Abstract:
Chia leaf (Salvia hispanica L.) is an underutilized low-cost source of
nutrients. The leaf is currently not widely utilized as compared to the chia
seeds which have wide use in the food industry. The present study
investigated the effect of solar-drying and oven-drying chia leaves harvested
at different stages of growth on their nutritional and phytochemical
composition. The chia leaves were harvested at four stages of early vegetative
stage, late vegetative stage, budding stage and flowering stage. Oven drying
was done at45 ºC for 24hours, and solar dried in a solar drier until a constant
weight was achieved. The results indicated significant differences (p<0.05)
between treatments and stages of maturity. Results also showed that solar
dried had better nutritional and phytochemical retention over oven dried
chia leaves. Crude protein was highest in solar dried leaves at early
vegetative stage (FS1) 4.48%, compared to 4.44% for oven dried chia leaves.
The fiber content increased from the fresh leaf at 12.4% to high content in
solar dried leaf at the early vegetative stage at 23.33%, while oven dried
leaves had high content at the flowering stage at 22.09%. There were
minimal changes in fat content of the dried chia leaves compared to fresh
sample at 5.908%, with high fat levels noted for oven dried leaf at the early
vegetative stage (FS3) at 5.68% and solar dried leaves at 4.71% at the
budding stage. The difference in fat content could be attributed to
degradation during the drying processes. Ash content on the other hand
showed difference at different stages of growth from raw samples for both
solar- and oven dried leaves. Highest retention of phenolic content was
recorded at 147.62 mg/GAE for solar dried leaves at the budding stage (FS3).
However, oven dried leaf samples recorded high phenolic content at 124.06
mg/GAE at the late vegetative stage. The flavonoid levels were recorded
highest for solar dried leaves at the budding stage at 299.8 mg/CE, compared
to high content for oven dried leaves at the budding stage recorded at 270.4
mg/CE. Scavenging activity was highest recorded for solar dried samples at
the budding and flowering stages at 100 µg/100g compared to oven dried
leaves at 80.85 µg/100g at the late vegetative stage. Solar drying is the
simplest and convenient low-cost technology for preserving the nutritional
quality and retention of phytochemical ranges of chia leaves which will
enhance their utilization when abundantly available.
