Freeze-drying and amber glass: a superior synergy for preserving the vitamin C and bioactive wealth of green chilli powder.

PROBLEM AND AIM: Green chillies are rich in bioactive compounds but suffer significant nutrient loss during conventional drying and storage. This study aimed to systematically evaluate the effects of four drying methods-sun drying (SD), tray drying (TD), microwave-assisted vacuum drying (MaVD), and freeze-drying (FD)-on the physicochemical properties of green chilli powder, and to assess the impact of three packaging materials (low-density polyethylene [LDPE], clear glass, and amber glass) during six months of storage.

REMARKABLE

RESULTS

Freeze-drying (FD) significantly outperformed other methods, retaining the highest levels of capsaicin (73.50 ± 0.22 mg/100 g), total chlorophyll (142.48 ± 0.18 mg/100 g), total phenolics (39.76 ± 0.38 mg GAE/100 g), and vitamin C (113.40 ± 0.28 mg/100 g). Scanning electron microscopy (SEM) revealed that FD preserved a porous, intact microstructure, while other methods caused structural collapse. During storage, amber glass jars provided superior protection against light and oxygen, preserving chlorophyll and vitamin C significantly better than LDPE and clear glass (p < 0.05).

SIGNIFICANCE OF STUDY: This study establishes an integrated "process-package" strategy combining FD with amber glass packaging. This approach effectively bridges the gap between processing and long-term storage, offering a commercially viable method for producing high-quality, shelf-stable green chilli powder with maximized bioactive retention for the nutraceutical and functional food industries.