Enzymatic Firming of Processed Red Pepper by Means of Exogenous Pectinesterase

The objective of this investigation was to demonstrate that the firmness of a commercial vegetable product, diced and frozen red pepper (Capsicum annum var. Sendt), could be improved by the use of exogenous pectinesterase in an industrially relevant process. The diced pepper pieces 10 × 10 × 7 mm³ were infused under vacuum with a commercially available pectinesterase. The range of optimal process conditions was: 15-20°C, 45 min infusion time, a 10-25 mM CaCl₂ infusion brine, a w/w ratio of pepper fruit to infusion brine of 1.5:1, and an enzyme dosage of 30-60 pectinesterase units (PEU) per kg pepper fruit. The firmness as measured by back extrusion was improved by a factor of two to three. The effect of firming was robust and conserved after freezing and heating in a simulated household cooking process. The firming process seems easily adaptable to industrial conditions and may be applicable to other vegetable and fruit products.     

Monitoring of Zn(II), Cd(II), Pb(II) and Cu(II) During Refining of Some Vegetable Oils Using Differential Pulse Anodic Stripping Voltammetry

In this study, a novel approach has been developed using differential pulse anodic stripping voltammetry (DPASV) for the simultaneous determination of Zn(II), Cd(II), Pb(II) and Cu(II) in edible oils at hanging mercury drop electrode. The microwave digestion of oil samples was carried out with concentrated HNO₃ and H₂O₂. KNO₃ was used as a supporting electrolyte. The experimental conditions optimized such as deposition time, stirring rate and size of mercury drop were 300 s, 600 rpm and 10 mm², respectively. The method was applied to quantify Zn(II), Cd(II), Pb(II) and Cu(II) in crude and refined hazelnut, corn, sunflower and olive oils. During refining of different vegetable oils, the removal efficiencies of Zn(II), Cd(II), Pb(II) and Cu(II) were calculated as 98.20–99.91, 98.50–99.90, 95.26–99.76 and 95.93–99.92 %, respectively. The limits of detection for Zn(II), Cd(II), Pb(II) and Cu(II) were 2.1?×?10^?8, 8.7?×?10^?10, 7.1?×?10^?9 and 3.4?×?10^?9 and the limits of quantification were 6.8?×?10^?8, 2.9?×?10^?9, 2.3?×?10^?8 and 1.1?×?10^?8 M with linear regression coefficients (R ²) of 0.9930, 0.9928, 0.9893 and 0.9931, respectively. It was observed that the above metals in crude and refined vegetable oils could be determined simultaneously by the DPASV method.     

Firmness and Cell Wall Characteristics of Pasteurized Jalapeño Pepper Rings as Affected by Preheating and Storage

Changes in cell wall pectic substances, degree of pectin methylation, bound calcium and firmness were determined in preheated and nonpreheated fresh pack jalapeño pepper rings stored for 5 mo. Pepper rings preheated for 60 min at 50°C in a brine solution (8% NaCl and 0.2% CaCl₂, were firmer, had more nonextrctable pectins (NXP), more bound calcium, less water-soluble and chelator-soluble pectins (CSP), and less pectin methylation than nonpreheated pepper rings. The greater formation and maintenance of nonextractable pectins, which resisted acid hydrolysis during pasteurization and storage is probably an important factor in firming.     

Modeling of Salt Diffusion in White Cheese during Long-Term Brining

Salt transport in white cheese was investigated at two brine concentrations (15 and 20% w/w) and at three temperatures (4, 12.5 and 20°C) for each brine concentration. Two mathematical models were developed based on treating the cheese samples as finite or semi-infinite bodies. Theoretical and experimental salt concentration profiles were in good agreement. The semi-infinite model was valid only for low Fourier numbers, i.e., Fo≤0.07. Effect of convectional flow was insignificant. Salf diffusivity remained constant with time, and an Arrhenius-type equation described its variation with temperature. Salt diffusivity in white cheese was estimated as 0.21 × 10^?9 m²/sec at 4°C and 0.31 × 10^?9 m²/sec at 12.5°C for both brine concentrations and as 0.39 × 10^?9 m²/sec for brine concentration 15% (w/w) and 0.34 × 10^?9 m²/sec at 20°C for 20% (w/w).     

Osmotic Dehydration of Nectarines: Influence of the Operating Conditions and Determination of the Effective Diffusion Coefficients

The aim of the present work is to study the kinetics of osmotic dehydration of Caldesi nectarines (Prunus persica var. nectarina) evaluating the effect of osmotic solution concentration, type of solute, temperature, fruit/solute ratio and process time on moisture content, water loss, soluble solids content and solids gain. The process analysis was carried out experimentally and numerically through the mathematical modelling of mass transfer. Hypertonic solutions of glucose syrup and sorbitol (40 and 60 % w/w) were used for dehydration, during 2 h of process at temperatures of 25 and 40 °C, with fruit/osmotic agent ratio of 1:4 and 1:10. Water loss and solids gain showed significant differences depending on the type and concentration of the osmotic agent, process time and fruit/solution ratio. The concentration interacted significantly with all variables; in addition, there was an interaction between the type of osmotic agent and the relationship between fruit and the osmotic agent. The effective diffusion coefficients were obtained from the analytical solution of Fick’s second law applied to flat-plate geometry and by solving the mass transfer microscopic balances by finite element method, taking into account the real geometry of the nectarine pieces. The values obtained from Fick’s law varied between 1.27?×?10^?10 and 1.37?×?10^?08?m²?s^?1 for water and from 1.14?×?10^?10 to 1.08?×?10^?08?m²?s^?1 for soluble solids, while the values calculated by finite elements method ranges were between 0.70?×?10^?09 and 4.80?×?10^?09?m²?s^?1 for water and between 0.26?×?10^?09 and 1.70?×?10^?09?m²?s^?1 for soluble solids. The diffusion coefficients values obtained from the numerical solution are consistent with those published in literature.     

Respiration,pectolytic activity and textural changes in ripening African mango (Irvingia gabonensis) fruits

Post-harvest changes in fruit firmness, respiration, pectinesterase (PE) and polygalacturonase (PG) activities were followed in African mango fruits during storage ripening at tropical ambient conditions (28±1°C and 68±2% RH). Respiration followed a climacteric pattern attaining a peak of 99·37 ml CO₂ kg^?1 hr^?1 on the fifth day of storage while full ripeness (colour index—5) was attained on the tenth day. PE and PG activities increased with progressive fruit ripening attaining their optima on the fifth day (1·8 PE unit) and tenth day (27 PG units), respectively. Fruit firmness decreased as pectolytic activity increased with a concomitant reduction in the deformation force from 49 kPa in the unripe fruit to 25 kPa at the edible ripe stage.     

Influence of 1-Methylcyclopropene (1-MCP) on Postharvest Storage Quality in Green Bell Pepper Fruit

The goal of this research was to evaluate the efficiency of 1-methylcyclopropene (1-MCP) on maintaining the quality parameters and antioxidant activity of bell pepper cv. Selika (an original red cultivar) and cv. H1530 (??ever-green?? line) after 18?days storage at 7°C and 3?days at 20°C. Fruits were harvested at green color, from a commercial shade net house in the desert region in Israel. In both cultivars, 600?nL?L^?1 1-MCP reduced weight loss and maintained firmness more than control or 900?nL?L^?1 1-MCP. Overall, 1-MCP treatment had a pronounced effect on delaying ripening processes as shown by inhibiting color changes, decreasing decay, and maintaining quality of non-climacteric green pepper fruit. 1-MCP treatment reduced the lipophilic antioxidant activity of this fruit, but the hydrophilic antioxidant activity remained similar to that observed at harvest.     

Pasting,thermal, gel texture,resistant starch and colour properties of unripe banana flour from 10 desert banana varieties cultivated in South Africa

Unripe banana flour is a potential commercial ingredient in various food products for increased resistant starch and reduced gluten contents. In the present study, the pasting (rapid visco-analysis), gel texture (penetration test), thermal (differential scanning calorimetry), colour (tri-stimulus colour indices) and the resistant starch properties of unripe banana flour produced from different dessert banana varieties (n?=?10) cultivated in South Africa, were analysed and juxtaposed to wheat and maize flour. The functional properties varied significantly (p?≤?0.05) between banana varieties, and from wheat and maize flours, to various extents. Selected functional property ranges of unripe banana, wheat and maize flours, respectively included; flour colour index (63.16–76.42, 77.34 and 80.96), paste viscosity (405.5–556.6, 124.7 and 115.6 RVU), gelatinization temperature (64.67–71.21, 71.11 and 69.95?°C), gel firmness (7.24–11.44?×?10^??2 N, 3.49?×?10^??2 N and 6.56?×?10^??2 N) and resistant starch content (19.9–47.4, 2.8 and 2.2% w/w). Multivariate analysis (principle component analysis) showed that the unripe banana flours from different varieties were distinguished from each other based on the pasting temperature. The unripe banana flours were distinguished from both wheat and maize flour based on breakdown and peak paste viscosities. The breakdown viscosity was the most positively related measure to the resistant starch content with a linear regression R-squared value of 0.898, indicating a significant role played by granule structure in resistance to enzymatic hydrolysis. The present research demonstrates that selection of appropriate dessert banana variety is important when replacing staple flours (wheat and maize) with unripe dessert banana flour as a functional ingredient.     

Effect of Blanch Temperature on Kinetics of Thermal Softening of Carrots and Green Beans

Cut green beans and diced carrots were blanched at 100°C and 74°C then canned and processed for 5 min to 300 min at 100°C. In every case the rate of thermal softening was consistent with the two substrate first-order kinetic theory of thermal softening of vegetable tissue. The low temperature blanch caused some changes in the apparent firstorder rate constants for both substrates, but the major difference was a much higher intercept of the extrapolated substrate S_S line on the firmness axis. We define S_S at zero process time as the “thermal firmness value” because it is a good indicator of what the firmness of the vegetable will be after canning.     

REDUCTION IN MICROBIAL GROWTH AND IMPROVEMENT OF STORAGE QUALITY IN FRESH-CUT PINEAPPLE AFTER METHYL JASMONATE TREATMENT

Maintaining the quality of a fresh‐cut fruit or vegetable product is a major concern and a priority in the development and in the production of fresh‐cut produce products of the industry. The industry has been searching for alternative methods to protect fresh‐cut produce from decay and to prolong shelf life. The objective of this research is to enhance the quality and the shelf life of fresh‐cut pineapple by exposure to methyl jasmonate (MJ). The exposure of the diced pineapple to a MJ emulsion at a concentration of 10 ^?4 M for 5 min in a sealed container decreased microbiological growth by 3 logs after 12 days of storage at 7C, compared with the control pineapple. Methyl jasmonate as vapor or as dip did not affect the firmness or the color of the fruit. Methyl jasmonate may be a practical treatment to ensure the safety and the quality of fresh‐cut pineapple and other fruits and vegetables.     

Vacuum Infiltration of Polyamines Increases Firmness of Strawberry Slices Under Various Storage Conditions

Strawberry slices were vacuum infiltrated with polyamines and changes in firmness during storage were determined. Spermine and spermidine at 10 mM or 100 mM significantly increased firmness, whereas pu-trescine was not as effective at increasing firmness of slices stored at 1°C. The firming effect of the polyamines was similar to that of calcium chloride, and may have been due to their ability to bind to cell walls and membranes. In ripe receptacles of various cultivars which differed in firmness, putrescine (12–38 nmol/g fresh weight) and spermidine (19–33 nmoI/g fresh weight) were the predominant polyamines, while only low levels of spermine (<10 nmol/g fresh weight) were present. There was no discernible relationship between endogenous polyamine levels and fresh fruit firmness for the cultivars studied.     

Mechanical flower thinning improves the fruit quality of apples

BACKGROUND: Apple ‘Golden Delicious Reinders’ and ‘Gala Mondial’ trees were mechanically blossom‐thinned with 30–77 × g (300–480 rpm rotation) and 5 or 7.5 km h^?1 vehicle speed to improve fruit quality, minimise leaf damage, reduce hand and chemical thinning and to prevent or overcome alternate bearing; adjacent untreated or manually thinned apple trees served as controls. RESULTS: Mechanical thinning (43 × g, 360 rpm, 5–7.5 km h^?1) had a positive effect on fruit size (15% larger), firmness (8.4 in Gala vs. 7.6 kg cm^?2 in the unthinned control), sweetness (124 vs. 117 g kg^?1 sugar in the control), contained the largest malic acid content (4 g kg^?1 vs. 3.4 g kg^?1 in the control) and 17% more anthocyanin (normalised anthocyanin index = 0.8 in Gala vs. 0.7 in the control); fruit of Golden and Gala showed additionally advanced starch breakdown and ripened earlier. CONCLUSIONS: Since increases in rotor speed, viz. centrifugal force, versus increases in the vehicle speed resulted in opposing effects, an integrated coefficient of thinning (ICT) was devised with optimum values of 10–40 (at 43 × g, 5–7.5 km h^?1), where an ICT > 50 led to tree damage and ICT < 8 led to sub‐optimum thinning efficacy. Copyright © 2010 Society of Chemical Industry     

Effects of exogenous nitric oxide on contents of soluble sugars and related enzyme activities in 'Feicheng' peach fruit

BACKGROUND: Sugar content is one of the main characteristics related to the quality of fruit. Research confirms that nitric oxide (NO) involves a physiological process and prolongs the storage life of fruit. However, little attention has been paid to the effects of NO on sugar metabolism in fruit during storage. In this study, the effect of different concentrations (0, 10, 30 µmol L^?1) of exogenous NO treatment on sugar content and related enzyme activities in ‘Feicheng’ peach fruit was investigated during storage (0–12 days after harvest) at room temperature (25 °C). RESULTS: Results showed that the decrease of firmness and accumulation of sugar and acid:sugar ratio in peach fruit during storage were significantly inhibited by treatment with 10 µmol L^?1 NO. Treatment with 10 µmol L^?1 NO could promote fructose and glucose metabolism during the first 4 days of storage, and increase the content of sucrose and the activities of sorbitol dehydrogenase, sorbitol oxidase and sucrose phosphate synthase in peach fruit during storage. However, acid invertase activity from 8 to 12 days of storage and neutral invertase activity during the first 4 days of storage were inhibited by treatment with 10 µmol L^?1 NO. At the same time, treatment with 10 µmol L^?1 NO inhibited sucrose synthase (SS) activity in decomposition during storage and SS activity in synthesis from 8 to 12 days of storage. CONCLUSION: Treatment with 10 µmol L^?1 NO had a significant impact on content of soluble sugars and related enzyme activities in ‘Feicheng’ peach fruit during storage (0–12 days) at room temperature (25 °C). Copyright © 2011 Society of Chemical Industry     

EFFECTS OF RAW MATERIALS AND PROCESS VARIABLES ON THE HEAT PENETRATION TIMES, FIRMNESS, AND PECTIC ENZYME ACTIVITY OF DICED TOMATOES (HALLEY BOS 3155 CV)

The effects of raw materials and process variables on the heat penetration times into diced tomatoes (Halley Bos 3155 cv) were evaluated. Variables included dice size (1.27 and 2.54 cm), maturity at harvest (red and red+2 weeks), and processing temperature (88 and 92C). Heat penetration times between dice sizes were significantly different, but not between maturities or processing temperatures. Tomatoes were also evaluated for firmness, pectin-methylesterase (PME) and polygalacturonase (PG) activities. Half-inch size diced tomatoes were processed at 88 and 92C, and evaluated for firmness using the shear-compression method. Firmness decreased to 60% of the initial raw firmness from 8.8 × 10⁵ to 5.3 × 10⁵ g-mm after 15 s at 88C, and to 50% from 8.8 × 10⁵ to 4.4 × 10⁵ g-mm after 15 s at 92C. Diced tomato firmness showed a slight firming trend after 150 s at both temperatures. PME was inactivated after 45 s, while 5% residual PG activity remained after 3 min.     

Edible Coating Effects on Postharvest Quality of Green Bell Peppers

Green bell pepper fruits (Capsicum annuum L., cv. “Jupiter”) were coated with a mineral-oil-based coating or a cellulose-based coating. Three different milk-protein-based edible coatings (whey protein isolate, sodium caseinate, and sodium caseinate beeswax emulsion) plasticized with glycerol were also tested. The effects of these coatings were followed by measurement of changes in respiration, internal gases, color, firmness, and water loss during storage at 10°C, 80–85% RH for 20 days. None reduced respiration or affected color. Only the mineral-oil-based coating significantly reduced moisture loss, thus maintaining fruit firmness and thereby prolonging fruit freshness.     

Comparison of the modeled potential yield versus the actual yield of maize in Northeast China and the implications for national food security

A precise spatial knowledge of potential yield and actual yield is crucial to assessing an increase in grain yield and is relevant to national food security. In this paper, the potential maize yields at the county level in 2013 in Northeast China were estimated using a Miami model in combination with an integrated fertility index and the effect of chemical fertilizers on yield increase. Then, the spatial characteristics of the climate, farmland and grain production potential were presented, and the potential yield increase and food security implications were analyzed. The estimated production potentials of the climate, farmland and grain in 2013 were approximately 4.65?×?10³–13.06?×?10³ kg/ha, 2.77?×?10³–9.38?×?10³ kg/ha, and 2.97?×?10³–12.1?×?10³ kg/ha, respectively, whereas the actual maize yield in 2013 was 1.50?×?10³–8.60?×?10³ kg/ha, accounting for 41.86–95.84 % of the grain production potential. The total average potential maize increase in Northeast China was 3.32?×?10³ kg/ha, measured from the difference between the climate production potential and the actual yield. Furthermore, the main regions with lower surplus production but a higher potential for increase were located in the eastern Liaoning, Jilin and Heilongjiang Provinces. In addition, the surplus production, which was 136.56 million tons, could feed 341.4 million people in other areas of China. In conclusion, we suggest that improving access to agronomic practices (such as fertilizer and high-yielding seed) and developing agricultural policies and strategies could increase the maize yield and further narrow the yield gap.     

Effect of different solvents on volatile and non-volatile constituents of red bell pepper (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.) and their in vitro antioxidant activity

The fresh fruit of Capsicum annuum L. (red bell pepper) was successively extracted using n-hexane, chloroform, ethyl acetate, ethanol and their percentage yield was calculated. The effectiveness of each extract on chemical composition and antioxidant activity was studied. The qualitative phytochemical evaluation of each extract of bell pepper was done by HPTLC and Gas chromatography–mass spectroscopy (GC-MS) analysis. The total content of phenols, flavonoids and carotenoids were estimated by standard chemical methods. Further, the antioxidant potential of each extract was measured via DPPH and reducing power assays. Gas chromatography–mass spectroscopy analysis showed that the majority of compounds were related to phenols and flavonoids. Further analysis of the extract by HPTLC verified the presence of different types of phenolic compounds in addition to flavonoids and carotenoids. Among the different solvent extracts analyzed, total phenolic content was higher in ethanol extract (7.136?±?0.03%, w/w) whereas ethyl acetate extract showed the presence of higher flavonoid content (4.0521?±?0.03%, w/w). The ethanol and ethyl acetate extracts of the fruit of C. annuum exhibited the highest radical scavenging activity with inhibition percentage of 53.66 and 49.55% at a concentration of 254 µg/ml. Based on the biochemical analysis and phytochemical screening, we conclude that C. annuum possess potent antioxidant potential and this ability of the extract is attributed to the presence of rich polyphenolic compounds.     

Carbon Nanotube–Ionic Liquid (CNT–IL) Nanocamposite Modified Sol-Gel Derived Carbon-Ceramic Electrode for Simultaneous Determination of Sunset Yellow and Tartrazine in Food Samples

Carbon-ceramic electrode modified with multi-walled carbon nanotubes–ionic liquid (MWCNTs–IL) nanocomposite was constructed. This electrode was used for electrochemical determination of food dyes Sunset Yellow (SY) and tartrazine (Tz). The modified electrode based on high surface area and high ionic conductivity of nanocomposite exhibited electrocatalytic effect for oxidation of SY and Tz; also, oxidation peak potentials of SY and Tz effectively separated on modified electrode, and their simultaneous determination was possible. Operational parameters, such as the amount of MWCNTs in suspension, IL volume, solution pH, and scan rate, which affect the analytical performance of determination, were optimized. The present electrode behaved linearly to Sunset Yellow and tartrazine in the concentration range of 4?×?10^?7 to 1.1?×?10^?4?M and 3?×?10^?6 to 0.7?×?10^?4?M with a detection limit of 10^?7?M (0.045 mg?L^?1) and 1.1?×?10^?6?M (0.59 mg?L^?1), respectively. The proposed method was successfully utilized for simultaneous determination of SY and Tz in different food samples, and the obtained results were in good agreement to those obtained by HPLC method.     

Application of inverse methods in the osmotic dehydration of acerola

This work presents a study of the mass transfer of osmotically dehydrated West Indian cherry, also known as acerola. The experiments were performed by immersing the fruits in a sucrose solution at 65ºBrix for 12 h at ambient temperature (27 °C), using three different fruit:solution ratios (1:4; 1:10 and 1:15 (w:w)). The kinetics of water loss, solids gain and weight reduction was determined. Effective mass diffusivity was calculated by the inverse method, using the Levenberg‐Marquardt minimisation algorithm. The mathematical model used to describe the physical phenomenon of osmotic dehydration was based on Fick’s Second Law, considering the fruits as geometrically perfect spheres. The influence of the fruit:solution ratio was not significant in the range of this study. Diffusivity ranged from 1.558 × 10^?10 to 1.760 × 10^?10 m² s^?1.     

Optimization of Covalent Immobilization of Extracellular Ice Nucleators from Erwinia herbicola on Magnetic Fe3O4/Chitosan Nanoparticles for Potential Application in Freeze Concentration

A magnetically separable extracellular ice nucleators (ECINs) immobilized system was constructed, ECINs from Erwinia herbicola were covalently immobilized on magnetic Fe₃O₄/chitosan nanoparticles by coupling via glutaraldehyde (GA) or epichlorohydrin (ECH). The immobilization process parameters were optimized, and under optimized conditions, ice nucleation activity (INA) of GA and ECH immobilized ECINs reached at 1.56?×?10⁶?±?1.54?×?10⁵ Units/mg and 1.62?×?10⁶?±?1.91?×?10⁵ Units/mg, respectively. The stability, reusability and cytotoxicity of GA and ECH immobilized ECINs were characterized and compared; both GA and ECH immobilized ECINs demonstrated good reusability performance after 15 freeze–thaw cycles and low cytotoxicity, while GA immobilized ECINs were recovered more easily and more stable at different pH compared to ECH immobilized ECINs. Application of the immobilized ECINs in freeze concentration was investigated, and an increase of ice nucleation temperature for water, seawater and apple juice (6.83?±?0.18 °C, 8.08?±?0.50 °C and 9.38?±?1.12 °C) was achieved by using GA immobilized ECINs. The results collected so far show that there are extensively promising applications for GA immobilized ECINs in freeze concentration industry fields.