By: Francisca Barros- Militza Ivelic- Jessica Rodríguez / Kimün SPA Trio
Cherry exports have increased significantly over the last 20 years, and this increase has been accompanied by an increase in supply both in the early and late seasons. Production, which in 2000 was concentrated from late November to late December, has now increased by at least 5 weeks. To achieve this goal, 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 (2022 International Cherry Market Yearbook, 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 of both production and quality in post-harvest. In the orchard, it is a variety with good yield in quantity and size, as well as being resistant to cracking when there are not excessively intense or frequent rainfall events. In post-harvest, it is a firm variety with high sugar content, parameters that are highly sought after in our most important export market (China). In addition, the variety has a low incidence of mechanical damage. It has a long pedicel (4.5 to 5 cm) which makes its harvest easier.
This is a variety of firmness over 75 durofel, reaches soluble solids over 18° brix at color 3.5 (mahogany), the caliber curve with correct load reaches proportions in SJ and higher over 40% (Avium, 2018)
So Why is it in the spotlight today? Unfortunately, there is no perfect variety and as producers and exporters we must be aware of the weaknesses of each one. In Regina there are two weaknesses that have tended to be confused, so this article tries to gather 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 confusion arises. The first is the common comment from our Asian consumers who tell us about a “bitter” flavor, 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 stage 6 (PUC Table, Color 5); additionally, the influence of the geographic 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.
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The second characteristic of flavour alteration is the presence of internal browning, which even in mild cases (Figure 3) generates a bad flavour in the fruit. This problem was observed this season in the arrivals of the Regina variety to the different markets.
Why is it the question now? 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 had to wait longer than usual for sale due to its arrival after the Chinese New Year and the logistical problems.
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, a 69% presented elapsed times, between packaging and sale, greater than 45 days (Figure 4).
So is internal browning an occasional seasonal problem? For several years, researchers have been warning 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 more intensely when the fruit is overripe and that AM technologies would not have such a clear influence in reducing the 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 among producers and a marked increase in damage as storage time is prolonged (Figure 5).
In the present bibliography, Harb (2003) indicates that the incidence of internal browning is low after 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 does indicate 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 under 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 by this variety, the cherry technical committee commissioned researcher Juan Pablo Zoffoli to carry out studies, who together with the exporter Copefrut SA released information confirming the association of damage with senescence, with maturity at harvest playing a fundamental role. In this regard, he 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 acid applications, since delaying the taking of color would imply more days between full flower and harvest and therefore would induce the harvest of fruit with a more evolved state and closer to senescence.
In this way, the work in Regina must be addressed 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, the need arises not to delay processes or shipments and to notify receivers about the need to market the fruit before 45 days, taking into account the packing date.
In the long term, further study is required of management, both in the orchard and post-harvest, which could help us reduce and/or delay the incidence and severity of this problem, since Regina undoubtedly has more strengths than weaknesses.
Literature
2022 Yearbook International Cherry Market, IQonsulting
Harb J., Streif J. and Saquet A. 2003. Impact of controlled atmospheric storage conditions on storage and consumer acceptability of sweet cherries 'Regina'. Journal of Horticultural Science and Biotechnology, 78:4, 574-579.
Villavicencio J., Zoffoli JP, 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 JP, Naranjo P., Rodríguez J., Jara A., Contreras C., Param N. 2020. Postharvest characteristics of cherries cultivar 'Regina'. Fruticola Magazine vol 42 Nº 2.
