3.2. Sample preparation
Three kinds of berries and fruits were used; blueberries, blackberries
and a single piece of mandarin. In order to study freeze
injuries, liquid nitrogenwas applied as it allows for a short freezing
time. The freezing of blackberries and blueberries was done by
lowering the berries in liquid nitrogen such that the entire berry
was covered and subsequently waiting around 150 s until the berry
was completely frozen. One blueberry was frozen in advance of the
others and allowed to defrost before being measured. By using
quick freezing with liquid nitrogen, it can reasonable be assumed
that the different berries experienced the same freezing regardless
of size and shape and that the full volume of the berry had been
frozen.
For the piece of mandarin, the tip of the mandarin was inserted
into a few mL of liquid nitrogen allowing the freezing to spread
such that the piece ended up being partly frozen.