Õunamahla kvaliteeti ja mükotoksiini patuliini teket mõjutvad tegurid

A thesis for applying for the degree of Doctor of Philosophy in Agriculture.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.Doktoritöö eesmärgiks oli välja selgitada viljelusviisi (mahe- ja tava-), õunte pressimiseelse säilitustemperatuuri (+3°C ja +9°C) ja pressimistehnoloogia (pakkpress, vesipress ja lintpress) mõju mahla mineraalelementide- ja polüfenoolide sisaldusele, sensoorsetele omadustele ning mükotoksiini patuliini sisaldusele, mis on tervisele ohtlik. Lisaks uuriti, kas füsioloogiliste häiretega (kaltsiumipuuduse laigud ja koore pruunistumine) õunad on vastuvõtlikumad rohehallitusele ja kas nendest õuntest pressitud mahl sisaldab rohkem patuliini. Kokku uuriti katsetes 53 erinevat mahla, millest üheksa sisaldasid patuliini. Doktoritöö kõige olulisem tulemus oli avastus, et füsioloogiliste häiretega õuntes võib patuliin tekkida ka siis, kui õuntel puuduvad silmaga nähtavad seenhaigustesse nakatumise tunnused. Füsioloogiliste häiretega õunad tuleks pressida mahlaks esimesel võimalusel, et vähendada õunamahla patuliiniga saastumise riski. Nendel aastatel, kui õunte koristuseelsel perioodil sajab palju vihma, on patuliini esinemise tõenäosus mahlas suurem ja tuleks kontrollida hallitustunnuseid õunte südamikes. Vanadest vähese hooldusega maheaedade õuntest pressitud mahlad sisaldasid rohkem P, K ja Mg võrreldes tava-aedadest või noortest ja hästi hooldatud maheaedadest korjatud õuntest pressitud mahladega. Maheõuntest pressitud mahladel oli ka tendents kõrgemale polüfenoolide sisaldusele, kuigi sorditi oli mõju erinev. Kui õunu säilitati enne mahla pressimist optimaalsest kõrgemal temperatuuril, vähenes maheõuntes polüfenoolide sisaldus enam kui tavaõuntes. Seetõttu ei tohiks mahla pressimiseks mõeldud õunu säilitada kõrgemal temperatuuril kui 3±2 °C. Pakkpressi mahlades oli kõige madalam ja lintpressi mahlades kõige kõrgem polüfenoolide sisaldus. Samas olid lintpressi mahlad vähem magusad, enam hapud ja kibedad ning esines kootavat toimet. Vesipressi mahladel oli kõige värskem aroom ja maitse ning mahla värvus oli kõige säravam. Nimetatud omadused lubavad eeldada, et vesipressi mahlad oleksid tarbijate poolt enam eelistatud, seega võiks väiketootjatele soovitada vesipressi kasutamist pakkpressi asemel tootmaks tervislikku ja maitsvat õunamahla. Edaspidi on eelkõige oluline uurida patuliini teket ilma visuaalsete seenhaiguste tunnusteta õuntes.Publication of this thesis is supported by the Estonian University of Life Sciences. This research was supported by Core Organic Plus Cofund project FaVOR-DeNonDe 2015–2018, Estonian Ministry of Rural Affairs and The Enterprise Estonia project EU50282

Physiological disorders affect apple susceptibility to Penicillium expansum infection and increase probability for mycotoxin patulin occurrence in apple juice

ArticlePenicillium expansum infection of apples and mycotoxin patulin (PAT) production has previously been associated with many pre- and postharvest factors other than physiological disorders. In the current study, ‘Antei’ and ‘Krameri tuviõun’ apples with and without bitter pit (BP) symptoms and ‘Talvenauding’ apples with and without superficial scald (SS) symptoms were used in order to determine if the named physiological disorders may influence susceptibility to P. expansum infection and PAT production. Apples were inoculated with 10 μL P. expansum spore suspension with the concentration of 1×105 conidia mL-1 and stored at 24 °C with relative humidity (RH) 80%. After 7 and 11 days, lesion diameters were measured, and apples were pressed into juice. PAT content was determined in pasteurized juice. Two cultivars out of three showed that in fruit with physiological disorders, Penicilllium infection and PAT production proceeded significantly faster compared to apples, which did not have physiological disorders. SS increased the risk for PAT occurrence in juice more than BP: while the juice pressed from BP–affected apples with no visual signs of fungal diseases did not contain PAT, juice pressed from apples with SS contained PAT three times above legislative limits defined by the World Health Organization (50 μg L-1)

Health-beneficial and health-threatening compounds in organic apple juice depending on processing technology

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Occurrence of mycotoxin patulin and polyphenol profile of Nordic apple juices in relation to apple cultivation system and pre-processing storage temperature

The aims of this study were to find out if organic apple juice (AJ) contained higher contents of polyphenols or patulin compared to conventional AJ, and if higher storage temperature before processing increases patulin content in juice. AJ was pressed from Estonian, Danish and Norwegian apples. Additionally, three cultivars from Estonian organic and conventional orchards were stored at 3±2 °C and 9±2 °C before processing. Patulin, polyphenol content and antioxidant capacity were determined in pasteurized juices. In 2015, 33% of conventional (n=6) and 46% of organic (n=11) juices contained patulin; two of the organic juices above the legal limit (191 and 64µg l-1). In 2016, none of the AJs contained patulin. Patulin occurrence was more affected by weather conditions two weeks before harvest than by cultivation system and apple storage temperature. Polyphenol content was higher in organic than in conventional juices and was reduced at higher apple storage temperature

Effect of storage conditions on postharvest quality of ’Liivi kuldrenett’ and ’Talvenauding’ apples

’Liivi kuldrenett’ ja ’Talvenauding’ on Eestis ühed populaarsemad ja armastatumad õunasordid. Mõlema sordi põhiprobleemiks on lühike säilivusaeg ja kiire kvaliteedilangus. Uurimuse eesmärgiks oli katsetada erinevate säilitusrežiimide mõju õunasortide ‘Liivi kuldrenett’ ja ‘Talvenauding’ säilivusele. Katsetes kasutati 6 erinevat säilitusrežiimi: kaks tava-atmosfääri-, kaks modifitseeritud atmosfääri- ja kaks kontrollitud atmosfääri režiimi. Pärast 3- ja 5–kuist säilitamist arvutati õunte säilituskadu protsentides ning määrati erinevad kvaliteedi parameetrid: viljaliha tugevus, vilja kuivaine sisaldus, mahla kuivaine sisaldus, orgaaniliste hapete sisaldus, mahla kuivaine ja orgaaniliste hapete suhe ja askorbiinhappe sisaldus. Mõlema sordi puhul osutus säilivuse ja õunte kvaliteedinäitajate osas parimaks kontrollitud atmosfäär, milles O2 sisaldus oli 2%, CO2 sisaldus 0,5%. Vaatamata headele sisemise kvaliteedi näitajatele pruunistusid sordi ’Talvenauding’ õunad pärast nädalast toatemperatuuril (18 °C) hoidmist. Tulemused näitasid, et nimetatud sordi õunte koore pruunistumine oli korrelatsioonis CO2 sisaldusega säilituskeskkonnas. Seetõttu ei ole modifitseeritud ja kontrollitud atmosfääris säilitamine sordi ’Talvenauding’ õunte jaoks sobilik. Selle sordi õunu peaks säilitama hästi ventileeritud tava-atmosfääris. Seevastu näitasid tulemused, et sobilikel O2 ja CO2 kontsentratsioonidel säilituskeskkonnas saab sordi ‘Liivi kuldrenett’ õunu säilitada nii modifitseeritud kui kontrollitud atmosfääris.’Liivi kuldrenett’ and ’Talvenauding’ are two of the most popular and loved apple cultivars in Estonia. The main problem with both apples is their postharvest quality and short shelf life. The aim of the current research was to find out the effect of different controlled and modified atmosphere storage conditions on postharvest quality of ’Liivi kuldrenett’ and ’Talvenauding’ apples. 6 different storage regimes were used: two regular atmosphere, two modified atmosphere and two controlled atmosphere regimes. After 3 and 5 months of storage, percentage of decayed apples and several quality parameters were assessed: apple flesh firmness, dry matter content, content of soluble solids, titratable acidity, the relationship between soluble solids and titratable acidity and ascorbic acid content. The best results in storability and quality parameters were obtained in apples (both cultivars) stored in controlled atmosphere (O2 2%, CO2 0,5%). Despite of good intrinsic quality parameters, ’Talvenauding’ apples were affected by superficial scald after keeping them one week in room temperature (18 °C) after storage. Results showed that superficial scald was in positive correlation with the CO2 content in storage atmosphere. Therefore modified and controlled atmosphere are not appropriate for ’Talvenauding’ apples; mentioned apples should be stored in well ventilated regular atmosphere. However, results showed, that with appropriate O2 and CO2 concentrations in storage atmosphere, ‘Liivi kuldrenett’ apples can be stored in both controlled and modified atmosphere

Consumer preferences of apples in Estonia and changes in attitudes over five years

Apple preferences of Estonian consumers (n=336 in 2007 and 332 in2012) were determined regarding apple origin, production method and different quality attributes. The aim was to find out whether apple preferences of young people raised in a capitalistic system differ from older people raised in the Soviet Unionand also to determine if and how these preferences have changed over five years. The majority of the respondents preferred domestic apples (91% and 81% in 2007 and 2012, respectively), the main motivation being food safety: domestic apples were believed to contain fewer chemical residues. Apple taste was the most important quality attribute, followed by appearance which was rated equally important as health benefits and finally, price. Young people (<25 years) were significantly more indifferent towards apple origin compared to others. However, the preference for apple taste and colour was similar in all age groups. Over the five year period surveyed, the preference for domestic and organic apples had decreased, but taste and colour preference had remained unchanged

Content of health-beneficial compounds and sensory properties of organic apple juice as affected by processing technology

Quality of cloudy organic apple juice processed by rack-and-frame press (RFP), water press (WP) or belt press (BP) was evaluated in terms of sensory properties and instrumentally measured colour, content of ascorbic acid (AsA), total soluble solids (TSS), titratable acidity (TA), polyphenols and total antioxidant capacity (TAC). ‘Cortland’, ‘Krista’, ‘Krameri tuvi~oun’ and ‘Talvenauding’ apples from Estonia were separately processed into juice by RFP, WP and BP. Juice was pasteurized at 85 �C. Pressing methods had a significant effect on juice quality. RFP-juices had the lowest TAC and content of health-beneficial polyphenols (chlorogenic acid, (�) epicatechin, (þ)catechin, procyanidin B2). BP-juices had the highest content of these polyphenols, but had the poorest sensory quality characterized as less sweet, more sour, bitter and astringent compared to other juices. RFP- and WP-juices had no differences in sweetness, sourness, astringency and bitterness, but WP-juices had the highest intensity of fresh aroma and -flavour, yellowness and clearness. Compared to RFP-juices, WP-juices had higher TAC and content of several health beneficial polyphenols, especially quercetin derivatives. Thus, WP is a good alternative to RFP in order to produce apple juice which would have higher antioxidant capacity, better appearance and higher aroma intensity

The effect of organic and conventional fruit cultivation system on mineral composition and sensory properties of cloudy apple juice

The aim was to determine the differences in mineral composition and sensory properties of cloudy apple juice depending on apple cultivation system. Three indigenous Estonian cultivars were chosen on condition that the same cultivars would be grown in organic and conventional orchards at the same geographical location. ’Krameri tuviõun’ and ’Talvenauding’ apples were harvested from old (over 30 years) low maintenance orchard and ‘Krista’ apples from 10-years old experimental orchard. 100 kg of apples per cultivar and cultivation system were stored at +3±2°C for two months and then pressed into juice using Lancman waterpress. Total soluble solids (TSS), titratable acidity (TA) and content of P, K, Ca and Mg were determined from apples and from juice. Descriptive sensory analysis of apple juice was carried out by a trained sensory panel. ’Krameri tuviõun’ and ’Talvenauding’ apples and respective juices from old organic orchard had significantly higher content of P, K and Mg compared to the conventional counterparts. Mineral composition of ’Krista’ apples from younger well- maintained organic orchard and respective juice was not significantly different from conventional ones except for P concentration, which was higher compared to conventional apples. Organic apples from old orchard had higher TSS compared to conventional ones, but this difference was no more significant in juice. Sensory properties of juices were most of all affected by cultivar: ‘Krameri tuviõun’ juice was sweeter and less sour compared to ‘Talvenauding’ and ‘Krista’. Cultivation system did not affect the sweetness, sourness as well as fresh- and apple flavour. Our results indicate that even though the old organic apple orchards do not produce high quality apples for fresh consumption, cloudy apple juice made from those apples is better source of valuable mineral elements for humans than apple juice pressed from conventional or well-maintained organic orchards

Health-beneficial and health-threatening compounds in organic apple juice depending on processing technology

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