Enhancing Conventional Freezing: Assessing Pretreatments for Optimal Preservation of Selected Vegetables

Vegetables are highly perishable, and their quality during storage depends on effective preservation techniques. This study explored enhancing conventional freezing in eight vegetables (bitter gourd, tender jackfruit, green chili, carrot, pumpkin, jackfruit, jackfruit seeds, and beans) through two blanching methods: steam blanching (SB) and hot water blanching (HB). The blanched vegetables were packed and stored at -18°C for four months.
Post-storage, the vegetables were analyzed for physicochemical, sensory, and microbiological properties. Physicochemical parameters included drip loss, pH, ascorbic acid content, and firmness. SB resulted in lower drip losses (0.5-5%) compared to HB, except in carrots and bitter gourd, which showed higher drip losses (14-15%) with HB. pH remained stable in tender jackfruit and green chili but varied in other vegetables. Firmness declined significantly in most vegetables, with pumpkin and jackfruit showing the least decrease (36.86%), while SB carrots experienced higher softness. Vitamin C content decreased across vegetables, except in tender jack, carrot, and jackfruit seeds, which retained their levels. Microbiological analysis confirmed safety, with no significant growth in total plate count, yeast/mold, or coliforms. Sensory evaluation favored HB-treated frozen vegetables over SB-treated and fresh samples. Freezing also reduced cooking time, enhancing preparation convenience. This study highlights the potential of optimized blanching and freezing techniques to preserve vegetable quality during frozen storage.