When winter arrives, the usual boxes full of citrus fruits. At first glance they all look the same: small, orange, fragrant. Then you open one, then another, and you realize that they change a lot. One is very sweet, another is more pungent, yet another smells of resin. But why are they so different if they look the same? In recent years the genetic studies have made it clear that a good part of these differences arise from one complicated history of crossbreeding: mandarin, pomelo and citron are the common “ancestors”, while fruits such as clementine or clementine are children and grandchildren of different combinations. This mixture explains many characteristics, but not everything. There are differences seen in the laboratory: some cultivars are more acidic, others more sugary, others still ripen more slowly and have a balance of taste all their own. Even when the juice is analyzed in detail, it shows very different flavor profiles: in mandarin they appear more intense notes and “green”, while clementine has a cleaner and more linear scent. And then there are the newer hybrids, like Tacle and Clara, which combine the sweetness of small fruits with the color and liveliness of blood oranges.
Mandarin, clementine and clementine are not the same: how to recognize them
In recent years, citrus fruits have been disassembled and reassembled at the genetic level with surgical precision. In particular, a great work published in the journal Nature showed that the majority of cultivated citrus fruits are derived from three main ancestors: mandarin (Citrus reticulata), pomelo (Citrus maxima) And cedar (Citrus medica). Everything else, i.e. sweet orange, lemon, grapefruit, clementine, clementine, comes from subsequent crossings between these three strains. What really changes between mandarins, clementines and mandarins concerns the genetic origin, the flavor and the seeds:
- Mandarin: acidic, with a more complex aroma, low limonene and higher γ-terpinene.
- Clementine: it is, in fact, a mandarin with a “touch” of pomelo. A study, published in BMC Genomicshas in fact reconstructed the entire clementine genome, showing that the clementina is the daughter of a Mediterranean mandarin and a sweet orange, which in turn, derives from repeated crossings between mandarin and pomelo. This is why the Clementine is sweeter than mandarinhas lower acidity and almost always has very few seeds. It has a higher pH, lower acidity, a sweet and “clean” taste with very high limonene, and a linear aromatic profile.
- Mandarin orange (tangor): it is a more “rustic” brother, in fact it has the same “basic” origin as the clementine (tangerine × orange), but belongs to different and more heterogeneous crosses. The result is harsher, “stronger” on the palate, often more acidic than clementines.
How they are chemically distinguished: the study of the 11 cultivars
To understand if these genetic differences are really noticeable when tasted, a group of Spanish researchers has published on Scientia Horticulturae a very large study on 11 cultivars between mandarins, clementines, tangors and hybrids. The scientists measured pH, sugars (TSS), acidity (TA) and maturation index (MI).
And the results are very clear.
As for the pH, the clementine is naturally sweeter, with a pH around 4.5while for mandarin oranges and other hybrids it was around 3.5. A lower pH means greater acidity, which is why mandarin oranges are more sour.
THE’acidity (TA) is the most obvious difference. The Ortanique mandarin orange, for example, had very high acidity, i.e 35.8 g/Lthe highest value among the fruits analyzed. Clementines and some hybrids, however, had much lower values, consistent with a sweeter and “rounder” flavor.
For the part of the sugars (TSS), clementines ranged between 12.0 and 14.4 °Brix (a unit of measurement that indicates how many sugars are present in a liquid), while hybrids were more variable (10–15.4 °Brix).
THE’maturation index (MI) it is the parameter that we perceive most on the palate and it is the relationship between sugars and acidity. Mandarin orange is sour and strong; while clementine has very high values, associated with a balanced and pleasant taste. When we say “this clementine is delicious”, we are often unconsciously reacting to a high E.
The aroma tells the truth: the study on volatile compounds
Another group of researchers published on Food Chemistry a very detailed work on 67 citrus juicesmeasuring the molecules that generate the aroma, mainly limonene and γ-terpinene. Their combination determines clearly different aromatic profiles between the various citrus fruits.
There Clementine has almost dominant limonene: in fact, limonene is present in clementine juice approximately 90% of the total aroma. This is the molecule of the “clean citrus” smell, the sweet and fresh one.
Mandarin has a more complex and resinous scent. In the Mandarin analyzed in the study the limonene drops to 66%While γ-terpinene rises up to 21%. This molecule gives a more herbaceous, spicy, “green” note. This is why mandarin has a less “sweet” and more characteristic scent. Hybrids, however, are in the middle. The aroma confirms what genetics and chemistry already said.
Modern hybrids: Tacle and Clara, “red” mandarin oranges
A study published in Journal of Agricultural and Food Chemistry analyzed two modern hybrids: Tacle And Clara, both derived from clementine × Tarocco.
These fruits combine: the sweetness and ease of use of clementine and the nutritional characteristics of blood orange. In the study it was found that in these hybrids the yield of fresh fruit juice is around 40% (with Clara reaching almost 48%, based on the collection period), the vitamin C in Clara it went up to about 77 mg/100 mLThe anthocyanins (the red pigments) are found from 0 to 2.66 mg/L during storage, while the presence of cyanidins (antioxidants) reached 37%. So this means that these fruits are technically mandarin oranges, but with a personality of their own.
