Oil content and composition in relation to leaf photosynthesis, leaf sugars and fruit sugars in maturing Koroneiki olives – The mannitol effect on oil

In Koroneiki olive tree, leaf photosynthesis, and sucrose, glucose, fructose and mannitol concentrations in leaves and fruit were investigated at fruit maturity index (MI) 1.1, 3.8 and 6.9, along with oil accumulation and composition, total phenolics (TP) and total antioxidant capacity (TAC) in fruit during a fully productive season in experiment 1 (I). The effect of mannitol  treatment at 50 and 100 mg L-1, applied in mid-October, on oil content and composition, TP and TAC were investigated in fruit harvested 25 d after treatment, at an average MI of 3.4, in experiment 2 (II). In I, in leaves net photosynthesis, and sucrose, glucose and fructose concentrations decreased, but mannitol increased by advancing MI. In fruit, however, concentration of all sugars decreased apart from fructose, which increased. Oil content (% DW), already high initially at MI 1.1, increased slowly thereafter, exhibiting decreases in oleic acid (OL) and increases in linoleic (LL). TP and TAC decreased at MI 3.8, remaining stable afterwards. In II, increasing mannitol concentration promoted oil accumulation and OL in oil and reduced LL slightly, indicating an acceleration of olive metabolism. Practically, mannitol could be applied to hasten the harvest of olives, so as to avoid adverse winter conditions.   The online version of this article (doi: 10.5073/JABFQ.2016.089.001) contains a supplementary file, which is available within the ARTICLE TOOLS on the right

Effects of pre- and postharvest treatments with growth regulators on olive (Olea europeae L.) fruit.: physiological and biochemical processes in relation to quality

The objective of the present study was the evaluation of the effects of different growth regulators on physiological and biochemical processes during ripening of olive fruit. The possible relations of these processes with quality attributes were also investigated. In Chapter 1, physiological and quality attributes during ripening of ‘Koroneiki’ olives were studied in two different growing years. Oil content, fatty acid profile, total and individual antioxidants (phenolic compounds and α-tocopherol) were determined along with respiration and ethylene production rates in olives harvested at different maturity indices. Positive correlations were found among the attributes determined that had similar course of changes during ripening, and vice versa, which could be also related to harvest-timing and to quality attributes. Besides, rates of leaf photosynthesis in combination with sugar concentrations in leaves and fruit were estimated. In leaves, photosynthesis (measured as CO2 assimilation rates) and stomatal conductance were stable during the period of fruit ripening. Glucose and sucrose concentrations showed a decreasing trend in both leaves and fruit. However, fructose decreased and mannitol (MAN) increased in leaves when oil accumulation occurred in fruit. The important role of MAN in oil accumulation was suggested, as also indicated by MAN treatments. In Chapter 2 and Experiment A, the effects of pre-harvest individual applications of abscisic acid (ABA), ethylene-releasing compound Ethephon (ETH) and ethylene synthesis inhibitor ReTain (active ingredient of amino-ethoxyvinyl-glycine or AVG) at various maturity states on oil content, fatty acid profile, total and individual antioxidants were determined in harvested olives during exposure at 20 °C. The main results showed that leaf and fruit drops were observed when ABA and ETH were applied at late states of maturity. During exposure at 20 °C, total phenolics (TP) and total antioxidant capacity (TAC) increased. However, the pattern of changes in individual phenolics depended on each particular compound, whereas there was no effect of exposure time on fatty acid profile. In Chapter 2 and Experiment B, the effects of pre-harvest treatments with growth regulators (1-naphthaleneacetic acid or ΝΑΑ, ΕΤΗ and ΝΑΑ + ETH) in combination with/without girdling on fruit attributes of ‘Koroneiki’ olives were investigated. Fruit were sprayed at dark green state and harvested ~1 month later. Treatments with NAA and ETH as well as girdling had no effect on peel color and respiration rates. Ethylene production rates were promoted by ETH treatments. ETH, with/without girdling affected the oil content. NAA, at a low concentration, enhanced TP and TAC values. By contrast, treatments had no consistent effect on fatty acids. In Chapter 3, the effects of post-harvest continuous ethylene application on green 'Konservolia' olives were evaluated at 20 °C for up to 10 days. In Experiment A of Chapter 3, the effects of a series of ethylene concentrations on peel color and firmness (F) were evaluated. Ethylene prevented fruit red coloration and increased firmness (F). In Experiment B, the effects of ethylene, ethylene synthesis inhibitor AVG and ethylene action inhibitors 1-methylcyclopropene (1-MCP) and silver nitrate (SN) on peel color, F and fruit respiration were evaluated. Ethylene increased F values initially, and thereafter prevented decreases in F values and respiration rates up to day 5. AVG, 1-MCP and SN exhibited contrary to ethylene effects on F and respiration rates.In Chapter 3, the Experiment C was carried out in order to explain the increased F values, as well as changes in phenolic compounds in harvested olives and in response to ethylene treatments. The effects of a continuous ethylene treatment, applied after a treatment with/without 1-MCP, on cell wall characteristics were evaluated. The results showed that the increased fruit F could be rather attributed to the wall rigidity of cells nearest the skin, as also supported by microscopic observations. Furthermore, total and individual phenolics were assessed in Experiment C. In all samples, oleuropein, TP and TAC exhibited similar pattern of changes. Fluctuations observed in the rest phenolic compounds had no consistent trend.Σκοπός της παρούσας διατριβής ήταν να μελετηθούν οι επιδράσεις ρυθμιστών αύξησης σε μεταβολές φυσιολογικών και βιοχημικών διεργασιών, κατά την ωρίμανση του ελαιόκαρπου και πιθανές συσχετίσεις των διεργασιών αυτών με ποιοτικά χαρακτηριστικά. Στο Κεφάλαιο 1 μελετηθήκαν φυσιολογικά και ποιοτικά χαρακτηριστικά κατά την ωρίμανση καρπών ‘Κορωνέικης’, σε δύο καλλιεργητικές περιόδους. Σε καρπούς διαφορετικών σταδίων ωριμότητας εκτιμήθηκαν η ελαιοπεριεκτικότητα, το προφίλ των λιπαρών οξέων, οι συνολικές και μεμονωμένες αντιοξειδωτικές ουσίες (μεμονωμένα φαινολικά συστατικά και α-τοκοφερόλη), καθώς και η ένταση της αναπνοής και η έκλυση του αιθυλενίου από τους καρπούς. Θετικές συσχετίσεις παρατηρήθηκαν μεταξύ των χαρακτηριστικών που είχαν παρόμοια τάση κατά την ωρίμανση, και αντιστρόφως. Ταυτόχρονα, εκτιμήθηκε η φωτοσυνθετική δραστηριότητα των φύλλων σε συνδυασμό με τη συγκέντρωση των σακχάρων στα φύλλα και στους καρπούς. Τα αποτελέσματα έδειξαν ότι κατά την ωρίμανση των καρπών, η φωτοσυνθετική δραστηριότητα των φύλλων, εκτιμώμενη ως πρόσληψη CO2, και η στοματική αγωγιμότητα δεν παρουσίασαν σημαντικές μεταβολές. Οι τιμές της γλυκόζης και της σακχαρόζης στα φύλλα και τους καρπούς είχαν παρόμοια πτωτική τάση κατά την ωρίμανση των καρπών. Την ίδια περίοδο που παρατηρήθηκε η αύξηση της ελαιοπεριεκτικότητας στους καρπούς, μειώθηκε η συγκέντρωση της φρουκτόζης στα φύλλα και αυξήθηκε της μαννιτόλης (MAN). Προσυλλεκτικές επεμβάσεις με ΜΑΝ υποστήριξαν το σημαντικό ρόλο της τελευταίας στη συσσώρευση του λαδιού στους καρπούς. Στο Κεφάλαιο 2 (Πείραμα Α) εκτιμήθηκαν οι επιδράσεις των προσυλλεκτικών επεμβάσεων με αψισικό οξύ (ΑΒΑ), αιθυλενοπαράγωγο Ethephon (ETH) και παρεμποδιστή σύνθεσης του αιθυλενίου ReTain (δραστική ουσία αμινο-εθοξυ-βινυλ-γλυσίνη ή AVG), σε καρπούς ‘Κορωνέικης’ διαφόρων σταδίων ωριμότητας. Οι επιδράσεις των επεμβάσεων επί της ελαιοπεριεκτικότητας, του προφίλ των λιπαρών οξέων και των ολικών και μεμονωμένων φαινολικών ουσιών εκτιμήθηκαν κατά την αποθήκευση των καρπών στους 20 οC. Τα αποτελέσματα έδειξαν ότι οι επεμβάσεις με ΑΒΑ και ΕΤΗ, στα τελευταία στάδια ωριμότητας οδήγησαν σε καρπόπτωση και φυλλόπτωση. Κατά την αποθήκευση των καρπών στους 20 οC, αυξήθηκαν οι τιμές των ολικών φαινολικών (ΤΡ) και της ολικής αντιοξειδωτικής ικανότητας (TAC). Ωστόσο, οι μεταβολές των μεμονωμένων φαινολικών συστατικών δεν ακολούθησαν κάποια συγκεκριμένη τάση. Αντίθετα, δεν παρατηρήθηκαν μεταβολές στο προφίλ των λιπαρών οξέων. Στο Πείραμα Β του Κεφαλαίου 2, μελετήθηκαν οι επιδράσεις των προσυλλεκτικών επεμβάσεων με ναφθαλινοξικό οξύ (ΝΑΑ), ΕΤΗ και του συνδυασμού ΝΑΑ και ΕΤΗ, μεμονωμένα ή σε συνδυασμό με την εφαρμογή δακτυλίωσης, σε χαρακτηριστικά καρπών ‘Κορωνέικης’. Οι επεμβάσεις πραγματοποιήθηκαν όταν οι ελιές βρίσκονταν στο στάδιο του γαλακτώματος και η εκτίμηση των επιδράσεων τους έγινε κατά τη συγκομιδή ~1 μήνα μετά. Οι επεμβάσεις με ΝΑΑ και ΕΤΗ, καθώς και η δακτυλίωση δεν άσκησαν καμία επίδραση στο χρώμα του φλοιού και στη ένταση της αναπνοής. Το ΕΤΗ αύξησε την έκλυση του ενδογενούς αιθυλενίου των καρπών. Τόσο το ΕΤΗ όσο και η δακτυλίωση επέδρασαν επί της ελαιοπεριεκτικότητας των καρπών. Το ΝΑΑ, στη χαμηλότερη συγκέντρωση, αύξησε τις τιμές των ΤΡ και της TAC. Αντίθετα, οι μεταβολές των λιπαρών οξέων δεν ακολούθησαν κάποια συγκεκριμένη τάση υπό την επίδραση των επεμβάσεων ή/και της δακτυλίωσης. Στο Κεφάλαιο 3, μελετήθηκαν οι μετασυλλεκτικές επιδράσεις του αιθυλενίου με συνεχή χειρισμό, σε θερμοκρασία 20 οC, για χρονικό διάστημα έως 10 ημέρες, σε πράσινους καρπούς ‘Κονσερβολιάς’. Η εφαρμογή αυξανόμενων συγκεντρώσεων αιθυλενίου, αποτέλεσε το Πείραμα Α του Κεφαλαίου 3, όπου παρατηρήθηκε ότι η υψηλότερη συγκέντρωση του αιθυλενίου παρεμπόδισε την ανάπτυξη του κόκκινου χρώματος στο φλοιό και αύξησε τη συνεκτικότητα (F). Στο Πείραμα Β του ίδιου κεφαλαίου, μελετήθηκαν οι μεμονωμένες επιδράσεις του αιθυλενίου, του παρεμποδιστή της σύνθεσής του AVG, καθώς και των παρεμποδιστών της δράσης του 1-μεθυλοκυκλοπροπένιο (1-MCP) και νιτρικού αργύρου, επί του χρώματος, της F και της έντασης της αναπνοής των καρπών. Το αιθυλένιο αύξησε την F, τις πρώτες ώρες του χειρισμού και διατήρησε την ένταση της αναπνοής σε σταθερά υψηλά επίπεδα μέχρι την 5η ημέρα. Οι παρεμποδιστές επέδρασαν κατά τρόπο αντίθετο του αιθυλενίου στη F και στην αναπνοή. Στο Πείραμα Γ του Κεφαλαίου 3 εξετάσθηκε η συνεχής επίδραση του αιθυλενίου, μετά από χειρισμό με ή χωρίς 1-MCP, καθώς και του συνδυασμού τους, σε επιμέρους χαρακτηριστικά του κυτταρικού τοιχώματος, με σκοπό να εξηγηθεί η αύξηση της F. Τα αποτελέσματα έδειξαν ότι η αύξηση της F μπορεί να αποδοθεί στην ενίσχυση των κυτταρικών τοιχωμάτων εγγύτερα της επιδερμίδας των καρπών. Τα αποτελέσματα υποστηρίχθηκαν και από μικροσκοπικές παρατηρήσεις. Επιπλέον, στο Πείραμα Γ, εκτιμήθηκαν οι ολικές και οι μεμονωμένες φαινολικές ουσίες. Στους καρπούς όλων των επεμβάσεων, οι τιμές των ΤΡ, της TAC και της ελευρωπαΐνης παρουσίασαν παρόμοια τάση αλλαγών. Οι διακυμάνσεις που παρατηρήθηκαν στις τιμές των υπόλοιπων φαινολικών ουσιών δεν είχαν σταθερή τάση και δεν εκτιμήθηκαν στατιστικά σημαντικές

Fruit Ripening, Antioxidants and Oil Composition in Koroneiki Olives (Olea europea L.) at Different Maturity Indices

Harvest timing of oil olives is important for oil quality. Concerning the specific features of each cultivar, physiological and quality characteristics during ripening of Koroneiki olives were investigated in two successive years, A and B, from trees on full production. In A, olives were harvested at maturity indices (MIs) 0.9, 1.4, 2.1 and 4, while in B at MIs 1.1, 3.8 and 6.9. MIs ~1, ~4 and ~7 corresponded to green, red and dark purple peel in olives, respectively. Peel color parameters (L*, h° and C*), respiration and ethylene production rates were evaluated along with phenolic compounds and total antioxidant capacity (TAC) in olives of both crop years. Additionally, oil composition and a-tocopherol content were examined in olives harvested in years A and B, respectively. During fruit development, respiration and ethylene productions rates, hydroxytyrosol concentration and linoleic acid increased, while TAC, oleuropein, luteolin-7-O-glucoside, linolenic acid and α-tocopherol values decreased. Positive correlations were found among the attributes determined in both crop years that had a similar course of change during ripening, and vice versa, which could be also related to harvest timing and to quality traits of olive products. At MI ~4, at least all determined variables corresponded to oil of high quality. Practically, an early harvest might result in an olive fruit rich in antioxidants and therefore in oil production of high quality, high stability during storage and long self-life

Fruit Ripening, Antioxidants and Oil Composition in Koroneiki Olives (<i>Olea europea</i> L.) at Different Maturity Indices

Harvest timing of oil olives is important for oil quality. Concerning the specific features of each cultivar, physiological and quality characteristics during ripening of Koroneiki olives were investigated in two successive years, A and B, from trees on full production. In A, olives were harvested at maturity indices (MIs) 0.9, 1.4, 2.1 and 4, while in B at MIs 1.1, 3.8 and 6.9. MIs ~1, ~4 and ~7 corresponded to green, red and dark purple peel in olives, respectively. Peel color parameters (L*, h° and C*), respiration and ethylene production rates were evaluated along with phenolic compounds and total antioxidant capacity (TAC) in olives of both crop years. Additionally, oil composition and a-tocopherol content were examined in olives harvested in years A and B, respectively. During fruit development, respiration and ethylene productions rates, hydroxytyrosol concentration and linoleic acid increased, while TAC, oleuropein, luteolin-7-O-glucoside, linolenic acid and α-tocopherol values decreased. Positive correlations were found among the attributes determined in both crop years that had a similar course of change during ripening, and vice versa, which could be also related to harvest timing and to quality traits of olive products. At MI ~4, at least all determined variables corresponded to oil of high quality. Practically, an early harvest might result in an olive fruit rich in antioxidants and therefore in oil production of high quality, high stability during storage and long self-life

Girdling Effects on Fruit Maturity, Kernel Quality, and Nutritional Value of Walnuts (Juglans regia L.) alongside the Effects on Leaf Physiological Characteristics

Girdling, based on the accumulation of photosynthetic products above the girdling zone, is a common technique applied to tree species to increase the yield and fruit quality. The aim of this study was to investigate the girdling effects on photosynthesis and soluble sugars (Sols) of leaves in fruiting shoots and, for the first time, on quality variables of &lsquo;Franquette&rsquo; walnuts harvested at two harvests, early and late, 43 and 84 d after treatment, respectively. Girdling was conducted on a part of four-year old branches at the onset of kernel growth. At late harvest, coinciding with commercial harvest, girdling advanced the mature fruit percentage, kernel weight, and oil content, whereas decreased kernel moisture and slightly affected the color brightness, although kernels remained with an extra light color. Advanced maturation increased linoleic acid and polyunsaturated fatty acid (PUFA) fraction in oil, whereas it decreased palmitic acid and the saturated fatty acid (SFA) fraction in oil, kernel total antioxidants, and Sols (sucrose, glucose, fructose) in kernels and leaves and leaf photosynthesis (Pn), whereas girdling had no effect on these variables. Oil rancidity remained stable throughout the experiment. Development of callus was observed on tree wounds 84 d after treatment. Conclusively, girdling enhanced the fruit maturation, resulting in higher uniformity of maturity and increased oil yield with no quality deterioration or apparent tree damage

Girdling Effects on Fruit Maturity, Kernel Quality, and Nutritional Value of Walnuts (<i>Juglans regia</i> L.) alongside the Effects on Leaf Physiological Characteristics

Girdling, based on the accumulation of photosynthetic products above the girdling zone, is a common technique applied to tree species to increase the yield and fruit quality. The aim of this study was to investigate the girdling effects on photosynthesis and soluble sugars (Sols) of leaves in fruiting shoots and, for the first time, on quality variables of ‘Franquette’ walnuts harvested at two harvests, early and late, 43 and 84 d after treatment, respectively. Girdling was conducted on a part of four-year old branches at the onset of kernel growth. At late harvest, coinciding with commercial harvest, girdling advanced the mature fruit percentage, kernel weight, and oil content, whereas decreased kernel moisture and slightly affected the color brightness, although kernels remained with an extra light color. Advanced maturation increased linoleic acid and polyunsaturated fatty acid (PUFA) fraction in oil, whereas it decreased palmitic acid and the saturated fatty acid (SFA) fraction in oil, kernel total antioxidants, and Sols (sucrose, glucose, fructose) in kernels and leaves and leaf photosynthesis (Pn), whereas girdling had no effect on these variables. Oil rancidity remained stable throughout the experiment. Development of callus was observed on tree wounds 84 d after treatment. Conclusively, girdling enhanced the fruit maturation, resulting in higher uniformity of maturity and increased oil yield with no quality deterioration or apparent tree damage

The influence of rain cover on respiration, quality attributes and storage of cherries (<i>Prunus avium</i> L.)

The effects of rain cover on tree yield, fruit cracking and quality ,of two cherry (Prunus avium L.) cultivars, ‘Adriana’ and ‘Noire de Meched’ (‘NM’), were investigated. Cherry quality was determined at harvest and after storage at 1°C in air for up to 21 d. Rates of CO2 production and O2 uptake were determined at weekly intervals during and after storage. A taste panel rated quality attributes of ‘NM’ after 14 d storage. The results showed that ‘Adriana’ was completely, but ‘NM’ moderately resistant to cracking, while covering prevented the symptom. Respiration rates showed immediate and continuous cooling requirements of all fruit. In ‘Adriana’, covering reduced weight loss during the first 7-d storage, and promoted the peel colour (PC) and total soluble solids subsequently. Under different environmental conditions, PC and total phenolics were advanced in uncovered ‘NM’ at harvest and after storage. In both cultivars, covering did not affect negatively the yield, nor did it significantly the fruit weight, firmness, titratable acidity, pH value, total antioxidant activity, stem browning and resistance to stem removal. ‘Adriana’ and ‘NM’ retained good quality for 21 and 14 d storage, respectively

Edible Coatings from Opuntia ficus-indica Cladodes Alongside Chitosan on Quality and Antioxidants in Cherries during Storage

The aim of this work was to investigate the effect of edible coatings (ECs) prepared from extracts of Opuntia ficus-indica (OFI) cladodes in comparison with a commercial chitosan formulation on the quality of &lsquo;Regina&rsquo; cherries packaged in macro-perforated bags and stored for up to 28 d (1 &deg;C, 90% RH). The coating concentrations were 25% and 50% aqueous OFI extract (approximately 0.59 and 1.18% dry matter, respectively), 1% OFI alcohol insoluble polysaccharide and 1% chitosan. The variables evaluated included weight loss (WL), respiration rates (RR), peel color, firmness, microbial decay, total antioxidants (phenolics, flavonoids, anthocyanins, antioxidant capacity), individual phenolic compounds (anthocyanins, hydroxycinnamic acids, flavan-3-O-ols), and pedicel removal force. The main results show that all coatings reduced WL and RR similarly, enhanced firmness throughout storage and antioxidants after 28 d of storage compared to the controls. Among treatments, chitosan resulted in much higher peel glossiness and firmness in comparison to OFI extracts. On day 28, all ECs resulted in higher antioxidants than controls, OFI extracts resulted in higher cyaniding-3-O-rutinoside than chitosan, while 50% OFI treatment resulted in the highest catechin concentration. Therefore, OFI extracts are promising ECs for cherry storage since they exhibited no negative effect, improved quality and extended storage life by one week compared to the controls

Preharvest Foliar Salicylic Acid Sprays Reduce Cracking of Fig Fruit at Harvest

Peel cracking and ostiole-end splitting (collectively termed cracking) are common disorders in ripe fig fruit, downgrading fruit quality and thus limiting marketability. This two-year field study addressed the possibility of alleviating cracking at harvest by two foliar salicylic acid (SA) sprays prior to harvest (8 and 5 d). Three SA concentrations (0, 1, and 2 mM) were employed in the first year, and based on the obtained results two (0 and 2 mM) in the second year. A local variety (&lsquo;Vasilika&rsquo;) with excellent organoleptic profile, and high sensitivity to cracking was evaluated. Fruit was harvested at commercial maturity. Fruit marketability was mainly based on the incidence and severity of cracking. Fruit weight, peel color, flesh total soluble solids (TSS), titratable acidity (TA), and pH were estimated for fig quality. The contents of total anthocyanins (TAN), cyanidin-3-rutinoside (c-3-rut; the major anthocyanin in fig), and the expression of four genes coding for regulatory enzymes (phenylalanine ammonia lyase, anthocyanidin synthase, UDP-flavonoid glucosyl transferase 1, and UDP-flavonoid glucosyl transferase 2) of the phenylpropanoid biosynthetic pathway were also determined in the peel. Preharvest SA application (2 mM) increased the percentage of fruit without cracking (sound fruit) by 1.4&ndash;2.6-fold, and of marketable fruit (sound and slightly cracked) by 2-fold. SA application (2 mM) was associated with increased flesh TSS and TA, as well as with decreased flesh pH and peel red coloration in stripe. The treatment (2 mM SA) decreased both TAN and c-3-rut contents, which were highly associated (r = 0.978). Responses of transcription level of the four genes to SA application varied, and did not correlate with the other variables in the study. In conclusion, SA appears to be a low-cost and environmentally-safe agent for improving fig fruit quality and marketability, and facilitates harvesting and postharvest management of figs