Standardisation of dehydration, storage and packaging of drumstick (Moringa oleifera Lam.) leaves

Abstract

Leafy vegetables are an essential part of a healthy diet, providing an affordable source of vital vitamins, minerals, and antioxidants. Among them, Moringa oleifera Lam., often called the "miracle tree," stands out for its exceptional nutritional and medicinal properties. Its leaves are rich in bioactive compounds with antioxidant, anti-inflammatory, and antimicrobial benefits, contributing to improved nutrition and addressing malnutrition, especially in rural households. However, the high moisture content of fresh Moringa leaves makes them highly perishable, necessitating effective post-harvest management to extend their shelf life. Proper dehydration techniques not only reduce spoilage but also help retain their nutritional value, ensuring year-round availability. Converting Moringa leaves into powder enhances their stability and facilitates their incorporation into value-added products. Additionally, suitable packaging and storage conditions play a crucial role in preserving quality and minimizing post-harvest losses. Despite its significance, research on optimizing postharvest handling of Moringa leaves remains limited in Kerala. Hence with this background the present study entitled “Standardisation of dehydration, storage and packaging of drumstick (Moringa oleifera Lam.) leaves” was undertaken to standardize pretreatment methods, dehydration techniques, and suitable packaging materials and storage conditions to enhance the shelf life and preserve the nutritional integrity of Moringa oleifera Lam. leaves. The study was structured into three experiments. The first experiment was to standardise the pretreatments of Moringa leaves. Fresh Moringa leaves were collected, destalked, washed, and subjected to four treatments: control (no blanching), hot water blanching (80°C for 1 min), steam blanching (1 min in a steam cooker), and microwave blanching (800 W for 30 s). Blanched leaves were rapidly cooled, shadedried, powdered, and analysed for physical and biochemical properties including recovery percentage, moisture content, crude fibre, crude fat, total protein, total ash, total carbohydrate, ascorbic acid, total chlorophyll content, total carotenoids and total phenols. The results revealed that blanching treatments significantly influenced the physical and biochemical parameters of Moringa leaves. Microwave blanching (T4) emerged as the most effective pre-treatment, yielding the highest recovery percentage (22.81%), lowest moisture content (8.48%), and maximum retention of crude fibre (13.50%), total carbohydrates (42.00%) and carotenoids (114.48 mg/100g). Steam blanching (T3) and hot water blanching (T2) also showed significant improvements in nutrient retention compared to the control (T1). The control treatment exhibited the lowest recovery (17.94%) and highest moisture content (11.64%), highlighting the importance of blanching in reducing moisture and enhancing nutrient concentration. Microwave blanching also retained higher levels of total ash (12.38%), total protein (24.23%), ascorbic acid (115.61mg/100g), and total chlorophyll (299.80%) and crude fat (7.53%), making it the best pre-treatment method. Moringa leaves blanched by microwave blanching were subjected to different dehydration methods, including shade drying (23–31°C), cabinet drying (50±5°C), microwave oven drying (60°C), and vacuum drying (35±5°C). After drying, the leaves were powdered and analysed for physical (recovery percentage), biochemical (moisture content, crude fibre, crude fat, total protein, total ash, total carbohydrate, ascorbic acid, total chlorophyll content, total carotenoids and total phenols.), mineral (Fe, Ca and K), and antioxidant properties. The results demonstrated that dehydration methods significantly influenced the physical, biochemical, mineral, and antioxidant properties of Moringa oleifera leaves. Vacuum drying (T4) resulted in the highest recovery percentage (28.23%), total carbohydrate (48.00%), total protein (26.28%), total ash (22.42%), ascorbic acid (139.02 mg/100 g), and total phenols (160.91 mg GAE/100 g), while also exhibiting the highest antioxidant activity (IC₅₀: 3.82 mg/ml). Microwave drying (T3) recorded the highest total carotenoid content (119.43 mg/100 g) and retained notable amounts of crude fat (7.42%) and iron (13.34 mg/100 g). Cabinet drying (T2) yielded the highest crude fibre (9.70%) but the lowest crude fat (5.77%) and protein content (23.33%). Shade drying (T1) retained the highest total chlorophyll (324.41 mg/100 g) and crude fat (8.69%) but had the lowest recovery (24.28%) and total carbohydrate content (42.33%). Vacuum drying emerged as the most effective dehydration method, followed by microwave drying, due to their superior retention of key nutrients and antioxidant properties. The vacuum-dried whole leaf and leaf powder of Moringa were packaged using HDPE (200 gauge), LDPE (200 gauge), and polyethylene-laminated aluminium pouches and stored under ambient and refrigerated (4–6°C) conditions for three months. Biochemical, mineral, microbial, sensory, and antioxidant analyses were conducted at monthly intervals to evaluate storage effects. The results of the third experiment revealed that packaging materials and storage conditions significantly influenced the biochemical, mineral, antioxidant, microbial, and sensory properties of dried Moringa oleifera leaves over a three-month storage period. Leaf powder stored in polythene-laminated aluminium pouches under refrigerated conditions (T12) emerged as the most effective method, maintaining the lowest moisture content (5.95–6.02%), highest retention of total phenols (158.21– 159.63 mg GAE/100g), ascorbic acid (133.28–133.32 mg/100g), and total chlorophyll (357.66–390.53 mg/100g). In contrast, whole leaves stored in LDPE pouches under ambient conditions (T2) resulted in the highest moisture content (7.97–10.21%), significant nutrient degradation, and the lowest overall acceptability (5.72–6.57). Refrigerated storage also minimized microbial load, with T12 recording the lowest microbial count ( aerobic plate count - 0.40–2.00 × 10⁴ cfu/g), while ambient-stored samples (T2) exhibited the highest microbial growth (1.50–10.30 × 10⁴ cfu/g). Sensory evaluation confirmed that leaf powder stored in polythene laminated aluminium pouch under refrigeration (T12) retained superior sensory attributes, achieving the highest overall acceptability score (8.71) by the end of the storage period. Mineral content, including iron, calcium, and potassium, showed a gradual decline over time, with refrigerated storage (T7, T8, T9, T10, T11, T12) preserving higher levels compared to ambient storage. For instance, T7 (whole leaves stored in HDPE under refrigerated conditions) and T10 (leaf powder stored in HDPE under refrigerated conditions) retained the highest iron content (15.26–15.29 mg/100g), while T12 maintained the highest potassium content (0.86–0.92%). Antioxidant activity, measured by IC₅₀ values, also declined over time, with refrigerated samples (T12) exhibiting the lowest IC₅₀ values (4.59–6.03 mg/ml), indicating better retention of antioxidant potential compared to ambient-stored samples (T2) with IC50 value of 7.87–14.88 mg/ml. Overall, refrigerated storage in polythene-laminated aluminium pouches (T12) proved to be the most effective method for preserving the nutritional, sensory, and microbial quality of Moringa leaves, making it the preferred choice for long-term storage. The findings of the study revealed that Moringa leaves can be effectively preserved using microwave blanching, vacuum drying, and refrigerated storage in polythene-laminated aluminium pouches, maintaining their nutritional, sensory, and microbial quality for up to three months. The findings highlight the importance of advanced preservation and packaging techniques in retaining nutrient content and quality. Future research should focus on advanced preservation techniques, ecofriendly packaging, and scaling up production for commercial use. Additionally, exploring value-added products, nutrient bioavailability, and smart packaging technologies can enhance the sustainable utilization of Moringa leaves for global nutrition and food security.