This time of year we see the first of the European New Season Lemons from Spain and Sicily. After a few months of Southern Hemisphere fruit it is great to get fruit that is grown a little closer to home however there is one small problem and that is the colour, these early fruit are green.
In most of our minds lemons are yellow (and while we are on the subject limes are green) however this is not always the case but just what we are used to, (some varieties of limes turn yellow when ripe). We have even taken the popular names for these two fruit and attached them to colours, lemon and lime mean yellow and green to us all.
Lemon trees themselves are quite different to how most of us imagine fruit to grow, some varieties like the Femminello, which is Sicily’s most common lemon variety, are continuously blooming and in the correct conditions will blossom five times in a single year with each flowering producing its own fruit. From a fruit production point of view this is what gives us these early Verdelli lemons (they come mainly from a forced flowering the previous July – August).
So why are these lemons green and the next fruit, the Primofiore, more yellow, well it all comes down to temperature. As summer gives way to autumn the days and nights get colder but more importantly the temperature differential between day and night also gets greater. This temperature differential essentially shocks the fruit into turning yellow (there are of course all sorts of clever chemical processes taking place including chlorophyll in the fruit). Many people believe that a green lemon is not ripe but this is not necessarily true, often there is little difference in terms of juice and acidity levels (taste) of green and yellow fruit.
It is possible for us to replicate this natural process, some growers with the green fruit picked have been known to place the fruit in a fridge and then in a warmer warehouse. Repeating this process several times over a few days will cause the fruit to become more yellow. The ‘gassing’ of the fruit using ethylene along with careful temperature and humidity control will also de-green lemons however this is not a process that is generally used with organic fruit.