The effect of compressibility,loading position and probe shape on the rupture probability of tomato fruits

In this study, factors affecting the rupture probability of tomato fruits were investigated. The experiments were carried out at five compressibility levels (4%, 8%, 12%, 16% and 20%), four loading positions and two probe shapes. The fruit size, shape and mass did not have a significant effect on the rupture probability. The compressibility was the most important independent variable affecting the rupture probability of tomato fruits in the model. The rupture probability of quadrilocular tomato fruit loaded from the cross-wall tissue was the highest, and the odds of being ruptured was 14.5 times higher for quadrilocular tomato fruit loaded from the cross-wall tissue compared to the locular tissue. The curved probe was much more sensitive than the plate probe for rupturing of tomato fruits during the compression tests. It is clear that these investigated factors need to be considered carefully in design and control of tomato harvesting equipment.     

Moisture-dependent properties of barnyard millet grain and kernel

The geometric mean diameter, sphericity, grain surface area, 1000 grain mass, true density (toluene displacement method), terminal velocity, dynamic angle of repose, coefficient of internal friction, coefficient of static friction at different surfaces (sun mica, canvas and mild steel surfaces), specific deformation and rupture energy of the grain were found to increase 12.21%, 4.79%, 30.47%, 30.75%, 6.74%, 32.99%, 127.05%, 60%, 18.57%, 34–67%, 69.2% and 88.87% respectively at increase of moisture content from 0.065 to 0.265 kg kg⁻¹ dry matter. However, true density (proximate composition method), bulk density, interstices and rupture force of grain was found to be decrease 8.64%, 20.1%, 86.49% and 21.17% respectively at increase of moisture content. Similar trend was observed for barnyard kernel also. True density (toluene displacement method) was found lower as compared to true density (proximate composition method) at all experimental moisture range indicated that the presence of void space inside the grain and kernel.     

Phenolics, betacyanins and antioxidant activity in Opuntia joconostle fruits

Sour prickly pears (xoconostles) are fruits from Opuntia joconostle cactus, which are cultivated in the central Mexico area. Phenolic and pigment content in various parts of O. joconostle fruits were analyzed. The antioxidant activity of a methanolic extraction and different semi-purified fractions were also evaluated by the DPPH⁺ method. Xoconostle fruits were obtained from a commercial orchard in Mexico State. Fruits were analyzed as whole fruit and each fruit part including pericarp, mesocarp and endocarp. Samples were homogenized and kept at 4 °C until sample preparation. Total phenolic content and total flavonoid content varied among the different parts of the fruit. The highest amount of phenolic compounds and total flavonoids content were found in pericarp 2.07 mg gallic acid equivalents (GAE)/g fresh weight (FW) and 0.46 mg(+)-catechin equivalents (CE)/g FW respectively. Seven phenolics were identified as protocatechuic, 4-hydroxybenzoic, caffeic, vanillic and syringic acids, rutin, and quercetin. The color of the fruit parts was mainly due to the presence of betacyanins. The betacyanin concentration was higher in the endocarp (23.03 mg betanin equivalents/100 g fresh weight) than in the pericarp and mesocarp. Betacyanins were identified by HPLC-PDA-MS as betanin, isobetanin, betanidin, isobetanidin, and phyllocactin. Methanolic extracts and semi-purified fractions A (phenolics and flavonols) and B (betacyanins) of xoconostle showed high antioxidant activity mainly in the pericarp. These results suggest that xoconostle is a rich source of antioxidant compounds such as phenolic compounds and betacyanins.     

Some properties of corn grains and their flours I: Physicochemical,functional and chapati-making properties of flours

The variability in physical (1000 kernel weight and bulk density) and mechanical (rupture force) properties of grains from different Indian corn varieties (African tall, Ageti, Early composite, Girja, Navjot, Parbhat, Partap, Pb sathi and Vijay) were studied. The functional (colour, gelatinization, retrogradation and pasting) and chapati-making properties of flours milled from corn varieties were evaluated. African tall flour showed the highest enthalpy of gelatinization (ΔH_gel), peak-, trough-, breakdown-, final-, and setback viscosities, and L^∗ (84.4) value and resulted in chapaties with higher extensibility (5.76 mm) and of light colour. African tall flour, with the lowest protein content, showed the lowest grain rupture force. Amylose content and hardness of starch gel from African tall were found to be the lowest among all corn varieties. Girja flour, with the lowest transition temperatures and ΔH_gel, showed the lowest extensibility of chapaties made from it. Pearson correlations between physical and textural properties of corn grains and the functional properties of their flours were established. Rupture force of corn grain and protein content of flour showed a negative correlation with peak viscosity of flour (r = −0.917, and −0.863, p < 0.01). The protein content of flours was negatively correlated with L^∗ (r = −0.759, p < 0.01) value and positively with b^∗ (r = 0.635, p < 0.01) value. Pasting temperature of flours showed a significant negative correlation with peak, trough, breakdown, final and setback viscosities (r = −0.836, −0.846, −0.778, −0.871, and −0.847, respectively, p < 0.01). Pearson correlation was also established between the grain and starch properties. Rupture force of corn grains was positively correlated with the amylose content of starch (r = 0.950, p < 0.01).     

Non-destructive prediction of hardening pericarp disorder in intact mangosteen by near infrared transmittance spectroscopy

A non-destructive technique to predict a hardening pericarp disorder in intact mangosteen is proposed by using near infrared (NIR) transmittance spectroscopy in the wavelength range of 660-960 nm. The study found that the spectral features of normal pericarp mangosteen and hardening pericarp mangosteen were different. The averaged spectra and individual spectra of hardening pericarp mangosteen from a calibration set (N = 560) were used to develop classification models, using partial least squares discriminant analysis (PLS-DA). A model based on individual spectra obtained better classification. The overall accuracy of classification for a prediction set (N = 358) was 91%. Out of 179 samples of normal pericarp fruits, 167 were identified correctly, while 159 samples out of 179 samples with hard pericarp were predicted correctly. The results showed that NIR transmittance spectroscopy can be used to predict hard pericarp disorder in intact mangosteen fruit accurately.     

Thermal expansion coefficient and specific heat capacity from sound velocity measurements in tomato paste from 0.1 up to 350 MPa and as a function of temperature

The thermodynamic properties of food as a function of pressure and temperature are essential for modeling high-pressure processes. Sound velocity measurements in liquids at high pressure conditions are particularly interesting because they allow for deriving other properties such as the specific heat capacity or thermal expansion coefficient which are difficult to measure. By other means, in this work, the sound velocity was measured in tomato paste at high pressures with a purposed designed acoustic cell. The measurements were made in a wide range of pressures and temperatures from 0.1 to 350 MPa and from 0 to 50 °C, respectively. The sound velocity was directly measured with an accuracy of 0.1% using the transmission technique with piezoelectrics operating at 2 MHz. Thereafter, the isentropic compressibility coefficient of tomato paste was calculated from experimental data. Specific heat capacity and thermal expansion coefficient were also obtained through a software algorithm.     

Meat quality and carcass traits in relation to HGD-BstXI and HGD-HaeIII PCR–RFLP polymorphism in Chinese red cattle

We investigated the effect of homogentisate 1, 2 dioxygenase (HGD) gene on meat quality and carcass traits in 287 Chinese red cattle. The PCR–SSCP method was used to identify polymorphism of the HGD gene in the exon 1 and intron 1. Two polymorphisms were detected in intron 1 and two restriction sites for endonuclease HGD-BstXI and HGD-HaeIII have also been found. The HGD-BstXI genotypes showed significant effects on cooking loss, drip loss, net meat weight, carcass weight, and eye muscle area (P < 0.05). The HGD-HaeIII genotypes significant affected cooking loss, muscle fibre diameter, shear force, drip loss, and carcass yield ratio (P < 0.05). Moreover, we found significant effects of diplotypes on cooking loss, muscle fibre diameter, shear force, drip loss, net meat weight, carcass weight, and eye muscle area (P < 0.05).     

Effect of Lactobacillus plantarum and chitosan in the reduction of browning of pericarp Rambutan (Nephelium lappaceum)

The effects of Lactobacillus plantarum alone or in combination with chitosan were evaluated on quality and color retention in rambutan fruits (Nephelium lappaceum) stored at 25 °C and 10 °C with 75 ± 2.5% of relative humidity for 10 and 15 days, respectively. The development of the microorganisms was evidenced by viability analyses and lactic acid production. The application of L. plantarum significantly improved color retention (a* and L*), and reduced weight losses. The lactobacilli, alone or in combination with chitosan, preserved fruit quality characteristics such as firmness, total soluble solids and titratable acidity. The lactobacilli application on rambutan pericarp produced acidification of pericarp and avoided the browning; thereby desiccation was prevented due to biofilm formation.     

Predicting the density and tensile strength of viscoelastic soy powder compacts

The key physical property of compact density is important for scale up and influences the mechanical properties such as tensile strength. Hence, the objective of this research was to develop semi-mechanistic models for density of Soy Flour (SF) and Soy Protein Concentrate (SPC) powder compacts as a function of viscoelastic properties and process variables. Each of the powders was compacted at a punch speed of 5 mm/min to final compaction pressures in the range of 26–230 MPa, in a 13 mm diameter cylindrical die. Pressure–time profile during compaction, compact height and force relaxation during the dwell time were also recorded. Compact density was measured under maximum pressure and 24 h post ejection. The force relaxation data was fit to linear Maxwell model for a viscoelastic solid (R² > 0.99) and the viscoelastic properties of the pure solid material were estimated by extrapolating to zero compact porosity. Although density of compacts from either powder was found to be comparable, SPC produced much stronger compacts compared to SF due to higher bonding. The estimated compact density under pressure was found to be much higher than the pycnometer measured true densities. The contact area between two particles was estimated using Lum and Duncan-Hewitt (1999) using median particle size, pressure–time during compaction and material viscoelastic properties. Power law and logarithmic models that express the compact density and tensile strength respectively as a function of total viscoelastic contact area in a compact were successfully developed (R² > 0.95–0.99). Thus, viscoelastic properties were found to influence compact density and tensile strength through their influence on the contact area.     

Physicochemical properties and gel-forming ability of surimi from three species of mackerel caught in Southern Thailand

Physicochemical and gelation properties of surimi prepared from three species of mackerel were investigated. The highest whiteness with the lowest redness index corresponding to the lowest myoglobin content especially its oxidised form, metmyoglobin, was found in short-bodied mackerel (Rastrelliger brachysoma) surimi (p < 0.05). Frigate mackerel (Auxis thazard) surimi contained the highest lipid content (p < 0.05). The pH of all surimi was in the range of 6.58–6.80. The highest sulfhydryl group and Ca²⁺-ATPase activity was found in natural actomyosin extracted from short-bodied mackerel surimi (p < 0.05). The highest TCA-soluble peptide content was found in frigate mackerel surimi gels (p < 0.05). Kamaboko gel of short-bodied mackerel surimi exhibited the highest breaking force with the lowest expressible drip (p < 0.05). Heating regime had no effect on deformability of gels from Indian mackerel (Rastrelliger kanagurta) and short-bodied mackerel but not for frigate mackerel. The highest metmyoglobin content with the lowest whiteness was found in frigate mackerel surimi gel (p < 0.05). Therefore, short-bodied mackerel was the best suited for the production of surimi with superior functional attributes including whiteness and gel-forming ability.     

Correlation of physicochemical and nutritional properties of dry matter and starch in potatoes grown in different locations

The physicochemical and nutritional properties of dry matter and starches were studied from 13 potato varieties grown in different locations in Canada. Pearson correlation and principal component analysis were employed to examine relationships amongst variables. Phosphorus content in starch was negatively correlated to rapidly and slowly digestible starch content, while positively correlated to resistant starch content (RS) in raw dry matter and raw starch (p < 0.001). RS content of cooked starch was positively correlated to phosphorus content (0.48, p < 0.01), enthalpy of retrograded starch (0.48, p < 0.01), peak viscosity (0.52, p < 0.001) and breakdown of starch (0.43, p < 0.01). The principal component analysis grouped the 13 potato varieties by growing location, where phosphorus content in starch was the major difference. The results would imply that phosphorus content of starch was a key factor affecting physicochemical and nutritional properties of dry matter and starch in potatoes.     

Microstructure of highly concentrated tomato suspensions on homogenisation and subsequent shearing

The changes in the microstructure of tomato paste suspensions have been investigated during homogenisation and subsequent shearing in suspensions with similar composition, at three tomato paste concentrations 10, 30 and 40%. The suspensions were characterised by the particle size distribution (PSD), volume fraction (ø), and dynamic rheological properties (G′, G″). All suspensions exhibit a solid-like behaviour with G′ > G″. Micrographs indicate that the process of homogenisation creates a smooth network of finer particles, that is easily disrupted by prolonged shearing, giving rise to the formation of densely packed flocs that become clearly oriented in the direction of the shearing. At high concentrations, these changes in the microstructure on homogenisation and subsequent shearing were better reflected by differences in ø than in G′. The rheological behaviour of the suspensions exhibits a power-law dependence on ø, over a large range of PSD and for 0.05 < ø < 0.55. Finally, an experimental equation, including ø and the size of the coarse particles in the surface-weighted PSD, is found to accurately estimate G′ (R² > 99.3%, p < 0.001).     

Is there any difference between the phenolic content of organic and conventional tomato juices?

The present study aims to compare the phenolic and hydrophilic antioxidant profiles of organically and conventionally produced tomato juices. Comparisons of analyses of archived samples from conventional and organic production systems demonstrated statistically higher levels (P < 0.05) of phenolic compounds in organic tomato juices. This increase corresponds not only with increasing amounts of soil organic matter accumulating in organic plots but also with reduced manure application rates once soils in the organic systems had reached equilibrium levels of organic matter. Using principal component analysis, results show that phenolic compounds and hydrophilic antioxidant capacity were responsible for the differentiation between organic and conventional tomato juices. Thus, there appear to be genuine differences in the bioactive components of organic and conventional tomato juices not previously reported.     

Nondestructive estimation of maturity and textural properties on tomato ‘Momotaro’ by near infrared spectroscopy

Near infrared spectroscopy offers the possibility to classify and predict the internal quality of fruits and vegetables. The objective of this study was to evaluate the ability of near infrared spectroscopy to classify the maturity level and to predict textural properties of tomatoes variety “Momotaro”. Principal component analysis (PCA) and Soft independent modeling of class analogy (SIMCA) were used to distinguish among different maturities (mature green, pink and red). Partial least squares (PLS) regression was used to estimate textural properties, alcohol insoluble solids and soluble solids content of the tomatoes. The PCA calibration model with mean normalization pretreatment spectra of mature green tomatoes, gave the highest distinguishability (96.85%). It could classify 100.00% of red and pink tomatoes. The SIMCA model could not give better accuracy in maturity classification than individual PCA models. Among the textural parameters measured, the bioyield force from the puncture test with the near infrared (NIR) spectra (between 1100 and 1800 nm) pretreated by multiplicative scatter correction (MSC) had the highest correlation coefficient between NIR predicted and reference values (r = 0.95) and lowest standard error of prediction (SEP = 0.35 N) and bias of 0.19 N. The ratio of standard deviation of reference data of prediction set to standard error of prediction (RPD) was 2.71. In the case of Momotaro tomato, NIR spectroscopy by using PLS regression could not predict alcohol insoluble solids in fresh weight accurately but could predict soluble solids content well with r of 0.80, SEP of 0.210 %Brix and bias of 0.022 %Brix.     

Postharvest structural changes of Hayward kiwifruit by means of magnetic resonance imaging spectroscopy

In the present study magnetic resonance imaging (MRI) was used to evaluate the effect of storage conditions, 0 °C and 90% relative humidity (RH) or 20 °C and 70% RH, on minimal structural changes of kiwi tissue. Storage time was 35 days at 20 °C and 65 days at 0 °C including shelf life. Ethylene and respiration were followed during the experiment as well as commercial quality parameters such as sugars and firmness. MRI images weighted for proton density (ρ) and transverse relaxation times (T₂), were recorded after 10, 20, 35, 55 and 65 days. A decrease of the diameter was clearly visible in samples stored at 20 °C after 3 weeks and a coarse contour of the pericarp appeared after 40 days. Accumulation of water in the pericarp was found, suggesting a migration towards the outer regions occurs and that the fruit water loss due to evapo-transpiration is slower than the migration process. Samples stored at 0 °C showed no relevant changes in dimension and structural features for the whole period considered except after removal to shelf life. The observed variations of the internal morphology were correlated with the transverse relaxation times of defined areas and with softening of fruits. Measured T₂ profiles showed double-exponential decays, a fast- and a slow-relaxing component, indicating the existence of two different types of water molecules within cellular tissues: strongly and weakly bound, respectively. The relation among MRI data, ethylene and softening is discussed.     

Mechanical properties of tomato exocarp,mesocarp and locular gel tissues

In order to accurately predict the internal stress distribution and damage region of tomato fruit subjected to an external force using finite element method, the tomato fruit can be regarded as a multibody system which consists of exocarp, mesocarp and locular gel tissues. In the paper, these tissues’ mechanical properties of two tomato varieties were determined using different types of test. Results showed the tension failure stress and elastic modulus of exocarp tissue varied from 0.421 to 0.582 MPa and 4.601 to 9.59 MPa respectively; the compression failure stress and elastic modulus of mesocarp tissue varied from 0.122 to 0.229 MPa and 0.726 to 0.846 MPa respectively; the compression failure stress and elastic modulus of locular gel tissue varied from 0.012 to 0.016 MPa and 0.048 to 0.124 MPa respectively; the failure stress and elastic modulus values of outer layer tissue of tomato fruit were higher than those of inner layer tissue.     

Comparative study of physical and sensory properties of pre-treated potato slices during vacuum and atmospheric frying

The objective of this research was to study the effect of different processing conditions on physical and sensory properties of potato chips. Potato slices of Desirée and Panda varieties (diameter: 30 mm; thickness: 3 mm) were pre-treated in the following ways: (i) control or unblanched slices without pre-drying; (ii) blanched slices in hot water at 85 °C for 3.5 min and air-dried at 60 °C until a final moisture content of ∼0.6 kg water/kg dry solid; (iii) control slices soaked in a 3.5 kg/m³ sodium metabisulphite solution at 20 °C for 3 min and pH adjusted to 3. Pre-treated slices were fried at 120 and 140 °C under vacuum conditions (5.37 kPa, absolute pressure) and under atmospheric pressure until they reached a final moisture content of ∼1.8 kg water/100 kg (wet basis). An experimental design (3 × 2³) was used to analyze the effect of pre-treatment, potato variety, type of frying and frying temperature over the following responses: oil content, instrumental color and texture and sensory evaluation. Vacuum frying increased significantly (p < 0.05) oil content and decreased instrumental color and textural parameters. Sensory attributes, flavor quality and overall quality, were significantly improved using vacuum frying. The higher frying temperature (140 °C) increased ΔE, maximum breaking force, hardness and crispness and decreased L^* and b^* values. On the other hand, Panda potato variety improved the color of the product. A great improvement on color parameters was obtained using sulphited potato slices instead of the other pre-treatments. Although, the better flavor was obtained for control potato chips, no significant differences were found for overall quality between control and sulphited potato chips. Significant correlations (p < 0.01) between sensory and instrumental responses were found.     

Compressibility and density of select liquid and solid foods under pressures up to 700 MPa

Compressibility and density were measured at 25 °C and pressures up to 700 MPa with a variable volume piezometer for sucrose solutions (2.5–50%), soy protein solutions (2.5–10%), soybean oil, chicken fat, clarified butter, chicken breast, ham, cheddar cheese, carrot, guacamole, apple juice, and honey. Compressibility of sucrose and soy protein solutions decreased as a function of concentration (p < 0.01). For equal mass concentrations, protein solutions were less compressible (p < 0.04) than sucrose solutions at pressures greater than 200 MPa. Relative to water, fats showed high compressibility to 100 MPa, similar compressibility from 100 to 300 MPa, and less compressibility from 300 to 700 MPa. Chicken breast, ham, cheddar cheese, carrot and guacamole showed relatively large compressibility from 0.1 to 100 MPa. Honey showed the smallest volume decrease over 700 MPa. Density of all samples increased with pressure, at a decreasing rate.     

ATP-regulation of antioxidant properties and phenolics in litchi fruit during browning and pathogen infection process

The impact of energy level on antioxidant properties in relation to pericarp browning and loss of disease resistance of litchi fruit was investigated. Litchi fruits were vacuum-infiltrated with distiled water (control), 1 mM adenosine triphosphate (ATP) and 0.5 mM 2,4-dinitrophenol (DNP) under 75 kPa for 3 min before being inoculated with Peronophythora litchi or not. ATP-treated fruits presented higher activities of antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX). Higher activities of 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging, reducing power and contents of phenolic compounds were also observed in ATP-treated fruit during storage. In contrast, DNP treatment lowered the enzymes activities, scavenging ability and the contents of phenolic compounds. Higher levels of antioxidant enzymatic system and non-enzymatic system were observed in P. litchii-inoculated fruits than those in non-inoculated fruits. Application of ATP and DNP exhibited a similar change patterns and effects in inoculated fruits. When related to previously reported ATP levels, the results suggested that ATP levels could regulate the antioxidant system. Sufficient available energy is crucial for inhibiting browning and preventing the loss of disease resistance in harvested litchi fruit.