286 research outputs found
Investigation on the cause of tomato fruit discoloration and damage under chilling condition using external antioxidants and hot water treatment
No full textThe color of tomato fruit turns to red from green during ripening. The accumulated lycopene content of red tomato fruits is reduced when the fruits stored in the refrigerator. Therefore, this study was conducted in order to investigate the reason why red color tomato turns to light red when the fruit is stored at chilling temperature. A tomato variety (cv Rotarno) grown under greenhouse condition and harvested at red stage was used to assess color and firmness. Before storage at these temperatures, red tomato fruits were infiltrated by different concentration of antioxidants (Vitamin C, L-galactonic acid-¿-lactone and Butylated hydroxyanisole (BHA) and also treated by hot water. The color and firmness of the fruits were measured by pigment analyzer and Zwick, respectively. Dessicator with vacuum pump was used for infiltration of antioxidants and water. Antioxidants were infiltrated through the scar of the fruits by applying 400 Mbar pressure for 15 sec. for each concentration. Red tomatoes were treated in hot water at 40, 45 and 50°C for 2, 5 and 10 min each. All antioxidant infiltrated and hot water treated fruits were stored at 4°C for three weeks. Statistically significant difference was not observed on color and firmness among different fruits treated by different concentration of antioxidants. Hot water treatment also showed no significant difference on color value between treated and non-treated fruits. However, hot water treated fruits scored significantly higher firmness than non-treated fruits. In general, the results showed that antioxidants as well as hot water treatment did not maintain accumulated lycopene content of the red tomato fruits which, stored at chilling temperature
Low temperature-induced lycopene degradaton in red ripe tomato evaluated by remittance spectroscopy
No full textTomatoes are mostly harvested at the orange and red-ripe stages. A survey among consumers indicated that tomatoes are most often stored in the refrigerator well below 10 °C, a temperature considered harmful for chilling sensitive products such as tomato. Also during distribution, tomatoes may be exposed to chilling temperatures. The effects of storage at chilling temperatures on quality aspects of tomatoes were investigated. The colour and lycopene content of red ripe tomatoes of two cultivars (cocktail and round type) was evaluated during 20 days of storage at 4, 8, 12 and 16 °C. Colour was repeatedly measured over time by tristimulus colour measurements, RGB image analysis and colour intensity was scored by eye using a consumer panel. Lycopene content was repeatedly assessed by following the NAI index over time. This index, obtained from remittance VIS spectroscopy, was found to relate closely to the lycopene level as measured by HPLC measurements of pericarp tissue. Temperatures below 12 °C resulted in lycopene loss in ripe-red tomatoes and substantial colour loss well assessed by visual evaluation. Colour measurement using tristimulus colour measurements and RGB image analysis did not correlate well with lycopene content. Prior hot water treatment did not prevent lycopene loss. Results show that storage of red ripe tomatoes at chilling temperatures reduces the nutritional and presumed health promoting value and affects fruit visual quality
Effect of Ethylene and 1-Methylcyclopropene (1-MCP) on color and Firmness of Red and Breaker Stage Tomato Stored at Different Temperatures
No full textThe red color of the tomato fruit during ripening is due to the presence lycopene, a compound known for its antioxidant property. This compound is influenced by temperature, ethylene and 1-Methylcyclopropene (1-MCP) treatment. It was believed that ethylene application at chilling temperature could help increase the amount of lycopene content of tomato fruits. In addition, application of 1-MCP was assumed to reduce the action of ethylene on production of lycopene content and decrease loss of firmness of tomato fruit under chilling temperature. Therefore, the objective of this experiment was to see the effect of ethylene and 1-MCP treatment on color and firmness of tomato fruit under different storage temperatures. A tomato variety (cv. Rotarno) grown under greenhouse condition harvested at red and breaker stage was stored at 4, 8 and 20°C to assess color and firmness. Tomato fruits were treated by ethylene (85.7 ppm) and 1-MCP (2.9 ppm) gases starting from the first day of storage throughout the experimentation period. The color and firmness of the fruits were measured by pigment analyzer and Zwick respectively. Results showed that there was significant difference in color value of ethylene treated breaker stage tomato. 1-MCP treatment reduced the color value of tomato fruits stored at 20°C more than the fruits stored at 4 and 8°C. However, 1-MCP treatment helped to reduce loss of firmness of the fruits. We conclude that external ethylene application on red tomato fruits stored at chilling temperature generally has no effect on the subsequent accumulation of lycopene or to maintain the loss of accumulated lycopene during chilling storage. However, external ethylene treatment on breaker stage tomatoes helps for red color development. In addition, 1-MCP treatment helps to reduce loss of firmness of the fruits
Caspase inhibitors affect the kinetics and dimensions of tracheary elements in xylogenic Zinnia (<it>Zinnia elegans</it>) cell cultures
No full textAbstract Background The xylem vascular system is composed of fused dead, hollow cells called tracheary elements (TEs) that originate through trans-differentiation of root and shoot cambium cells. TEs undergo autolysis as they differentiate and mature. The final stage of the formation of TEs in plants is the death of the involved cells, a process showing some similarities to programmed cell death (PCD) in animal systems. Plant proteases with functional similarity to proteases involved in mammalian apoptotic cell death (caspases) are suggested as an integral part of the core mechanism of most PCD responses in plants, but participation of plant caspase-like proteases in TE PCD has not yet been documented. Results Confocal microscopic images revealed the consecutive stages of TE formation in Zinnia cells during trans-differentiation. Application of the caspase inhibitors Z-Asp-CH2-DCB, Ac-YVAD-CMK and Ac-DEVD-CHO affected the kinetics of formation and the dimensions of the TEs resulting in a significant delay of TE formation, production of larger TEs and in elimination of the 'two-wave' pattern of TE production. DNA breakdown and appearance of TUNEL-positive nuclei was observed in xylogenic cultures and this was suppressed in the presence of caspase inhibitors. Conclusions To the best of our knowledge this is the first report showing that caspase inhibitors can modulate the process of trans-differentiation in Zinnia xylogenic cell cultures. As caspase inhibitors are closely associated with cell death inhibition in a variety of plant systems, this suggests that the altered TE formation results from suppression of PCD. The findings presented here are a first step towards the use of appropriate PCD signalling modulators or related molecular genetic strategies to improve the hydraulic properties of xylem vessels in favour of the quality and shelf life of plants or plant parts.</p
Effect of home-refrigerator storage temperature on tomato quality
No full textPostharvest storage, handling and distribution of fruit at low temperatures is the most common and manageable approach to control ripening and subsequent deterioration and to maximize product shelf-life. However, tomatoes, as many other subtropical fruits, are susceptible to develop symptoms of chilling injury, a physiological disorder caused by the exposure to low temperature above the freezing point. Development of chilling injury depends on temperature, time, ripening stage and tomato type/cultivar. We studied the effect of home-refrigerator storage temperature on the quality of two types of tomato: cocktail tomato (cultivars ‘Amoroso’ and ‘Brioso’) and truss tomato (cultivars ‘Capricia’ and ‘Roterno’). Fully ripe tomatoes were stored for 10 days at two temperatures: 4°C as simulation of home-refrigerator storage and 15°C as an optimal storage temperature. We evaluated several quality parameters: weight loss, firmness, soluble solid content, titratable acidity, carbohydrates, titratable acidity and citrate content. Although we did not observe any apparent symptom of chilling injury, we found that 4°C temperature stimulates firmness decay in both cocktail tomato cultivars, increasing fruit susceptibility to mechanical injury. Moreover, already after 5 days of 4°C storage, tomatoes generally showed decreased sugar and increased acid content (especially in cocktail tomatoes) compared to 15°C stored fruit, indicating a loss of sensoric quality at 4°C
Quantifying lycopene synthesis and chlorophyll breakdown in tomato fruit using remittance VIS spectroscopy
No full textThe aim of this study was to increase the understanding of chlorophyll breakdown and lycopene synthesis at a quantitative level in Solanum lycopersicum fruit. To accomplish this, a kinetic model is proposed describing the transition from chloro- to chromoplast. Remittance VIS spectroscopy was used to assess chlorophyll and lycopene levels non-destructively in cocktail and round type tomatoes. Tomatoes were stored at constant temperatures between 4 and 24 °C, or at a stepwise changing temperature between 4 and 16 °C. Chlorophyll and lycopene levels were measured repeatedly over time and used to calibrate a kinetic model that describes how an autocatalytic enzyme system links chlorophyll breakdown to lycopene synthesis, including breakdown of lycopene precursor and lycopene itself. Increasing storage temperatures increased the reaction constant for lycopene synthesis more than that of chlorophyll breakdown for both tomato types. The reaction constants describing chlorophyll breakdown and lycopene synthesis were considerably larger, and the estimated enzyme levels lower for the round type. This allows round tomatoes to quickly resume lycopene synthesis after a cold storage period when enzyme levels are low. Lycopene breakdown was established for the round type while the cocktail type showed lycopene precursor breakdown. Chlorophyll breakdown and lycopene synthesis, as affected by storage temperature and tomato type, is covered well by the model for both tomato types. We hypothesise that the postulated enzyme system, responsible for the direct link between chlorophyll breakdown and lycopene synthesis, is due to STAY-GREEN proteins. Remittance VIS spectroscopy is, in combination with a parameter estimation tool, suited to screen tomato genotypes for intended colour transformation performance, or as tool in chloroplast to chromoplast transition studies
Greenhouse climate control affects postharvest tomato quality
No full textIn this study, important quality properties such as firmness, sugar and acid levels were measured and analysed in tomatoes harvested from three greenhouses during a five month period and stored at 16 degrees C for over 20 days. Tomatoes were harvested from three identical, neighbouring, greenhouses which were either conventionally ventilated (open greenhouse) or mechanically cooled (semi-closed greenhouses). Sugar and acids levels were hardly affected by greenhouse type. Compared to the open greenhouse, semi-closed greenhouses produced heavier and less mature (firmer) fruit at the commercial harvesting stage based on colour. Fruit maturity differences could be linked to the vertical temperature gradient and to CO2 levels in the different greenhouses. This indicates that CO2 levels and temperature affect the synchronisation between colour and firmness maturity at harvest. The acceptance period, i.e., the time period both tomato colour and firmness are considered acceptable by consumers, will likely be positively affected when growers switch from conventionally ventilated to semi-closed production systems. Additional to greenhouse effects also effects of the harvest month were observed. The sugar to acid ratio was highest and glucose to fructose ratio was lowest in July, the month with the highest irradiance, irrespective of greenhouse type. The estimated value for the maximum firmness (F-max) varied from 17.9 N in August to 31.2 N in June. This monthly variation in F-max explains an important part of the variation found in the postharvest behaviour of tomatoes. Interestingly, the monthly variation in F-max showed the same trend as found for the monthly initial sugar levels. It might be hypothesised that the monthly variation in glucose and fructose levels causes variation in that part of firmness that is generated by cell turgor. The monthly variation in F-max, sugar and acid levels could not be linked to climate conditions and remains to be elucidated. (C) 2013 Elsevier B.V. All rights reserved
Non-destructive detection of flawed hazelnut kernels and lipid oxidation assessment using NIR spectroscopy
No full textMicrobial contamination, seed browning, bad taste and lipid oxidation are primary causes of quality deterioration in stored hazelnuts, affecting their marketability. The feasibility of NIR spectroscopy to detect flawed kernels and estimate lipid oxidation in in-shell and shelled hazelnuts was investigated. ‘Mortarella’ hazelnuts were measured twice by NIR spectroscopy, first in-shell, and then as kernels. Afterwards, the kernels were evaluated visually, externally and internally, and by sensory evaluation with a subsequent measurement of fat oxidation. A satisfactory PLS model was created for the detection of flawed kernels. For lipid oxidation estimation the best performance of PLS models was obtained by first removing the flawed kernels from the calibration set. The PLS model for the K232 extinction coefficient, that is indicative of lipid primary oxidation, was able to predict K232 for both in-shell (R2 = 0.79) and shelled (R2 = 0.85) hazelnuts. Our results suggest, for shelled hazelnuts, a two-step NIR procedure: a first PLS model to detect and separate flawed kernels and then a second PLS model to grade healthy kernels by lipid oxidation levels
Advances in plant ethylene research
No full textThe rapid advances in elucidating the biosynthesis and mode of action of the plant hormone ethylene as well as its involvement in the regulation of the whole plant physiology made imperative the organization of a series of dedicated conferences. This volume contains the main lectures and poster contributions presented at the 7th International Symposium on the Plant Hormone Ethylene held in Pisa in 2006. The book is organized in seven sections dedicated to 1) Ethylene biosynthesis, perception and signal transduction, 2) Interactions between ethylene and other hormones, 3) Role of ethylene in plant growth and differentiation, 4) Fruit development, ripening and quality, 5) Abscission and senescence, 6) Ethylene involvement in biotic and abiotic stresses, and 7) Biotechnology and applied aspects. The most reputed scientists active in the specific topics contributed with original papers and as editors of the related chapters.
This book is expected to be of great interest to scientists, researchers, undergraduate and graduate students, interested in the progress made in plant ethylene research and biotechnology
- …
