Higher Breaking Force Research Articles

Hydration kinetics and textural properties of pigeon peas (Cajanus cajan)

Soaking of dry pigeon peas was studied at 27, 45, 60 and 75oC. Water absorbed during soaking was a function of both soaking time and temperature. Soaking at high temperatures increased the hydration rate constant and decreased the soaking time to achieve equilibrium moisture content (EMC)).The activation energy value (Ea) of the hydration process was 12.95kcal/mole. Texturalstudies revealed that the hardness of the grain was a function of the soaking time, temperature of soaking and loading position. The horizontal helium position required a higher breaking force (N) than the vertical helium position after soaking of the grains.

Contribution of protein conformation and intermolecular bonds to fish and pork gelation properties

Changes in protein conformation and intermolecular interactions during gelling were measured to explore the basis for the different gel properties of fish and pork pastes after heat treatment. Raman spectral analysis revealed that, in the unheated pork sample, more tyrosine residues were buried or involved as hydrogen bond donors than in the fish counterpart. Hydrophobic interaction increased and then decreased with increasing temperature, reaching a maximum value at 60 and 70 °C for fish and pork samples, respectively. Formation of disulfide bonds mainly occurred at 70–80 °C for fish, and 50–60 °C for pork samples. Incubation at 4–40 °C induced abundant non-disulfide covalent cross-linking in fish, but not in pork samples. The differences in protein conformation and intermolecular bonds possibly contributed to diverse gelation properties between fish and pork samples. At 40 and 50 °C, the breaking force of fish samples was significantly higher than that of pork. However, higher breaking force was observed in pork samples above 60 °C. Pre-incubation at 40 °C significantly increased the breaking force of the cooked fish sample, but had little effect on the breaking force of the cooked pork sample. In addition, incubating pork paste at 40 °C could decrease the cooking loss of the cooked pork sample.

Physicochemical and gelling properties of short-bodied mackerel ( Rastrelliger brachysoma) protein isolate prepared using alkaline-aided process

This study demonstrated the characteristics and gel properties of short-bodied mackerel ( Rastrelliger brachysoma) surimi prepared by the conventional washing process and protein isolate prepared by alkaline solubilization process without and with prewashing. A decrease in Ca 2+-ATPase activity ( P < 0.05), with changes in the tryptophan fluorescence intensity of natural actomyosin, was observed in protein isolate from alkaline solubilization process. However, higher reactive sulfhydryl (SH) content was found in protein isolate, compared with that in conventional surimi ( P < 0.05). Generally, the higher amounts of lipid and myoglobin in fish mince were removed by using the alkaline-aided process, compared with the conventional process ( P < 0.05). Protein isolate from the alkaline solubilization process formed gels with higher breaking forces than conventional suirmi, especially with 2-step heating (40 °C, 30 min/90 °C, 20 min) ( P < 0.05). The lowest expressible moisture was found in the gel of protein isolate prepared by alkaline solubilization process ( P < 0.05). However, the highest whiteness was found in the conventional surimi gel prepared by 2-step heating ( P < 0.05). Protein isolate prepared by the alkaline solubilization process yielded superior gels compared with the conventional surimi. Therefore, it can be concluded that the gelling properties of surimi or protein isolate are governed by the physicochemical properties of proteins and are affected by processing conditions.

Biochemical and gelling properties of tilapia surimi and protein recovered using an acid-alkaline process

The biochemical and gel properties of tilapia surimi prepared by a conventional washing method and protein isolated using alkaline-acid-aided processes were studied. Solubility and recovery of protein was found to be highest by using a conventional method, followed by an alkaline- and acid-aided process, respectively. Decreases in myoglobin and lipid contents were found in alkaline- or acid-aided process when compared to the conventional process ( p < 0.05). The highest breaking force and deformation of kamaboko and modori gels was found in the gels prepared by the conventional washing method. Higher expressible water and whiteness were found in modori gels when compared to kamaboko gels. TCA-soluble peptide contents of conventional surimi gels were lower than those of acid- and alkaline-recovered protein gels. Degradation of myofibrillar protein was observed in acid-isolated protein. Microstructure of kamaboko gels showed more compact network than in modori gels in both conventional surimi and protein recovered using the pH-shift process.

Properties of Milk Protein Gels Formed by Phosphates

We investigated the properties of gels that were formed by adding emulsifying salts, such as tetrasodium pyrophosphate (TSPP), to reconstituted milk protein concentrate solution. The pH of a 51g/L milk protein concentrate solution was adjusted to 5.8 after adding TSPP. Milk protein concentrate solutions were placed in glass jars and allowed to stand at 25°C for 24h. Gels with the highest breaking force were formed when TSPP was added at a concentration of 6.7mM, whereas no gel was formed when TSPP was added at concentrations of ≤2.9 or ≥10.5mM. Several other phosphate-based emulsifying salts were tested but for these emulsifying salts, gelation only occurred after several days or at greater gelation temperatures. No gelation was observed for trisodium citrate. Gelation induced by TSPP was dependent on pH, and the breaking force of gel was greatest at pH 6.0. Furthermore, when the concentration of milk protein concentrate in solution was increased to 103g/L, the breaking force of the gel increased, and a clearly defined network between caseins could be observed by using confocal scanning laser microscopy. These results suggest that TSPP-induced gelation occurs when the added TSPP acts with calcium as a cross-linking agent between dispersed caseins and when the balance between (a reduced) electrostatic repulsion and (enhanced) attractive (hydrophobic) interactions becomes suitable for aggregation and eventual gelation of casein molecules.

Elucidating Factors Affecting Floatation of Fish Ball

ABSTRACT: Factors affecting floatation of fish ball in water were investigated. The density of threadfin bream (TB) surimi paste significantly decreased (P &lt; 0.05) as moisture content, temperature, or salt concentration increased. The ability of surimi paste to float or sink in water was observed according to changes in density. In gel texture measurement, when surimi was thawed for 1 h before chopping at 5 °C with 2% salt, the highest breaking force and deformation values were obtained. Apparent viscosity of surimi paste decreased as moisture content increased or salt concentration increased, and chopping temperature decreased. Setting gels in salt solution (5 or 10%) significantly reduced (P &lt; 0.05) stickiness, which is the tendency to stick to one another.

On the tensile strength distribution of multiwalled carbon nanotubes

Individual multiwalled carbon nanotubes grown by chemical vapor deposition (CVD) were tensile tested within the chamber of an electron microscope using an atomic force microscope-based technique. Weibull–Poisson statistics could accurately model the nanotube tensile strength data. Weibull shape and scale parameters of 1.7 and 109GPa were obtained. The former reflects a wide variability in strength similar to that observed for high-modulus graphite fibers, while the latter indicates that the irregular CVD-grown tube wall structure requires, in some cases, higher breaking forces than more regular tube wall structures. This apparent strengthening mechanism is most likely caused by an enhanced interaction between the walls of the nanotube.

Combination effects of chicken plasma protein and setting phenomenon on gel properties and cross-linking of bigeye snapper muscle proteins

Effects of chicken plasma protein (CPP) in combination with setting on surimi gel properties and protein cross-linking were investigated. Addition of CPP (0.5g/100g), CaCl2 (10mmole/kg) and 200 units of thrombin/g CPP in combination with setting at 40°C for 30min prior to heating at 90°C for 20min resulted in the highest breaking force and deformation (P<0.05). Regardless of CPP addition, myosin heavy chain (MHC) in surimi proteins and natural actomyosin (NAM) underwent polymerization to some extent in the presence of CaCl2 and thrombin. The cross-linking of MHC in surimi proteins were markedly suppressed by the addition of EGTA and NH4Cl, transglutaminase (TGase) inhibitors. No cross-linking of myosin was observed when CPP, CaCl2 and thrombin were added, even with the prolonged incubation time. The result revealed that CPP showed no cross-linking activity and gel strengthening effect of CPP was attributed to its filler effect and proteolytic inhibitory activity.

Effects of Alkali and Acid Solubilization on Gelation Characteristics of Rockfish Muscle Proteins

ABSTRACT: Solubility of rockfish whole muscle and actomyosin was minimum at pH 5 and gradually increased as the pH was shifted to acidic or alkaline pH. Acidic and alkaline solubilization was followed by isoelectric precipitation induced degradation of myosin heavy chain, resulting in a protein band of about 120 kDa. Both myofibrillar and sarcoplasmic proteins underwent denaturation after acidic and alkaline treatment, exhibiting minimal solubility and absence of endothermic peaks. Acid‐ and alkali‐treated muscle proteins readily aggregated upon heating, showing different dynamic rheological patterns compared with whole muscle and washed mince. Disulfide linkages occurred at a greater extent in gel prepared by alkaline solubilization, resulting in higher breaking force and deformation.

Effect of high‐temperature setting on gelling characteristic of surimi from some tropical fish

SummaryThe effect of setting at 40 °C on the textural properties and the changes in myofibrillar proteins in surimi produced from threadfin bream (Nemipterus bleekeri), bigeye snapper (Priacanthus tayenus), barracuda (Sphyraena jello) and bigeye croaker (Pennahai macrophthalmus) was investigated. An increase in the time of setting generally resulted in higher breaking force and also the deformation of both suwari and kamaboko gels. Maximum increases in gel‐breaking force were obtained in 1 h for threadfin bream, 2 h for bigeye snapper, 1.5 h for barracuda and 3 h for bigeye croaker. Extended setting time caused decreases in breaking force and deformation in all surimi, except that produced from bigeye croaker. Gel strengthening was associated with an increase in non‐disulphide covalent bond formation. Degradation of proteins occurred with prolonged setting. Therefore, setting at 40 °C for an appropriate time is a promising means to improve the gelling property of surimi produced from tropical fish.

Eggshell strength

Eggshell quality was studied in two groups of Shaver hens (300 hens per group) 30 weeks of age. All hens received a basic diet of the same composition with pulverized limestone as a source of calcium. The experimental group received 2 g of granular limestone (particle size 1.1-1.4 mm) per hen per day during one week, adding on the concentrate in the afternoon. Significantly lower deformation (19 m), higher breaking force (4,1 kg) and shell thickness (39, 3 x 0.01 mm) were registered for eggs of experimental group of hens than for eggs of control group (24 m; 3.3 kg 36.5 x 0.01 mm, respectively). The results obtained in our investigation showed possibilities of eggshell strength improvement using 2 g of larger particle size of limestone as additional source of calcium.

Chicken plasma protein affects gelation of surimi from bigeye snapper ( Priacanthus tayenus)

Effect of chicken plasma protein (CPP) at different concentrations on gel properties of grade SA and A bigeye snapper surimi was investigated. Addition of 0.5% CPP in combination with setting at 40 °C for 30 min prior to heating at 90 °C for 20 min resulted in the highest breaking force and deformation ( P<0.05). However, whiteness decreased to some extent. CPP was able to prevent the degradation of surimi proteins as indicated by the decrease in TCA-soluble peptides ( P<0.05). Electrophoretic studies revealed that myosin heavy chain underwent polymerization to a lower extent as CPP concentration increased. Therefore, CPP worked as protease inhibitor rather than protein cross-linker. Microstructure of kamaboko gels, added with 0.5% CPP, had less linkage between protein strands with a coarser fibrillar structure, indicating the interfering effect of CPP on cross-linking of myofibrillar proteins. Thus, at an appropriate amount, CPP possibly worked as a filler in the surimi gel matrix, resulting in gel strengthening.

Effect of medium temperature setting on gelling characteristics of surimi from some tropical fish

Effects of setting at 25 °C on textural properties and cross-linking of myofibrillar proteins in surimi produced from threadfin bream ( Nemipterus bleekeri), bigeye snapper ( Priacanthus tayenus), barracuda ( Sphyraena jello) and bigeye croaker ( Pennahai macrophthalmus) were investigated. Increase in setting time (0–8 h) resulted in a higher breaking force and deformation for all surimi gels tested ( P<0.05). Increased gel strength was associated with increase in non-disulfide bond formation and decreased heavy chain myosin. Proteins underwent degradation during setting; however polymerization occurred to a much higher extent, leading to a strengthened gel matrix. Therefore, setting at 25 °C, for an appropriate time, should be a promising means to improve gelling properties of surimi produced from tropical fish.

Variations of Mature Cotton Fiber Tensile Properties: Association with Seed Position and Fiber Length

Variations in single fiber tensile properties of mature cotton fibers are investigated with respect to their association with seed positions and fiber-length groups within individual locules. Fibers from five varieties representing four cultivated cotton species ( G. herbeceum, G. arboreum, G. hirsutum, and G. barbadense) are included in this study. With the exception of G. arboreum, breaking forces, toughness, and linear density are highly dependent on the seed position in the locule, and the dependence is especially high for G. herbeceum and G. barbadense. Fibers from seeds located closer to the main stem have higher breaking forces and linear densities, indicating their association with the distribution of nutrition resources. The relationships between single fiber tensile properties and fiber lengths vary among these cotton species. Breaking force and tenacity are independent of fiber length for G. barbadense, whereas fiber-length dependence is positive for G. herbeceum and G. arboreum, and there is a negative trend for the Maxxa variety of G. hirsutum. For G. herbeceum and G. arboreum, longer fibers have higher breaking forces, whereas the opposite is true for Maxxa. Single fiber breaking elongation decreases with increasing fiber length for all except G. barbadense. Overall variations of single fiber tensile properties are associated more strongly with the seed position in the locule than with the fiber length.

Gelation Enhancement of Soy Protein Isolate using the Maillard Reaction and High Temperatures

ABSTRACTSoy protein isolate gels prepared by autoclaving solutions in the presence of xylose of glucono‐δ‐lactone (GDL), were compared. In both cases, the pH decreased from neutral to pH 5.5 during gel formation. In the xylose systems, this pH decrease was a consequence of the Maillard reaction. The Maillard gels showed less syneresis, had a higher breaking force and were more elastic, as determined by stress relaxation, then the GDL gels. The differences were attributed to formation of additional covalent crosslinks due to the Maillard reaction, as evidenced by greatly reduced solubility in sodium dodecyl sulfate +β‐mercaptoethanol.

Factors affecting the development of ‘finger drop’ in bananas after ripening

SummaryA simple mechanical method has been developed to measure the force required to break banana fruit peel in the region of the pedicel. Values obtained for peel breaking force correlate well with measured differences in susceptibility to ‘finger drop’.Longer periods for fruit ripening, obtained by a reduction of the conventional ripening temperature, favour maintenance of a high peel breaking force and extend the shelf life of ripe fruit but reduce the degree of coloration. Finger drop in bananas of tetraploid clones, which are highly susceptible to its development, could be minimized by ripening at temperatures about 2°C lower than those optimal for ‘Valery’, a major commercial triploid cultivar.The peel breaking forces of different tetraploid clones were compared under controlled ripening and shelf life conditions and several clones with significantly reduced susceptibilities to finger drop were identified. Clones with a low susceptibility to finger drop were generally also characterized by a long pre‐climacteric period.