Proceedings of the International Conference “Environmentally friendly and safe technologies for q... more Proceedings of the International Conference “Environmentally friendly and safe technologies for quality of fruit and vegetables”, held in Universidade do Algarve, Faro, Portugal, on January 14-16, 2009. This Conference was a join activity with COST Action 924.The colour of apples (flesh colour or skin colour) was assessed using the same individual apples repeatedly in time at three different locations, in several seasons for five different cultivars. Two experiments were conducted in the orchard, one experiment during postharvest storage. The same logistic model was applied to analyse the data, separate for each location and cultivar. Non linear mixed effects regression analysis allows to extract not only information on the kinetic parameters like reaction rate constant and potential greenness, but also on the variation present in the data. The rate constant of the decolouration process was found to be largely the same for all combinations (with one exception). The variation in biological shift factor, as an expression for maturity, seems to be independent of orchard location and only slightly dependent on orchard management procedures. The main differences observed are in the potential greenness of the apples (colmin) that vary considerably between successive seasons and between cultivars. The applied technology provides the necessary tools to analyse the effects of season and orchard management, for all locations in the study. It opens wide alleys to investigate more dedicated the effects of weather, season, management and orchard location in growing apples with a constant quality (colour) over the seasons, locations and management procedures
The fruits of four different plum cultivars 'Cacanska lepotica', 'Valor', 'St... more The fruits of four different plum cultivars 'Cacanska lepotica', 'Valor', 'Stanley', and 'Tophit' were analysed for antioxidant activity, which was evaluated in plum extracts using ABTS assay. The results obtained showed that the antioxidant activity depended on the cultivar. The highest antioxidant activity was estimated in ‘Valor’ plums (18.6 μmol of Trolox equivalent (TE)/g of fresh weight (FW)), followed by cultivars 'Cacanska lepotica' (12.8 μmol TE/g FW) and 'Stanley' (11.4 μmol TE/g FW), whilst cultivar 'Tophit' showed the lowest value (10.8 μmol TE/g FW).
In this study, we focused on the possibility of forecasting the development of skin color in appl... more In this study, we focused on the possibility of forecasting the development of skin color in apples on the basis of weather forecast by using a machine learning methods. We used supervised learning and generated models via the use of six decision trees. The purpose of the research was to build models that would allow for in-practice-acceptable accuracy in the prediction of the development of fruit skin color (especial a colour parameter a*), for three apple varieties. For cv. ‘Gala, Brookfield’, the most accurate models were generated by using decision tree J48 (89.13% accuracy). For late ripening cv. ‘Fuji, Kiku 8’ and cv. ‘Braeburn, Maririred’, the most accurate model was obtained by using decision tree LMT (91.73 and 96.65% accuracy). The data confirm that the applicability of predictive models strongly depends on the accuracy of weather forecasts. In regard to the seven-day weather forecast, which was used for expert models, the accuracy of the models was, on average, reduced by 10.73%.
Abstract Size is an important property of all fruit as it determines, together with crop load, fr... more Abstract Size is an important property of all fruit as it determines, together with crop load, fruit yield. The aim of this study is to model the increase in fruit size during cell expansion based on diameter or length and to predict fruit size and volume, including the variation in size and volume, at harvest. The size of individual fruit during growth of fruit (four apple, two tomato and six pepper cultivars) was measured from early fruit set until harvest at several seasons. Size data were evaluated as diameter and length using the von Bertalanffy growth model, adapted to include the variation in size between individuals and the effect of growing temperature. The adapted von Bertalanffy model describes the increase in diameter and length and their variation. For any fruit type, size increased along the same generic growth model. A single stochastic variable, the biological shift factor, was sufficient to describe the variation in development time, initial size and maximum size. For all batches the percentage variation explained for were well over 93% with growth rate constants similar per species and only a minor effect of growing temperature. Prediction of the maximum size distribution based on measurements half way the cell expansion period is explored and discussed. Size and its distribution can be predicted based on a single measuring point in time but with two or three points in time the prediction system becomes more robust.
Biological variation is omnipresent in nature. It contains useful information that is neglected b... more Biological variation is omnipresent in nature. It contains useful information that is neglected by the usually applied statistical procedures. To extract this information special procedures have to be applied. Biological variation is seen in properties (e.g. size, colour, firmness), but the underlying issue is almost always to the variation in development or maturity in a batch of individuals generated by small scale environmental differences. The principles of assessing biological variation in batches of individuals are explained without putting emphasis on mathematical details. Obtained explained parts increase from about 60 to 80 % for the usual approach to 95 when the biological variation is taken into account. When technical variation or measuring error is small even 99 % can be achieved. The benefit of the presented technology is highlighted based on a number of already published studies covering the colour of apples during growth and storage and the firmness of cut tomatoes d...
Sažetak U voćarskom centru Maribor -Gačnik u 2010. godini smo proučavali razvoj pojedinih paramet... more Sažetak U voćarskom centru Maribor -Gačnik u 2010. godini smo proučavali razvoj pojedinih parametara zrelosti i kvalitete ploda šljive Prunus domestica L. U pokusu su bile sorte šljive Valor i Stanley. Cilj istraživanja bio je utvrditi optimalno vrijeme berbe za pojedine sorte šljive i odnose između pojedinih parametara zrelosti i kvalitete. Eksperimentalni rezultati su pokazali da boja kao parametar kvalitete i zrelosti kod različitih sorti šljiva nije dobar pokazatelj optimalnog vremena berbe, jer se u godini istraživanja boja kožice ploda kod sorte Valor razvila 17, a kod sorte Stanley 10 dana prije konzumnog dospijeća plodova utvrđenog drugim parametrima kakvoće. Ključne riječi: šljiva, zrelost, boja kožice Plum -the issue of harvest date Abstract At Fruit growing Centre Maribor -Gačnik in 2010 we investigated the development of certain parameters of maturity and quality of plum (Prunus domestica L.). In the experiment were included plum cultivar 'Valor' and 'Stanley...
Anti-hail nets for the production of apples has become a normally action for a new or update an o... more Anti-hail nets for the production of apples has become a normally action for a new or update an old apple orchard. In 2007 and 2008, the development of quality and maturity parameters of cv. 'Gala Brookfield' and ‘Fuji Kiku 8' apples grafted on M9 were studied in the Fruit growing centre Maribor-Gačnik as a factor of being grown under a blackhail net. The results showed that when grown under the black hail net fruit of both cultivars reach a higher mean mass, lower soluble solids content (0.6 to 1 ° Brix), and lower starch index, while no effect of the black hail net was detected on fruit flesh firmness and yield.
ABSTRACT The purpose of this study was to evaluate the contribution of extractable antioxidants a... more ABSTRACT The purpose of this study was to evaluate the contribution of extractable antioxidants and non-extractable phenolics to the total antioxidant activity (TAA) of plums. Therefore, the antioxidant activity was determined (ABTS assay) in aqueous–organic extracts, as well as in the extraction residues which were a subject of two different acidic treatments to release hydrolysable tannins and non-extractable proanthocyanidins (NEPA). In addition, the changes in TAA during the last week of ripening were investigated. Extractable antioxidants contributed less than 18% to the TAA, considerably higher values of antioxidant activity were associated with hydrolysable tannins and NEPA, suggesting that the antioxidant activity of plums may be underestimated in the literature. The ripening resulted in an increase of TAA up to 38% in excess of the value determined on the first sampling date. TAA showed a similar pattern over the ripening period for all cultivars studied.
Samples were taken from apple flesh while at the tree ('Gala' and 'Pinova') using... more Samples were taken from apple flesh while at the tree ('Gala' and 'Pinova') using a biopsy sampling system. After sampling the wound was closed with vaseline, which prevented wound responses. Samples were taken at different times over the circumference of the apples (at about 70 above the equator) to monitor the spatiotemporal distribution of acids (malic, citric, fumaric) and sugars (glucose, fructose and sucrose). At the same time the skin colour was assessed with a Minolta colour meter at the same location. The distribution over the circumference of the apples revealed for both cultivars a sinusoidal pattern for all colour aspects and for citric acid, while only fructose in 'Gala' showed a clear sinusoidal pattern. For all other variables measured, the pattern was only faint, with a low amplitude. Although the system is still prone to a large measuring error, biopsy sampling is a powerful tool to study the spatio-temporal distribution of taste components.
Traditionally, crop load and fruit yield from previous seasons are used as indicators for predict... more Traditionally, crop load and fruit yield from previous seasons are used as indicators for prediction of fruit size. Disregarding the inevitable biological variation between fruit, von Bertalanffy (1938) described the growth, expressed as length, of virtually any living organism. The model is here extended to include the variation between individuals in a batch. Using this extended model, fruit size and its variation can be predicted, using measurements of a large number of fruit at a single point during early development. The diameter of 200 tomatoes was measured 15 days after full bloom (DAFB). Using the density function derived from the extended von Bertalanffy model, and applying prior knowledge of some of the model parameters, the variation in size at harvest could be predicted. Validation of the results was obtained by comparing the predicted sizes with the diameters of the same tomatoes at harvest.
Proceedings of the International Conference “Environmentally friendly and safe technologies for q... more Proceedings of the International Conference “Environmentally friendly and safe technologies for quality of fruit and vegetables”, held in Universidade do Algarve, Faro, Portugal, on January 14-16, 2009. This Conference was a join activity with COST Action 924.The colour of apples (flesh colour or skin colour) was assessed using the same individual apples repeatedly in time at three different locations, in several seasons for five different cultivars. Two experiments were conducted in the orchard, one experiment during postharvest storage. The same logistic model was applied to analyse the data, separate for each location and cultivar. Non linear mixed effects regression analysis allows to extract not only information on the kinetic parameters like reaction rate constant and potential greenness, but also on the variation present in the data. The rate constant of the decolouration process was found to be largely the same for all combinations (with one exception). The variation in biological shift factor, as an expression for maturity, seems to be independent of orchard location and only slightly dependent on orchard management procedures. The main differences observed are in the potential greenness of the apples (colmin) that vary considerably between successive seasons and between cultivars. The applied technology provides the necessary tools to analyse the effects of season and orchard management, for all locations in the study. It opens wide alleys to investigate more dedicated the effects of weather, season, management and orchard location in growing apples with a constant quality (colour) over the seasons, locations and management procedures
The fruits of four different plum cultivars 'Cacanska lepotica', 'Valor', 'St... more The fruits of four different plum cultivars 'Cacanska lepotica', 'Valor', 'Stanley', and 'Tophit' were analysed for antioxidant activity, which was evaluated in plum extracts using ABTS assay. The results obtained showed that the antioxidant activity depended on the cultivar. The highest antioxidant activity was estimated in ‘Valor’ plums (18.6 μmol of Trolox equivalent (TE)/g of fresh weight (FW)), followed by cultivars 'Cacanska lepotica' (12.8 μmol TE/g FW) and 'Stanley' (11.4 μmol TE/g FW), whilst cultivar 'Tophit' showed the lowest value (10.8 μmol TE/g FW).
In this study, we focused on the possibility of forecasting the development of skin color in appl... more In this study, we focused on the possibility of forecasting the development of skin color in apples on the basis of weather forecast by using a machine learning methods. We used supervised learning and generated models via the use of six decision trees. The purpose of the research was to build models that would allow for in-practice-acceptable accuracy in the prediction of the development of fruit skin color (especial a colour parameter a*), for three apple varieties. For cv. ‘Gala, Brookfield’, the most accurate models were generated by using decision tree J48 (89.13% accuracy). For late ripening cv. ‘Fuji, Kiku 8’ and cv. ‘Braeburn, Maririred’, the most accurate model was obtained by using decision tree LMT (91.73 and 96.65% accuracy). The data confirm that the applicability of predictive models strongly depends on the accuracy of weather forecasts. In regard to the seven-day weather forecast, which was used for expert models, the accuracy of the models was, on average, reduced by 10.73%.
Abstract Size is an important property of all fruit as it determines, together with crop load, fr... more Abstract Size is an important property of all fruit as it determines, together with crop load, fruit yield. The aim of this study is to model the increase in fruit size during cell expansion based on diameter or length and to predict fruit size and volume, including the variation in size and volume, at harvest. The size of individual fruit during growth of fruit (four apple, two tomato and six pepper cultivars) was measured from early fruit set until harvest at several seasons. Size data were evaluated as diameter and length using the von Bertalanffy growth model, adapted to include the variation in size between individuals and the effect of growing temperature. The adapted von Bertalanffy model describes the increase in diameter and length and their variation. For any fruit type, size increased along the same generic growth model. A single stochastic variable, the biological shift factor, was sufficient to describe the variation in development time, initial size and maximum size. For all batches the percentage variation explained for were well over 93% with growth rate constants similar per species and only a minor effect of growing temperature. Prediction of the maximum size distribution based on measurements half way the cell expansion period is explored and discussed. Size and its distribution can be predicted based on a single measuring point in time but with two or three points in time the prediction system becomes more robust.
Biological variation is omnipresent in nature. It contains useful information that is neglected b... more Biological variation is omnipresent in nature. It contains useful information that is neglected by the usually applied statistical procedures. To extract this information special procedures have to be applied. Biological variation is seen in properties (e.g. size, colour, firmness), but the underlying issue is almost always to the variation in development or maturity in a batch of individuals generated by small scale environmental differences. The principles of assessing biological variation in batches of individuals are explained without putting emphasis on mathematical details. Obtained explained parts increase from about 60 to 80 % for the usual approach to 95 when the biological variation is taken into account. When technical variation or measuring error is small even 99 % can be achieved. The benefit of the presented technology is highlighted based on a number of already published studies covering the colour of apples during growth and storage and the firmness of cut tomatoes d...
Sažetak U voćarskom centru Maribor -Gačnik u 2010. godini smo proučavali razvoj pojedinih paramet... more Sažetak U voćarskom centru Maribor -Gačnik u 2010. godini smo proučavali razvoj pojedinih parametara zrelosti i kvalitete ploda šljive Prunus domestica L. U pokusu su bile sorte šljive Valor i Stanley. Cilj istraživanja bio je utvrditi optimalno vrijeme berbe za pojedine sorte šljive i odnose između pojedinih parametara zrelosti i kvalitete. Eksperimentalni rezultati su pokazali da boja kao parametar kvalitete i zrelosti kod različitih sorti šljiva nije dobar pokazatelj optimalnog vremena berbe, jer se u godini istraživanja boja kožice ploda kod sorte Valor razvila 17, a kod sorte Stanley 10 dana prije konzumnog dospijeća plodova utvrđenog drugim parametrima kakvoće. Ključne riječi: šljiva, zrelost, boja kožice Plum -the issue of harvest date Abstract At Fruit growing Centre Maribor -Gačnik in 2010 we investigated the development of certain parameters of maturity and quality of plum (Prunus domestica L.). In the experiment were included plum cultivar 'Valor' and 'Stanley...
Anti-hail nets for the production of apples has become a normally action for a new or update an o... more Anti-hail nets for the production of apples has become a normally action for a new or update an old apple orchard. In 2007 and 2008, the development of quality and maturity parameters of cv. 'Gala Brookfield' and ‘Fuji Kiku 8' apples grafted on M9 were studied in the Fruit growing centre Maribor-Gačnik as a factor of being grown under a blackhail net. The results showed that when grown under the black hail net fruit of both cultivars reach a higher mean mass, lower soluble solids content (0.6 to 1 ° Brix), and lower starch index, while no effect of the black hail net was detected on fruit flesh firmness and yield.
ABSTRACT The purpose of this study was to evaluate the contribution of extractable antioxidants a... more ABSTRACT The purpose of this study was to evaluate the contribution of extractable antioxidants and non-extractable phenolics to the total antioxidant activity (TAA) of plums. Therefore, the antioxidant activity was determined (ABTS assay) in aqueous–organic extracts, as well as in the extraction residues which were a subject of two different acidic treatments to release hydrolysable tannins and non-extractable proanthocyanidins (NEPA). In addition, the changes in TAA during the last week of ripening were investigated. Extractable antioxidants contributed less than 18% to the TAA, considerably higher values of antioxidant activity were associated with hydrolysable tannins and NEPA, suggesting that the antioxidant activity of plums may be underestimated in the literature. The ripening resulted in an increase of TAA up to 38% in excess of the value determined on the first sampling date. TAA showed a similar pattern over the ripening period for all cultivars studied.
Samples were taken from apple flesh while at the tree ('Gala' and 'Pinova') using... more Samples were taken from apple flesh while at the tree ('Gala' and 'Pinova') using a biopsy sampling system. After sampling the wound was closed with vaseline, which prevented wound responses. Samples were taken at different times over the circumference of the apples (at about 70 above the equator) to monitor the spatiotemporal distribution of acids (malic, citric, fumaric) and sugars (glucose, fructose and sucrose). At the same time the skin colour was assessed with a Minolta colour meter at the same location. The distribution over the circumference of the apples revealed for both cultivars a sinusoidal pattern for all colour aspects and for citric acid, while only fructose in 'Gala' showed a clear sinusoidal pattern. For all other variables measured, the pattern was only faint, with a low amplitude. Although the system is still prone to a large measuring error, biopsy sampling is a powerful tool to study the spatio-temporal distribution of taste components.
Traditionally, crop load and fruit yield from previous seasons are used as indicators for predict... more Traditionally, crop load and fruit yield from previous seasons are used as indicators for prediction of fruit size. Disregarding the inevitable biological variation between fruit, von Bertalanffy (1938) described the growth, expressed as length, of virtually any living organism. The model is here extended to include the variation between individuals in a batch. Using this extended model, fruit size and its variation can be predicted, using measurements of a large number of fruit at a single point during early development. The diameter of 200 tomatoes was measured 15 days after full bloom (DAFB). Using the density function derived from the extended von Bertalanffy model, and applying prior knowledge of some of the model parameters, the variation in size at harvest could be predicted. Validation of the results was obtained by comparing the predicted sizes with the diameters of the same tomatoes at harvest.
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