Tailoring Organic Apples by Cultivar Selection, Production System, and Post-harvest Treatment to Improve Quality and Storage Life

Abstract

<jats:p>A series of pre- and post-harvest experiments were conducted to enhance apple tree productivity and improve fruit quality and storage life by altering production system and post-harvest treatments in an organic orchard. Increasing the light distribution and carbohydrate uptake (summer pruning and covering the orchard ground with reflective textile) improved tree productivity, fruit color, content of anthocyanin, ascorbic acid, and total phenolic compounds and reduced incidence of fungal storage diseases. Optimal harvesting time could be determined from the starch index in some cultivars, whereas the Streif index [firmness (soluble solids concentration × starch hydrolysis score)<jats:sup>−1</jats:sup>] was more accurate for other cultivars. In yet others, titratable acidity and flesh firmness also produced important information. By contrast, soluble solids concentration and skin color are not useful as a result of their sensitivity to weather conditions and light intensity. Post-harvest fruit treatment with hot water (46 °C for 120 seconds) decreased fungal decay during storage in two cultivars, whereas spraying the fruit with 10% ethanol decreased fungal decay in all investigated cultivars. Optimization of storage conditions [cultivar-specific controlled atmosphere (CA) and ultra-low oxygen (ULO) storage procedures] maintained fruit quality and reduced the amount of fungal decay.</jats:p>

Chemical contents and blue mould susceptibility in Swedish-grown cider apple cultivars

“…The commonly observed decline in resistance as the fruit matures (Norelli et al, 2017) may be connected also to changes in SSC and acidity. Previous analyses of fruit from mid-to late-ripening dessert cultivars (similar to the ones used in the present study) show about 10% increase in SSC and 50% decrease in acidity from the first harvest to the last harvest four weeks later (Tahir and Nybom, 2013). In the present study, great care was taken to use fruits of the same ripening stage.…”

“…The two samples of 'Harry Masters Jersey' had 4.64 and 2.68 mg GAE g -1 , respectively. Environmental impact has a strong effect on tannin contents in dessert cultivars, as reported in orchard management trials (Tahir and Nybom, 2013), and most likely also in cider apples. Of the 7 phenolic compounds analysed in the present study, chlorogenic acid had the highest concentration.…”

Impact of harvesting time and fruit firmness on the tolerance to fungal storage diseases in an apple germplasm collection

“…4-5, indicating an early physiological and most likely pre-climacteric stage. In a previous study of 8 Swedish-grown cultivars, a significant increase in IEC (from <1 L L −1 kg −1 h −1 to >3 L L −1 .kg −1 h −1 ) was not encountered until the third or fourth harvesting week when starch values had already passed 5 (Tahir and Nybom, 2013). Thus, starch values of 4-5 are probably indicative of low and steady IEC values.…”

“…Thus, starch values of 4-5 are probably indicative of low and steady IEC values. In addition, fungal decay did not vary much between harvesting dates when early to medium-early picked fruit of the same cultivar was compared (Tahir and Nybom, 2013). Similarly, natural fungal decay remained stable from 2 weeks before optimal picking date (OPD) to OPD (Lafer, 2006).…”

“…A number of more or less labor-intensive methods for determination of maturation stage and storage potential in apple have been used, including the quick and simple starch test (Fallik et al, 2003;Jemric et al, 2006;Lafer, 2006;Villatoro et al, 2009;Llorente et al, 2012). In a previous study of storage potential in Swedish apple cultivars, correlations between starch value and internal ethylene content (IEC) were significant and of the same magnitude as the correlation between firmness and IEC, whereas both SSC and Streif index was less strongly correlated with IEC (Tahir and Nybom, 2013). These results indicate that the starch test can be a valid replacement for the more accurate but also more elaborate IEC test.…”