Evaluation of shelf life of freeze-dried avocado cv. Hass (Persea americana Mill.)

Abstract

Objectives: To evaluate the shelf life of freeze-dried (PL) Hass avocado (Persea americana Mill.) slices packed in low density polyethylene zipper bags (LDPE) and bilaminate metalized zipper bags (BLM). Methodology: Two types of LDPE and BLM packaging were used, and the thickness of each avocado sample was evaluated (3, 5, 7 mm), with 3 mm being optimal. The samples were previously frozen (-16, -20, -24 °C) for 24 h to avoid enzymatic browning. Freeze-drying was performed at -57°C, and 5 mtorr, at times of 18, 24 and 30 h, then the shelf life was evaluated. Results: The peroxide index for PL in LDPE packaging was 5.53 ± 0.035 (meqO/Kg) and for BLM packaging was 5.10 ± 0.04 (meqO/Kg). The percentage of fat in LDPE-packaged PL was 19.24 ± 0.01 and for BLM-packaged PL was 19.12 ± 0.012. The pH of PL in LDPE packaging was 6.87 ± 0.042 and in BLM packaging was 6.91 ± 0.031. Likewise, the Aw in PL packaged in LDPE was 0.516 ± 0.002 and in BLM was 0.515 ± 0.003. Microbiological analyses reported absence of molds, yeasts, E. coli and Salmonella sp. The shelf life of PL stored at 25 °C and packaged in LDPE was 56.67 days and for PL packaged in BLM was 60.96 days. Conclusions: The shelf life of PL packaged in BLM presents a better option for storage of avocado cv. Hass..