Oranges, Mandarin oranges and clementines start to ripen in October and can be picked until May. Thanks to cold storage facilities we can actually enjoy oranges all year round, but they are at their very best in winter when they reach optimum ripeness, making them sweeter and even more delicious.So, having orange juice for breakfast helps us get a great start to the day, giving us energy, preventing colds and strengthening our immune system, doesn’t it?Yes—and no.