Pretreatment of the Leaves of Ethiopian Cassava (Manihot esculenta Crantz) Varieties: Effect of Blanching on the Quality of Dried Cassava Leaves

Abstract

The aim of this work was to study the effect of blanching and drying on the quality of four Ethiopian cassava varieties (Chichu, Hawassa-4, Quelle, and Kello). Cassava leaves were subjected to blanching at 100 °C in plain water, 0.2% NaHCO₃, and 0.4% NaHCO₃ for five minutes. Cassava leaves without blanching were considered as a control. The drying temperature was set at 60 °C with a constant air velocity of 0.14 ms⁻¹. A high reduction in vitamin C (95.6% in Chichu, 95.0% in Hawassa-4, 94.9% in Quelle, and 94.4% in Kello) was noticed in leaves blanched in the 0.4% NaHCO₃ solution. After blanching, the reduction in the ash content was higher for those blanched in plain water. The crude fiber and protein content were improved by blanching. Blanching in clear water was more effective among the different solutions in reducing the cyanide content in the leaves of Kello, Quelle, and Chichu by 51, 33, and 60%, respectively. While for Hawassa-4, the reduction was higher (47%) with the 0.2%NaHCO₃ solution. After blanching, the h° values decreased, while a*, b*, and c* increased. Plain water blanching resulted in a better nutritional quality, while Hawassa-4 exhibited the best nutritional value among the four varieties.

1. Introduction

In Ethiopia, cassava was introduced in the 1960s but was not considered as a food crop until 1984 [1]. It is locally known as the Yenchet Boye, Mita Boye, Mogo, and Furno tree, and has been mainly cultivated by small-scale farmers on small plots of land [2]. It serves as a food security crop and a source of household income in different parts of the country; however, it is consumed more in the southern region of the country [3,4]. Even though the consumption of cassava leaves has been recognized in different parts of the world for many decades, it is not used as a food in Ethiopia [5]. Cassava is mainly produced in Ethiopia for its tubers, which are boiled for direct consumption or used to produce flour. The flour is used to produce composite flours for the preparation of bread and Injera [6,7]. The use of leaves like cassava leaves as a vegetable has been limited due to the high level of anti-nutritional factors (oxalates, nitrates, tannins, and phytates) and cyanide in the leaves [8].

In other countries, cassava leaves are traditionally prepared by pounding or chopping, fermentation for a day or two, or by boiling them for several hours to reduce the cyanide level [9]. Different experiments are also done to evaluate the different processing mechanisms including cooking, fermentation [10], soaking [11] the addition of 0.4% sodium bicarbonate (NaHCO₃), enzymatic and ultrasonic treatments [12] and drying [13]. For varieties with a high initial cyanogen glucoside content, drying alone is not an efficient method to detoxify cassava leaves [14]. To facilitate the detoxification process, cassava leaves can be processed by drying combined with pounding [15], fermentation, blanching [16], and hot water cooking [17]. This also helps to reduce the anti-nutritional content and results in a better taste and texture of the end products.

One of the most important pretreatment processes used in food preparation and preservation is blanching [18]. It is used to inactivate enzymes, increase the dehydration rate, and reduce the microbial load [19,20]. To select a suitable blanching method, it is important to understand the different temperatures, duration times, the physical and chemical properties of the products, and the effect of different technologies, as these have a significant impact on the quality of the final products [18,19,21]. Due to the variations of the properties among different vegetables, no single blanching technology can be effectively applied to all products [19,21]. Blanching leads to a better retention of protein, dietary fiber, and a higher fat content [22,23]. Green leafy vegetables are a rich source of vitamins, minerals, polyphenols, flavonoids, and antioxidants. Pre-treatment by blanching before the drying process helps to maintain the color quality of leaves with high chlorophyll contents [24]. On the other hand, drying can cause an increase in the concentration of nutrients [25]. Having a high nutritional and mineral value, cassava leaves can be used as leafy vegetables after blanching [26]. For many leaves and vegetables, other blanching solutions besides pure water are used before drying, e.g., NaHCO₃ [27]. Adding NaHCO₃ in cassava leaf processing has been practiced in some countries [28]. This is believed to have an impact on the pH content and facilitates the spontaneous decomposition of acetone cyanohydrin [12].

The blanching and drying of cassava leaves and the effect it has on the nutritional and antinutritional content of the final product can play a role in their acceptance as a potential alternative food source. An additional study on the processing of cassava leaves can play a great role to ensure the nutritional quality and safety of the products for human consumption. With this in mind, studies targeting the reduction of cyanide and the maintenance of the nutritional content of processed cassava leaves are needed [15]. Even though the consumption of cassava leaves as a vegetable has not yet been established in Ethiopia, recent research focused on the effect of different processing methods, but only two varieties were investigated [5,29]. The consumption of cassava leaves in Ethiopia can play a role to close the malnutrition gap in the country. Therefore, this study investigated the differences in the nutrient and antinutrient composition of the dried leaves of four Ethiopian cassava cultivars released by research centers and how they are affected by different blanching methods.

2. Materials and Methods

2.1. Material

To cultivate cassava plants, stem cuttings of four varieties (Chichu, Hawassa-4, Quelle, and Kello) were brought from Hawassa Agricultural Research Center, in Hawassa, Ethiopia, in compliance with the applicable export and import regulations, and were planted in a greenhouse at the University of Hohenheim. Six months after planting, leaves with petioles were harvested by hand from each variety. The leaves were brought to the laboratory on the day of harvest and the petioles were removed.

2.2. Methods

2.2.1. Sample Preparation

Cassava leaves (100 g for each sample run) were subjected to blanching at 100 °C with 300 mL of plain water, 0.2% NaHCO₃, and 0.4% NaHCO₃ for five minutes and immediately cooled down under running water to stop further cooking. These conditions were set based on previous suggestions for cassava processing and blanching [9,12,30]. Cassava leaves without blanching were considered as the control. The blanched leaves were left at room temperature on the drying tray for 30 min to allow the excess water to dissipate. The cyanide, dry matter, color, and vitamin C content of the samples were measured before and after blanching. The drying temperature was set at 60 °C with a constant air velocity of 0.14 m/s. The experiments were conducted in three independent runs. The dryer was preheated for 1 h to the set temperature before the sample trays were loaded. A 100 g sample was dispersed uniformly on the tray and the trays were placed in a cabinet drier (HT 15, Innotech Ingenieursgesellschaft mbH, Altdorf, Germany) in a randomized order. During drying, the samples were weighed over 30 min intervals to monitor water loss until a constant mass was obtained. The dried samples were triturated in a blender (Thermomix TM5, Vorwerk, Cloyes, France) and packed in aluminium foil bags. The samples were stored at −20 °C until the chemical analyses were performed.

2.2.2. Chemical Analysis

All chemical analyses were conducted in triplicate for each sample run. In the study, picric acid and linamarin (Sigma-Aldrich St. Louis, MO, USA), sodium carbonate, sodium phosphate, sulfuric acid, sodium hydroxide, L-ascorbic acid (VWR chemicals, Leuven, Belgium), ammonium dihydrogen phosphate, metaphosphoric acid, orthophosphoric acid, and perchloric acid were purchased from Merck (Darmstadt, Germany). All chemicals and reagents used were of analytical grade and were used following each method described below.

The moisture content was measured according to Association of Official Analytical Chemists (AOAC) [31] and the ash content was measured by placing the oven-dried samples in a muffle furnace, as described in AOAC [31]. The total cyanide was measured after blanching and drying using the picrate paper kits method as described by Bradbury, et al. [32]. Linamarase was isolated following the method described by Haque and Bradbury [33].

Vitamin C analysis was determined after blanching and drying according to the method of Valente, et al. [34] by using High-performance liquid chromatography HPLC (Shimadzu, Kyoto, Japan). Cassava leaf (1 g of fresh or 0.5 g of dried) samples were placed in a small mortar and 5 mL of extraction solution, 10% (w/v) perchloric acid with 1% (w/v) meta-phosphoric acid, were added. The samples were crushed for 2 min, then 15 mL of extraction solution were added, and the mixture was left standing for 10 min. The samples were centrifuged (Sorvall RC6 superspeed centrifuge, Kendro Co., Hanau, Germany) for 10 min at 4 °C at a speed of 15,000 rpm and were then filtered through a 0.45 µm Nylon membrane. The standard curve was prepared from L-ascorbic acid (Chem-supply Pty Ltd., Port Adelaide Enfield, Australia) diluted with the mobile phase (Figure A1). The HPLC peaks were separated by 250 × 4.6 mm columns Luna 5u C18(2) 100A (Phenomenex, Torrance, CA, USA). The mobile phase was 20 mM of ammonium dihydrogen phosphate mixed with 0.015% (w/v) m-phosphoric acid in HPLC water that was adjusted to a pH of 3.5 with 10 mol⁻¹ L of NaOH. The mobile phase was set at a flow rate of 0.6 mL per min and ran constantly for 20 min. The quantification of the ascorbic acid components was performed at 254 nm.

The crude protein content was analysed by the Kjeldahl analysis system (Vapodest 500, C. Gerhardt GmbH & Co. KG, Königswinter, Germany). The crude fiber content of the samples was measured following the method described by the AOAC [31] official method 962.09 using an automated fiber analysis system (FibreBag Analysis System FBS6, Gerhardt GmbH & Co. KG., Königswinter, Germany).

The CIELAB values including darkness/lightness (L*), red-green color (a*), and yellow-blue color (b*) values of dried samples were measured using a color meter (CM-600d Spectrophotometer, Konica Minolta, Tokyo, Japan). The hue value (h°) and chroma (C*) were calculated as described by Mclellan, et al. [35] as indicated below:

$$h^{\circ }={tan}^{-1}\left(\frac{b^{*}}{a^{*}}\right)$$

(1)

$$C^{*}=\sqrt{(b^{*2}+a^{*2})}$$

(2)

The total color changes with respect to dried untreated leaves (ΔE) were calculated as described by Sledz, et al. [36] as follows:

$$\Delta E=\sqrt{\Delta L^{*2}+\Delta a^{*2}+\Delta b^{*2}}$$

(3)

2.3. Statistical Analysis

The analysis of variance and Tukey test were performed to compare means of values in fresh, blanched, and dried cassava leaves. The experiments were conducted in three independent runs. The statistical analysis was conducted using statistical analysis software (SAS) (version 9.4, SAS Institute Inc., Cary, NC, USA).

3. Results and Discussion

The initial moisture content of fresh cassava leaves before drying was 81.1 ± 0.6%, 77.8 ± 0.9%, 78.9 ± 0.8%, and 78.3 ± 0.1% for Chichu, Hawassa-4, Quelle, and Kello, respectively. After blanching, the moisture content of the leaves increased on average by 10%. During drying, the moisture content of the fresh leaves (control) reduced continuously until a constant moisture content was established for Chichu (5.3 ± 0.2), Hawassa-4 (5.4 ± 0.1), Quelle (5.9 ± 0.3), and Kello (4.9 ± 0.3). The moisture loss was initially very rapid, while the evaporation rate decreased with increasing drying time. It took 4 h for the control and 5 h for the blanched leaves to reach a constant moisture content. The initial moisture content of the samples had an impact on the time to reach a constant value.

3.1. Cyanide Content

Blanching in plain water was effective among the different solutions in reducing cyanide content in the leaves of Kello, Quelle, and Chichu by 51, 33, and 60%, respectively. While for the Hawassa-4, the reduction was higher (47%) with the 0.2% NaHCO₃ solution (Figure 1a). After blanching and drying, the impact on cyanide was higher in the Chichu variety. The reduction of cyanide content caused by adding NaHCO₃ to the blanching solutions was lower than for plain water, due to the change in pH. This influences the stability of linamarase enzymes, which are important in the degradation of linamarin to cyanohydrin that occurs at a pH of 5.5–7.0 [37,38,39]. The stabilization of linamarase is an essential step for cyanide detoxification in cassava leaves [40]. The reduction of cyanide in the fresh leaves after drying was higher than for the blanched leaves. This is caused by the high temperature used in the blanching process, which is higher than the optimum temperature for linamarase activity (55 °C) [12]. The reduction in cyanide in this research was lower than reported by Terefe, Omwamba, and Nduko [29] for the processing of cassava leaves by fermentation (97%) and by Waluchio [16] for the pounding of cassava leaves combined with boiling (83%), solar drying with boiling (72%) and fermentation with boiling (63%). The effect of adding NaHCO₃ to the blanching solution did not have a positive effect on reducing the cyanide content and this result contradicts the outcome of previous recommendations [12]. Regardless of the blanching and drying conditions, the cyanide content of the Kello remained the highest among the four varieties (Figure 1b). A comparison done previously between the varieties of Quelle and Kello resulted in a higher amount of cyanide in the Quelle [41]. This variation might be due to the different growing locations [42]. The cyanide content of all the varieties was higher than reported in other countries [43,44]. The cyanide content in the fresh leaves of the current study can be classified as low compared to other cassava genotypes [45].

3.2. Nutritional Content

3.2.1. Vitamin C

Vitamin C is highly heat and pH-sensitive to different leaf processing methods, including blanching [46,47,48]. Due to the instability of vitamin C, one of the highest nutritional losses in cassava leaf processing is that of vitamin C. In the current study, the control of Hawassa-4 had the highest amount in vitamin C among the four varieties used in this study. The highest reduction (95.6% in Chichu, 95.0% in Hawassa-4, 94.9% in Quelle, and 94.4% in Kello) in vitamin C was noticed when the leaves were blanched in water with 0.4% NaHCO₃ (Figure 1c). The impact of drying after blanching on the vitamin C content was not significant in comparison to the blanching process (Figure 1d). The pH of the plain water used for blanching was 6.2 whereas the levels for 0.2% NaHCO₃ and 0.4% NaHCO₃ were 8.77 and 8.82, respectively. Due to the pH variation in the blanching solutions, the vitamin C loss in the leaves blanched with plain water was lower than for the other two blanching solutions. The effect of blanching on the vitamin C content was similar to the blanching of sweet potato leaves for 2 min, which resulted in the total loss of vitamin C [49] while a loss of more than 50% was found in Moringa oleifera leaves [50]. The vitamin C content of all cassava leaf varieties in this study was higher than reported by da Silva Santos, Requião Silva, Minho, Brandão, Pinto dos Santos, Carvalho dos Santos, Lopes Silva, and Lopes dos Santos [10].

3.2.2. Ash Content

After blanching, the reduction in ash content was higher in the trials with plain water for all varieties used in this study. This was caused by the leaching process of the minerals in the leaves [51]. Adding NaHCO₃ to the blanching solution had a positive impact on the reduction of the ash content (Figure 1e,f). A similar trend was observed for the ash content of beetroot leaves after drying [52]. The reduction in plain water was high and this was similar to previous research done for other cassava varieties [26].

3.2.3. Protein Content

From a preliminary experiment, it was found that the crude protein and fiber content of cassava leaves during blanching before drying was insignificant. After drying the blanched leaves, the protein content of all the cassava varieties was not significantly affected by the different blanching solutions, but was improved by the blanching process (Figure 1g). Results from this study are similar to those reported by Awoyinka, Abegunde, and Adewusi [9] for cassava leaves and Pawase, et al. [53] for drumstick leaves. This might have been caused by the losses of sugars, minerals, and vitamins to the blanching water, resulting in the changes in the total solids and an increase in protein on a dry basis [54].

3.2.4. Crude Fiber Content

The crude fiber content in the leaves increased for all varieties after blanching (Figure 1h). This result is similar to that reported by other authors for cassava leaves and other leafy vegetables [52] and contrary to the report made by Udoetok and Uffia [26]. The loss of dry matter plays a role in the increase in crude fiber in the blanched dry leaves [55].

3.3. Color

The influence of color on fresh and dried food plays a significant role in the acceptability of the product by consumers. The quality of a dried product is evaluated by people based on their visual impression of the product. The negative values of a* coefficient, representing greenness, and the color saturation (chroma C) of the green leafy vegetables are crucial factors describing the quality of the leaves [36]. The results of the current study show that the different leaf pigments were significantly affected by blanching and drying compared to the fresh leaves (p < 0.05). From the four varieties, Chichu and Kello exhibited a high value for L*, b*, C*, and a lower a* value. The h° value of Hawassa-4 was the highest among the four varieties.

After blanching, the h° values were reduced while those for a*, b*, and C* increased (

Table 1. Effect of blanching and drying on the color quality of different cassava varieties.

			Blanched						Dried
Variety	Treatment		L*	a*	b*	C*	h*	ΔE	L*	a*	b*	C*	h*	ΔE
Chichu	Control		33.0 ± 0.6 a	−8.4 ± 0.1 c	11.8 ± 1.1 c	14.5 ± 0.9 b	125.4 ± 2.6 a	-	44.8 ± 1.0 a	−10.4 ± 0.4 b	23.3 ± 0.6 a	25.5 ± 0.7 a	114.0 ± 0.4 a	16.4 ± 1.1 a
	Plain water		28.3 ± 0.4 b	−4.2 ± 0.2 a	14.3 ± 0.6 ab	14.9 ± 0.7 ab	106.4 ± 0.1 c	7.0 ± 0.4 a	35.6 ± 0.6 b	−4.7 ± 0.2 a	11.9 ± 0.6 c	12.8 ± 0.6 c	111.4 ± 0.8 b	4.2 ± 0.2 b
	0.2%NaHCO3		28.1 ± 0.9 b	−7.1 ± 0.1 b	15.3 ± 1.0 a	16.9 ± 0.8 a	115.0 ± 1.9 b	6.6 ± 1.0 a	35.1 ± 0.8 b	−5.0 ± 0.1 a	12.8 ± 0.3 bc	13.8 ± 0.3 bc	111.2 ± 0.8 b	3.9 ± 0.5 b
	0.4%NaHCO3		33.3 ± 0.2 a	−4.0 ± 0.1 a	12.5 ± 0.8 bc	13.1 ± 0.7 b	107.6 ± 1.4 c	4.4 ± 0.3 b	33.7 ± 0.6 b	−5. 3 ± 0.0 a	13.3 ± 0.3 b	14.3 ± 0.3 b	111.6 ± 0.6 b	3.4 ± 0.2 c
Hawassa−4	Control		30.0 ± 0.5 a	−6.4 ± 0.2 c	7.3 ± 0.3 b	9.7 ± 0.3 b	131.2 ± 0.7 a	-	42.6 ± 0.0 a	−10.1 ± 0.2 b	24.2 ± 0.4 a	26.3 ± 0.4 a	112.6 ± 0.2 b	21.3 ± 0.6 ac
	Plain water		28.5 ± 1.2 a	−4.6 ± 0.2 ab	6.7 ± 0.2 b	8.2 ± 0.2 c	124.3 ± 1.6 b	2.6 ± 0.6 c	33.1 ± 1.0 b	−4.3 ± 0.2 a	10.7 ± 0.7 b	11.5 ± 0.7 b	111.7 ± 0.5 b	5.1 ± 1.3 b
	0.2%NaHCO3		25.0 ± 0.4 b	−4.8 ± 0.5 b	13.3 ± 1.1 a	14.2 ± 1.0 a	110.0 ± 2.6 c	8.1 ± 0.7 b	33.5 ± 0.1 b	−4.5 ± 0.2 a	8.5 ± 0.3 c	9.6 ± 0.2 c	117.9 ± 1.5 a	4.1 ± 0.5 b
	0.4%NaHCO3		23.7 ± 0.3 b	−3.9 ± 0.3 a	13.2 ± 0.2 a	13.8 ± 0.3 a	106.7 ± 0.9 c	9.0 ± 0.1 a	32.7 ± 0.6 b	−4.4 ± 0.1 a	8.0 ± 0.6 c	9.1 ± 0.5 c	119.0 ± 2.0 a	3.4 ± 0.2 c
Quelle	Control		31.9 ± 0.7 a	−6.4 ± 0.3 c	8.6 ± 0.3 c	10.7 ± 0.1 c	126.7 ± 2.0 a	-	44.6 ± 0.7 a	−10.5 ± 0.1 b	25.0 ± 0.6 a	27.1 ± 0.6 a	112.8 ± 0.5 a	21.1 ± 0.8 a
	Plain water		27.5 ± 0.5 b	−4.3 ± 0.2 ab	13.1 ± 0.4 b	13.7 ± 0.4 b	108.3 ± 0.2 b	6.6 ± 0.9 c	35.9 ± 0.8 b	−4.4 ± 0.2 a	10.7 ± 0.2 c	11.5 ± 0.2 c	112.5 ± 1.1 a	5.0 ± 1.3 b
	0.2%NaHCO3		25.8 ± 0.2 c	−3.7 ± 0.2 a	14.6 ± 1.2 ab	15.1 ± 1.2 ab	104.3 ± 1.0 c	9.0 ± 0.3 b	36.0 ± 1.4 b	−4.6 ± 0.2 a	10.5 ± 0.3 c	11.5 ± 0.3 c	113.5 ± 0.8 a	5.0 ± 1.6 b
	0.4%NaHCO3		24.7 ± 0.6 c	−4.4 ± 0.3 b	16.0 ± 0.9 a	16.6 ± 0.9 a	105.2 ± 0.2 c	10.6 ± 0.4 a	33.9 ± 0.6 b	−4.8 ± 0.0 a	13.3 ± 0.3 b	14.1 ± 0.2 b	109.7 ± 0.4 b	5.4 ± 0.6 b
Kello	Control		33.0 ± 0.8 a	−8.1 ± 0.1 c	11.0 ± 0.4 a	13.7 ± 0.3 ab	126.5 ± 1.3 b	-	45.2 ± 1.3 a	−11.9 ± 0.5 b	30.4 ± 1.9 a	32.6 ± 2.0 a	111.3 ± 0.5 b	23.3 ± 2.1 a
	Plain water		32.9 ± 0.1 a	−5.0 ± 0.4 a	11.3 ± 0.4 a	12.3 ± 0.2 b	114.1 ± 2.4 c	3.3 ± 0.5 b	34.8 ± 2.0 b	−6.3 ± 0.3 a	14.8 ± 1.2 b	16.1 ± 1.1 b	113.2 ± 2.2 ab	5.1 ± 0.7 b
	0.2%NaHCO3		30.7 ± 0.6 b	−6.5 ± 0.2 b	12.7 ± 1.2 a	14.3 ± 1.1 a	117.1 ± 2.4 c	3.5 ± 1.2 b	35.6 ± 0.2 b	−5.9 ± 0.1 a	12.5 ± 0.2 b	13.8 ± 0.2 b	115.2 ± 0.2 a	3.8 ± 0.8 c
	0.4%NaHCO3		34.2 ± 0.4 a	−6.4 ± 0.3 b	6.8 ± 0.5 b	9.3 ± 0.4 c	133.8 ± 2.3 a	4.8 ± 0.4 a	35.3 ± 0.2 b	−5.9 ± 0.1 a	12.7 ± 0.1 b	14.1 ± 0.1 b	114.9 ± 0.4 a	3.7 ± 0.7 c

* Values with the same super script letter are not significantly different from other samples within the same variety. L* —darkness/lightness, a*—red-green color, b*—yellow-blue color, h°—hue value, C*—chroma, and ΔE—total color change.

). The a* value of the dried control leaves varied from −8.3 to −6.4. This indicated that the blanched leaves were less green than fresh cassava leaves. The L* value of the dried cassava leaves ranged from 45.2 to 32.7 and the b* value from 30.4 to 8.0 depending on the variety and the blanching conditions. Higher L* and b* values were recorded in the control of Kello, whereas lower values were recorded in the Hawassa-4 treated with 0.4% NaHCO3. In the current study, the color value L* was equal and a* values were lower than those reported by Latif, et al. [56], which was caused by the different varieties used in the studies. The impact of blanching and drying on the quality of the four cassava varieties was lower than that recorded for leaves dried without blanching. These color qualities were better in all four varieties in the control group, and best in the Kello variety. Generally, a greater diversity of the a* coefficient was observed in samples dried after blanching. For these samples, blanching resulted in a greater change in leaf color, whereas the results for the control cassava leaves were comparable to those of the untreated dried sample. It can be concluded that blanching resulted in a darker color of the cassava leaf compared to the fresh one. When the total color difference (ΔE) value is higher than 2, it indicates a color alteration visible for the consumers [36]. Based on this criterion, the color of most of the dried leaves changed in relation to the fresh ones (Table 1). Pre-treatment by blanching before the drying process resulted in a better color quality than for fresh leaves, which was similar to what was reported for herbal tea [24]. The ΔE indicates the degree of change between the control and treated dried samples, not the direction of the changes. Adding sodium bicarbonate to the blanching process had an impact on the color change of the leaves after drying, while the change was the highest in the dried controls. This is similar to what was reported for other vegetable leaves [57].

4. Conclusions

This research investigated the effect of blanching on the nutritional and anti-nutritional properties of leaves from four cassava varieties. The results obtained have shown that blanching can decrease both the nutritional and anti-nutritional properties of the samples. Even though the reduction of cyanide was high, it did not reach a safe level to be recommended for human consumption. Therefore, further methods should be introduced to process leaves from Ethiopian cassava varieties to reach a safe level. The dried cassava leaves pre-treated by blanching prior to drying had a darker color, and the ΔE values were lower than the control after drying. Plain water blanching for 10 min resulted in better nutritional quality. Among the four varieties, Hawassa-4 exhibited a better nutritional value. While blanching was found to affect the nutritional properties of the samples, this did not affect the potential of the leaves to be used as leafy vegetables. Cassava leaves can be used as vegetables and in the preparation of snacks with appropriate processing methods.