Effect of Boiling and Wet Frying on Nutritional and Antinutrients Content of Traditional Vegetables Commonly Consumed in Malawi

Abstract

This study was carried out to evaluate the effects of boiling and wet frying on nutritional and antinutrients content of Amaranth hybridus, Moringa oleifera, Bidens pilosa (black jack), Corchorus olitorius (Jute mallow) and Ipomea batatas (sweet potato) leaves. The edible portions of the vegetables were either boiled or wet fried for ten minutes then dried alongside the raw vegetables under the shade. Crude fats, minerals, vitamins and antinutrients were determined in the dried materials. Wet frying increased the oil content of the vegetables by a range of 15.49% to 28.40 % and was hence associated with lower % ash and mineral contents. Wet frying significantly reduced (P≤0.05) beta-carotene in all the vegetables except in jute mallow. Boiling had no significant effect on beta-carotene in most of the vegetables. Boiling significantly reduced (P≤0.05) ascorbic acid in all the vegetables while wet frying preserved ascorbic acid in all the vegetables. Both boiling and wet frying significantly reduced (P≤0.05) oxalates in all the vegetables except in black jack. Both boiling and wet frying significantly (P≤0.05) reduced the concentration of phytates in most of the vegetables. However, boiling was more effective in reducing the amount of phytates. Boiling reduced higher concentrations of tannins in all the vegetables as compared to wet frying. Boiling was associated with better retention of minerals and beta-carotene, and greater reduction of antinutrients in most of the vegetables. Wet frying was more advantageous in retaining vitamin C. The different species showed differences in retention of various minerals and vitamins.

Impact of Processing on Nutrients and anti-Nutrients in Tubers and Leaves of Cassava (Manihot Esculenta Crantz)

“…The leaves experienced a significantly higher reduction in the elements and anti-nutrients as a result of leaching and evaporation, especially when the leaves were pounded before boiling [23,46]. The losses of phytate due to frying and boiling might be a result of thermal degradation and dissolution in water [22]. Phytate is soluble in water and relatively heat stable during normal household boiling, but experiences higher losses in industrial processing such as canning or extrusion cooking where high temperatures are used [52].…”

“…Montagnac [3] observed that fermentation is the most efficient processing method to remove phytate (85.6 %) from cassava roots. During frying and boiling, there are high losses of phytate, which might be a result of thermal degradation and dissolution in water [22]. On the other hand, Omosuli [23] reported no significant difference in the ash, protein, crude fiber, sodium, magnesium, calcium, and phosphorus content in raw and boiled cassava tubers.…”

Durasi Perebusan terhadap Kadar Zink Daun Pepaya Jepang (Cnidoscolus aconitifolius)

“…Hasil Penelitian ini didukung oleh penelitian lain. Diantaranya penelitian yang dilakukan Issa dkk menemukan bahwa merebus daun singkong dan daun kelor selama 10 menit dapat menurunkan kadar zink (Issa et al, 2019). Penelitian lain yang dilakukan Sharma & Sharma menemukan bahwa merebus brokoli, kubis brussel, dan bayam dengan menggunakan banyak air dapat menurunkan kadar zink dibandingkan dengan mengukus dan menggunakan microwave (Sharma & Sharma, 2022).…”

The Difference of Iron Level Based on the Cooking Time and Methods Applied on the Tempeh and Beef Liver: An Experimental Study

“…Hasil dari penelitian ini didapatkan bahwa merebus berpengaruh terhadap kadar zat besi pada tempe dan hati sapi (p<0,001) (tabel 1). Hasil dari penelitian ini diperkuat oleh penelitian lain yang menyatakan bahwa proses perebusan dapat menurunkan kandungan zat besi pada keong matah merah sebagai contoh kasus dari bahan makanan hewani, serta daun ubi, daun Moringa olifera, daun jute mallow, ubi, dan irish potato sebagai contoh kasus dari bahan makanan nabati (Purwaningsih et al, 2011;Ikanone dan Oyekan, 2014;Issa et al, 2020). Namun, terdapat perbedaan hasil penelitian dengan penelitian yang dilakukan pada rainbow trout yang menyatakan bahwa proses perebusan tidak memiliki efek signifi kan terhadap kadar zat besi (Khosroshahi et al, 2016).…”