomyces bailii in food model systems of pH 35 and water activities ( a w ) of 098 and 095 were evaluated at 21 °C and pressures from 241 to 517 MPa The come-up time to reach a pressure exerts an important effect on the survival fraction of Z bailii Yeast inactivation followed first order reaction kinetics, with inactivation rates and decimal reduction times that varied from 0176 to 2833 min −1 and from 131 to 08 min, respectively The pressure dependence of the yeast inactivation rates can be described by the apparent activation volume and by a ‘pressure z value’, revealing in both cases a greater pressure dependence for systems with a w 098
TL;DR: In this paper, the authors assessed the use of high pressure CO 2 treatment to inhibit Staphylococcus aureus in broth and raw cow's milk at 25 °C.
Abstract: Studies were carried out to assess the use of high pressure CO 2 treatment to inhibit Staphylococcus aureus in broth and raw cow's milk at 25 °C. Two phases in the survival curves were observed. The early stage was characterized by a slow rate of decrease in number of S. aureus ; this rate increased sharply at the later stage. Staphylococcus aureus suspended in broth was completely inactivated after CO 2 treatment at 7 MPa for 100 min and 8 MPa for 60 min. The sterilization effects of CO 2 on both S. aureus and aerobic bacteria were observed at 14.6 MPa for 5 h and 9 MPa for 2 h in whole and skim milk, respectively. Staphylococcus aureus and aerobic bacteria were more difficult to inactivate when they were suspended in whole milk that may have protected the cell from penetration by CO 2 . Reduction rates of S. aureus and aerobic bacteria were sensitive to pressure, exposure time and the suspending medium.
TL;DR: In this article, the effect of enzymatic modification of wheat flour proteins on their functional properties was evaluated as a function of the degree of hydrolysis (DH), and the authors concluded that 3.8-14.1% DH was sufficient to improve quality parameters of cakes such as volume, moisture and crumb colour.
Abstract: The effect of enzymatic modification of wheat flour proteins on their functional properties was evaluated as a function of the degree of hydrolysis (DH). Soluble protein increased from 7.1 to 53% for 0% to 36.7% DH flour, and viscosity and yield values decreased concomitantly. Emulsion capacity slightly decreased up to 14% DH and then increased. Baummann water and oil absorption capacities and farinograph water absorption had similar trends; they showed a maximum increase at 3.8% DH where Baumann and farinograph absorption values increased by 30%. Limited degree of hydrolysis (3.8–14.1% DH) was sufficient to improve quality parameters of cakes such as volume, moisture and crumb colour. Added protease resulted in pronounced reduction in molecular mass distribution of wheat proteins, especially glutenins. The increase in water soluble protein as hydrolysis proceeded was related to proteins of molecular mass less than 25 kDa. The reduction in viscosity and foam stability was related to the extent of hydrolysis of high molecular mass glutenin protein. The increased Baumann and farinograph water absorption by limited hydrolysis up to 3.8–5.4% DH may be related to increased number of polar sites and flexibility of protein network, without extensive degradation of glutenins.