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Effect of Air‐Drying Temperature on the Quality and Bioactive Characteristics of Dried G alega Kale ( B rassica oleracea L . var. A cephala)
Author(s) -
Oliveira Sara M.,
Ramos Inês N.,
Brandão Teresa R.S.,
Silva Cristina L.M.
Publication year - 2015
Publication title -
journal of food processing and preservation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.511
H-Index - 48
eISSN - 1745-4549
pISSN - 0145-8892
DOI - 10.1111/jfpp.12498
Subject(s) - browning , food science , chemistry , carotenoid , antioxidant capacity , horticulture , chlorophyll , water content , moisture , shelf life , air temperature , botany , antioxidant , biology , biochemistry , geotechnical engineering , organic chemistry , engineering , climatology , geology
The objective of this work was to evaluate the drying characteristics and the effect of drying temperature on the quality characteristics of G alega kale without any pretreatment. Drying times of 330, 162, 78 and 51 min provided minimal moisture contents, using temperatures of 35, 50, 70 and 85C, respectively. The L * and a * values diminished and b * increased, resulting in increasing values of chroma, total color difference and browning index, as well as decreasing values of the hue angle. A pronounced effect on the retention of total phenolic compounds and vitamin C losses ranging from 4.8 ± 9.7 to 55.5 ± 7.4% were observed. Regarding antioxidant capacity, losses from 51.7 ± 7.5 to 69.6 ± 3.7% were obtained. Chlorophyll a content decreased with increasing drying temperatures, with losses between 8.9 ± 6.7 and 35 ± 5.6%, while degradation of chlorophyll b was negligible. In conclusion, the air drying of G alega kale without any pretreatment resulted in considerable deterioration of its quality characteristics and nutritional value. Practical Applications Drying processes are often applied to preserve and increase the shelf life of vegetables. These products contain an extensive collection of phytochemicals known to provide health benefits. However, these compounds generally undergo significant degradation during drying because of their sensitivity to heat, light, oxygen, as well as to leaching phenomena. Thus, increased attention has been given to the concerns regarding the quality degradation of vegetables during drying. G alega kale was the selected vegetable as information concerning the influence of drying on the quality parameters of this vegetable is scarce. Additionally, this vegetable is known to present several healthy nutrients, but after harvest it is easily perishable. Therefore, drying could be a valuable strategy to preserve and increase the shelf life of this product. Thus, this work evaluates the impact of the drying temperature on the quality properties of Galega kale without the employment of any pretreatment.