3.4. Textural characteristics
The textural characteristics of frozen foods, which are mainly
influenced by freezing rate, play an essential role in determining
the acceptability of these products by consumers (Krause, Miracle,
Sanders, Dean, & Drake, 2008; Zhang et al., 2007). Good quality
litchi products should present a high degree of hardness, resilience
and chewiness of the pulp (Kaushik, Kaur, & Rao, 2013). The least
changes in texture during frozen storage were observed in IF
samples. After 15 days of storage, IF samples retained 84% of
firmness, 89% of resilience and 86% of chewiness, compared to only
72%, 58% and 62%, respectively, in AF samples (Fig. 5). At the end of
storage (180 days), retention of 80% of the initial hardness, resil-
ience and chewiness were detected in IF samples, while dramatic
loss of texture (about 50%) occurred in AF samples. Most of the loss
happened during the freezing process and the first two weeks of
frozen storage. These results further indicated that IF technology
had a more notable protective effect on the natural texture of litchi
fruits after freezing and long term frozen storage compared with AF
method. This is likely due to reduction of the damaging effects of
crystallization and recrystallization on the microstructure of litchi
tissues during freezing, frozen storage and thawing by IF process-
ing. The results illustrated again the key role of the freezing rate in
maintaining the texture of frozen foods (Van Buggenhout, Tran,
Sila, Smout, & Hendrickx, 2004).