The export of cherries has had a significant increase in the last 20 years, this increase has been accompanied by expanding the offer both early and late. Production that, in 2000, was concentrated from the end of November to the end of December, today has expanded by at least 5 weeks. For this objective, the industry has had to implement a varietal replacement and expand the traditional production areas.
In the varietal replacement, Regina has turned out to be the third most planted variety, reaching a volume of 66,851 tons in the last season (Yearbook 2022 International cherry market, IQonsulting) and occupying a niche in late production with plantations in the south of the VII region. .
Why did Regina stand out from other late varieties?
There are different characteristics both productive and quality in postharvest. In the orchard it is a variety with good yields in quantity and size, as well as being resistant to splitting when there are not excessively intense or frequent rain events. In postharvest it is a firm variety with high sugar, highly desirable parameters in our most important export market (China). In addition, the variety presents a low incidence of mechanical damage. It has a long pedicel (4.5 to 5 cm) which makes it easy to harvest.
This is a variety of firmness over 75 durofel, it reaches soluble solids over 18° brix at color 3.5 (mahogany), the size curve with the correct load reaches proportions in SJ and higher over 40% (Avium, 2018).
So why is he in the spotlight today? Because unfortunately there is no perfect variety and as producers and exporters we must be attentive to the weaknesses of each one of them. In Regina there are 2 weaknesses that have tended to be confused, for which this article tries to collect information to clarify the differences between these weaknesses and guide decisions to be able to face them.
The weaknesses mentioned above are related to flavor and perhaps that is why the confusion is generated. The first is the common comment from our Asian consumers who tell us about a “bitter” flavor (or bitter in Spanish), a characteristic that is associated with orchards and when the fruit is harvested with lighter colors (Figure 1, Villavicencio and Zofolli 2021). These authors characterize this flavor as herbaceous, pointing out that its incidence is strongly related to maturity stages 3 (Figure 2; PUC Table, color 3) and 4 (PUC Table, color 3.5), decreasing both in incidence and severity towards state 6 (PUC Table, Color 5); Additionally, the influence of the geographical location of the orchards was observed. In this study, 39 volatile compounds were also analyzed, but the presence of some of them could not be related to the herbaceous flavor.
Figure 1: Incidence of bitter or herbaceous taste in different orchards with different geographic locations and states of maturity. (stage 3) bright red (UC color chart 3), (stage 4) mahogany (UC color chart 3.5) or commercial harvest, (5) dark mahogany (UC color chart 4.0°) and (6) black overripe (UC color chart 5.0). Villavicencio and Zofolli 2021.
The second characteristic in the alteration of the flavor is the presence of internal browning, which even in slight incidences (Figure 3) generates a bad flavor to the fruit. This problem is the one that was observed this season in the arrivals of the Regina variety to the different markets.
Why now is the question? In order to understand this disorder, we must be clear that this is a damage associated with the senescence of the fruit.
This season, most of the Regina variety, due to arriving after Chinese New Year and facing logistical problems, had to wait more days than usual for sale.
In this regard, data provided by San Jorge Packaging indicate that in more than 8,000 inspections of packed boxes carried out in China in this variety, 69% presented elapsed times, between packaging and sale, greater than 45 days (Figure 4).
Figure 4. Days elapsed between packaging and sale of the Regina variety, destined for China, 2021/2022 season (data provided by San Jorge Packaging).
So is internal browning an occasional seasonal problem? For several years now, researchers have warned about this problem in the Regina variety. Zoffoli et al (2020) report different incidences of damage in cherry producers and conclude that the disorder occurs with more intensity when the fruit is overripe and that AM technologies would not have such a clear influence on reducing damage (Table 1 and 2 ).
In this regard, the information generated by the authors of this article, in the 2020-2021 season, indicates different intensities between producers and a marked increase in damage as storage time is prolonged (Figure 5).
Figure 5. Variation of the Internal Browning Percentage for fruit from different producers and storage time at 0°C.
Within the present bibliography, Harb (2003) indicates that the incidence of internal browning is low at 4 weeks of storage, presenting moderate and severe damage with storage of 6 weeks. This author also indicates the low effect that controlled atmosphere technology would have on the manifestation of damage, but that very high levels of CO2 and very low O2 could increase the manifestation of damage (Table 3).
Table 3. Internal browning in Regina cherries stored in different CA conditions and stored for 6 weeks at 1ºC. The fruit is visually inspected and moderate and severe damage is recorded. Harb 2003.
Considering the problems presented in this variety, the cherry technical committee commissioned researcher Juan Pablo Zoffoli to carry out studies, who together with the exporter Copefrut S.A. released information that confirms the association of damage to senescence, with maturity at harvest playing a fundamental role. In this regard, it also sheds light on the importance of correct nutritional applications in the field, specifically Nitrogen, as well as taking care of the relationships between Potassium and Calcium, which could manifest a greater incidence of damage. On the other hand, he also recommended being cautious with gibberellic applications since delaying color taking would imply more days between full flower and harvest and therefore would lead to harvesting fruit with a more evolved state and close to senescence.
In this way, the work in Regina must be faced with short and long-term measures. In the short term, in the orchard, nutritional aspects must be taken care of, as well as avoiding over-ripeness at harvest, considering the information generated by the aforementioned researchers. On the other hand, there is a need not to delay processes or dispatches and notify recipients of the need to market the fruit within 45 days, taking into account the packing date.
In the long term, it is necessary to deepen the study of the management, both in the orchard and post-harvest, which could help us to reduce and/or delay the incidence and severity of this problem, since Regina undoubtedly presents more strength than weaknesses.
Bibliography
Yearbook 2022 International cherry market, IQonsulting
Harb J., Streif J. and Saquet A. 2003. Impact of controlled atmosphere storage conditions on storability and consumer acceptability of sweet cherries ‘Regina’ . Journal of Horticultural Science and Biotechnology, 78:4, 574-579.
Villavicencio J., Zoffoli J.P, Plotto A. and Contreras C. 2021. Aroma Compounds Are Responsible for an Herbaceous Off-Flavor in the Sweet Cherry (Prunus avium L.) cv. Regina during Fruit Development. Agronomy 11. 2020. https://www.mdpi.com/journal/agronomy
Zoffoli J.P., Naranjo P., Rodríguez J., Jara A., Contreras C., Param N. 2020. Postharvest characteristics of cherries cultivar ‘Regina’. Fruticola Magazine vol 42 No. 2.
