Sirvi Autor "Moor, Ulvi (advisor)" järgi
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Kirje Changes in the biochemical composition of apple (Malus domestica Borkh.) fruits depending on rootstock and calcium treatment(Eesti Maaülikool, 2013) Mainla, Leila; Karp, Kadri (advisor); Moor, Ulvi (advisor)In the Baltic States, the main goal in apple- related research has been to find out the winter hardy rootstocks and cultivars. The focus in yield quality studies has been on apple size, appearance and storability. Different in vitro and in vivo studies have shown the beneficial effect of phytochemicals, such as carotenoids, flavonoids, isoflavonoids and phenolic acids, in fruits and vegetables on human health. Therefore, the focus in yield studies has turned on apple biochemical composition, especially on polyphenol concentration and total antioxidant capacity. However, the appearance, taste and storability of apples are still important. In addition to genotype, the polyphenol concentration in apples is influenced by the geographic location of the plantation, weather condition during the vegetation period, agricultural practices (fertilization, plant protection, canopy pruning), crop load, fruit position within the canopy and fruit maturity. The influence of rootstock on polyphenol composition is less studied. At present, there are literature reports on the contents of selected apple polyphenols in a small number of cultivars. Data about phenolic content in Baltic apple cultivars is almost non-existent. Pre-harvest Ca treatment is widely used in many parts of the world mainly to reduce the incidence of physiological disorders of apples during storage. The influence of preharvest Ca treatment on apple polyphenol composition is less investigated. The aims of the study were to find out: 1) the influence of pre-harvest Ca treatment on apple mineral composition and different physiological disorders; 2) the effect of pre-harvest Ca treatment on different rootstocks on apple taste-related properties, polyphenol concentrations and total antioxidant capacity; 3) the effect of rootstocks on apple mineral composition, taste-related properties and polyphenol concentrations; 4) the influence of genotype on apple polyphenol composition. From experiments it can be concluded: 1) The Ca treatment (CaCl2 and Ca(NO3)2) did not reduce bitter pit, but reduced other physiological disorders: physiological spot and superficial scald. Last mentioned disorder correlated positively with N/Ca and Mg/Ca ratio in fruits and had a negative correlation with fruit Ca content. 2) By combining pre-harvest Ca treatment with certain rootstocks, it is possible to manipulate apple taste related properties. The pre-harvest Ca treatment (CaCl2) decreased TA and increased SSC/TA in apples. 3) Rootstocks affected mineral composition of apples: apples from trees on semi-dwarfing rootstock had higher Ca content and on dwarfing rootstock higher N content was measured. 4) The influence of rootstocks on apple taste-related properties was significant, but varied between the years and cultivars. Consistent effect appeared in ‘Valge klaarõun’: rootstock B.396 had large enough influence on apple taste-related properties to be perceived as a change in apple acidity and probably also flavor. 5) The polyphenol concentration in apple cultivars grown in Estonia is very variable. Different polyphenols have different antioxidant activity; from human health point of view it is primarily important to increase the concentration of polyphenols with higher antioxidant activity. The metabolism of phenolic compounds can be influenced by different agricultural practices, but more attention should be paid to the combined effects (e.g. pre-harvest Ca treatment and rootstock), which might be different from the influence each factor has separately. By influencing apple mineral composition, it is possible to increase the polyphenol concentration and finally, also the total antioxidant capacity (TAC) of apples. Different polyphenols were differently affected by the fruit mineral composition. Largest contributors to TAC, such as quercetin, quercitrin and quercetin galactoside, had a positive correlation with Ca and a negative correlation with N concentration in apples. In the current study, rootstock and regulation of N and Ca concentrations in apples caused almost a double increase of TAC in fruits.Kirje The effect of fertilizing and modified atmosphere storage on blueberry (Vaccinium spp) fruit quality(Estonian University of Life Sciences, 2023) Koort, Angela; Karp, Kadri (advisor); Starast, Marge (advisor); Moor, Ulvi (advisor); Institute of Agricultural and Environmental Sciences; Martinussen, Inger (opponent)There are few cultivated plants that grow well on acidic peat fields. However, blueberries (Vaccinium spp) are calcifuges that thrive in low pH and have lower Ca requirements compared to other temperate fruit crops. As a result, they are suitable for revegetating abandoned peatlands. The increase in production and consumption of organic food is one of the current trends, driven in part by consumers’ perception of organic food as being more sustainable and healthier than conventional. Since previous studies on blueberry cultivation in abandoned peatlands primarily focused on synthetic mineral fertilizers, it is important to study sustainable fertilizer strategies for organic blueberry cultivation. Revegetating abandoned peatlands with blueberries could also reduce the negative impacts of environmentally sensitive peatland areas. Blueberries are marketed as health promoting food, therefore maintaining fruit quality during postharvest storage is equally important to prolonging postharvest storage period. Extending the blueberry postharvest life through modified atmosphere storage and preserving their sensory and nutritional quality could be an option to add value to organically grown blueberries. However, there are very few postharvest studies concerning organically grown blueberries. The aims of the research were to find out the effect of: 1) different organic fertilizers on the plant growth, yield and biochemical parameters of fruits of half-highbush blueberry ‘Northblue’ under peatland conditions; 2) modified atmosphere packages on the external quality and the nutritional value of the fruits of organically grown lowbush blueberry and half–highbush blueberry ’Northblue’. Based on the results of fertilization experiments conducted on an abandoned peat field with half–highbush blueberry ‘Northblue’, the seaweed–based low nutrient fertilizer Biolan 4–1–2 could be recommended for organic production in peatland areas. It demonstrates more stable yield performance and has a lower impact on peat pH. Algomin fertilizer, which is based on marine algae Lithothamnium calcareum, increased the soil pH up to 5.2 and suppressed the plant growth during the juvenile growth stage. Organic fertilizers containing chicken manure resulted in comparable vegetative growth and yield as the plants receiving mineral fertilizer. The yearly variation in weather conditions was more important in determining fruit biochemical content than the type of fertilizer used. The application of seaweed–based organic fertilizer Biolan 4–1–2 resulted in similar total polyphenol content in fruits as observed in the mineral fertilizer treatment. The postharvest storage experiment with lowbush and half–highbush blueberry ‘Northblue’ demonstrated that the Xtend® modified atmosphere package prolonged the postharvest life of lowbush blueberries by 15 days and half-highbush blueberries by 9 days. The LDPE modified atmosphere package did not prolong the postharvest life of lowbush blueberries, but extended the postharvest life of ‘Northblue’ by 9 days. The CO2 content was significantly higher in Xtend® package compared to the LDPE at the end of the storage period. Both modified atmosphere packages had an effect on the taste–related properties of blueberries irrespectively of the taxa. By the end of the storage period, the SSC:TA ratio of the blueberries in the modified atmosphere decreased compared to both the initial value and the berries stored in a regular atmosphere. The content of anthocyanins significantly increased under all storage conditions, regardless of the taxa. The genetic differences were more important concerning fruit firmness, shrivelling, and decay. Both modified atmosphere packages had an impact on the firmness and the shrivelling, but the fruits of the half–highbush blueberry ‘Northblue’ were firmer and less shrivelled compared to the lowbush. Based on results, the Xtend® modified atmosphere package can be recommended for blueberry postharvest storage. However further studies are needed to find the metabolic differences of blueberry taxa and to match the respiration rates of the product with the permeation rates of the packages. Additionally, the use of biodegradable films should be considered in order to ensure sustainability.Kirje Factors affecting apple juice quality and mycotoxin patulin formation(Eesti Maaülikool, 2020) Heinmaa, Lagle; Moor, Ulvi (advisor); Vangdal, Eivind (advisor); Børve, Jorunn (opponent)The aim was to find out the effect of cultivation system (organic- and conventional-), apple preprocessing storage temperature (+3°C and +9°C) and juice pressing technology (rack-and-frame press, water press and belt press) on juice mineral elements, polyphenol content, sensory properties and mycotoxin patulin content. Additionally, an experiment was conducted to find out if the apples with physiological disorders (bitter pit and superficial scald) are more susceptible to blue mould rot and if the juice pressed from these apples contains more patulin. Nine studied apple juices out of 53 were contaminated with patulin. The most important outcome of the doctoral thesis was that patulin formation in disordered apples may occur even if visual signs of fungal infection are not present. To reduce the risk of patulin contamination, it is important to press the disordered apples into juice as soon as possible. Rainfall during two weeks before harvest may increase the risk of patulin contamination in apple juice, therefore it is important to inspect apple cores for detection any fungal diseases in rainy years. Organic apple juice pressed from apples harvested from old low-maintenance orchards contained more P, K and Mg compared to the conventional juices or organic apple juices pressed from apples harvested from young well-maintained orchards. Organic apple juices tended to contain more polyphenols, but the effect was not uniform among all cultivars. Polyphenols in organic apples were more prone to degradation if apples were kept at higher than optimal storage temperatures before juice processing. Therefore, the apples for juice pressing should not be stored at higher temperature than 3±2 °C. Rack-and-frame press juices had the lowest and belt-press juices the highest content of polyphenols. Belt press juice had the poorest sensory properties characterized as less sweet, more sour, bitter and astringent compared to other juices. Water press juices had a fresher aroma and flavour and were the most yellow and brightest. The results indicate, that water press juices would be preferred by the consumers, therefore the small-scale juice producers can be advised to implement water press instead of rack-and-frame press. In further research, it would be important to study patulin formation in visually non-spoiled apples.Kirje Possibilities to Affect Antioxidant Properties of Strawberries and Some Methodical Aspects in Their Determination(Eesti Maaülikool, 2015) Tõnutare, Tõnu; Moor, Ulvi (advisor); Wojciech Szajdak, Lech (advisor)It is generally acknowledged that genotype, cultivation conditions and postharvest technologies might have an effect on some antioxidant compounds in strawberries, but the extent to which different measures impact total antioxidant capacity, is rarely reported. Also, the importance of methodological aspects in strawberry anthocyanin determination and thereafter interpreting the health-beneficial value of different cultivars is often underestimated. The aims of the thesis were: to give better insight into weaknesses of the widely used pH differential method for strawberry anthocyanin determination and to suggest a reliable procedure in order to get true results; to find out whether strawberries from commercial organic (OR) farms have higher antioxidant properties compared to fruits from commercial conventional (CONV) farms; to determine the effect of fertilizer containing phosphite anion (HPO32-) and postharvest modified atmosphere on antioxidant properties of strawberries; to identify genotypes with outstanding antioxidant properties among new strawberry cultivars bred for growing in the northern region. As a result of using different molar absorption coefficients which have previously been used in published literature, the total anthocyanin content for individual strawberry cultivars differed more than 50%. When the pH differential spectroscopic method is used, pelargonidin-3-glycoside with the ε=15600 M-1cm-1 would enable most precise estimation of total anthocyanin content in strawberries. Experiments with OR and CONV strawberries indicated that if fruits from only two production sites were studied, OR strawberries had higher total antioxidant capacity. If fruits from seven different OR and CONV farms were compared, a large variation in antioxidant compounds within both OR and CONV strawberries outplayed the effect of cultivation system. Thus, OR strawberries do not necessarily contain more antioxidants compared to CONV strawberries in Estonia. Pre-planting phosphite treatment increased strawberry fruit anthocyanins by up to 20% and ascorbic acid content by up to 40%. Postharvest modified atmosphere was effective in maintaining higher total antioxidant capacity of ‘Polka’ and ‘Honeoye’ strawberries during 5-days storage. ’Marmolada’ could be distinguished by outstanding antioxidant properties.