2.3. Jam making
The jam recipe was similar to the one described by
Suutarinen, Honkapa¨a¨, et al. (2000), without the addition
of exogenous pectins. Frozen strawberries, approximately
150 g per jam, were mixed with sucrose and water in the
following proportion: 43.5% strawberry fruits, 38% sucrose
and 18% deionized water. The mixture was heated until
boiling for 10 min, and then 50% (w/v) citric acid was
added to a final proportion of 0.5%. Jam was equilibrated
at room temperature (22–24 C) for 1 h and then stored at
4 C for 1 week before analysis.