Nutrient composition, total phenolic content, and antioxidant activity of tropical Kundasang-grown cucumber at two growth stages

Amir Husni Mohd Shariff1*, Puteri Noor Zulaikha Megat Mohamed Abdul Wahab1, Aanada H. Jahurul1, Nurul Huda1, Nissha Bharrathi Romes2, Mona Zakaria3, Jumardi Roslan1, Roswanira Abdul Wahab2, and Fahrul Huyop2
The cucumber (Cucumis sativus L.) contains a significant amount of antioxidants, especially when harvested at the right time. The present study evaluated differences in nutrients, total phenolic content, and antioxidant activity of cucumbers grown in Kundasang, Malaysia, at the semi-ripe fruit (SR) and ripe fruit (R) maturation stages. Independent T-tests revealed significant differences (p < 0.05) between proximate analysis data for the SR and R stages. Moisture content at the SR stage (98.217 ± 0.068%) was higher than for R (97.617 ± 0.221%); similar differences were observed for the carbohydrate content (SR: 0.660 ± 0.027%, R: 0.416 ± 0.213%). The crude fiber (SR: 0.320 ± 0.012%, R: 0.576 ± 0.083%), crude fat (SR: 0.039 ± 0.004%, R: 0.317 ± 0.019%), ash (SR: 0.422 ± 0.366%), and crude protein (SR: 0.418 ± 0.018%, R: 0.651 ± 0.069%) contents showed that the results for the R stage were greater than for SR. Individual elements in the SR and R fruit significantly differ (p < 0.05), except for Se. However, Mo was undetected at both maturation stages. Results revealed that the R stage had a higher mineral content (mg 100 g-1) for Ca (SR: 10.311 ± 0.096, R: 14.076 ± 0.094), Mg (SR: 8.334 ± 0.088, R: 13.354 ± 0.089), Al (SR: 0.468 ± 0.009, R: 1.746 ± 0.019), and Fe (SR: 0.127 ± 0.002, R: 0.280 ± 0.002), whereas the SR stage had a lower Cu content (SR: 0.037 ± 0, R: 0.058 ± 0). The phenolic content (mg g-1 GAE) at the SR stage (352.683 ± 33.240) was higher than at the R stage (155.691 ± 17.042), and it was inversely correlated with their antioxidant activity, which was expressed in half maximal inhibitory concentration (IC50, µg mL-1) (SR: 182.247 ± 9.216, R: 160.782 ± 6.741). Hence, the nutritional benefits of cucumbers grown in Kundasang are enhanced when harvested between the SR and R maturation stages.
Keywords: Cucumis sativus, maturation stage, minerals, nutrition, proximate analysis, total phenolic content.
1Universiti Malaysia Sabah, Faculty of Food Science and Nutrition, Jalan UMS, 88400 Kota Kinabalu, Malaysia.
*Corresponding author (amir.husni@ums.edu.my).
2Universiti Teknologi Malaysia, Faculty of Science, 81310 Skudai, Johor Bahru, Malaysia.
3International Islamic University, Centre for Language and Pre-University Academic Development, Kuantan Campus, 25200, Pahang, Malaysia.