Collecting firewood: why do we wait for the frosts?

The blackthorn (Prunus spinosa) is one of the most characteristic berries of autumn forests and fields. The dark blue, wax-coated fruits of the shrubs ripen as early as September, however, those who taste them at this time often pucker their lips in disappointment. This is because the blackthorn is still extremely sour and almost inedible at this point. Traditional folk knowledge and modern food biology studies both show that it is worth picking the blackthorn only after the first frosts. But why is this the case, and how does the cold change the properties of the fruit? The blackthorn belongs to the rose family and is a thorny shrub that can grow up to 1-3 meters tall. Its fruit is small, round, with a diameter of 1-1.5 cm, with a stone shell, bluish-black on the outside and yellowish flesh on the inside. It is widespread across most of Europe, and in Hungary, it is mainly found on forest edges, pastures, and along roads. It is considered an important wild fruit that has long ...