Vacuum assisted iron fortification of fresh-cut French beans: process optimization and quality evaluation

The present study was carried out to enhance the iron content of the fresh-cut French beans through vacuum impregnation (VI). For fortification, five iron salts, namely, ammonium ferrous sulphate, ferrous sulphate, ferric pyrophosphate, anhydrous ferric chloride and ferric ammonium citrate were tested as fortificant. Fresh-cut green French beans were dipped in variable concentrations (0.025%, 0.05% and 0.1%) of the iron salts for imbibitions at different time periods (5, 10 and 15 min) under atmospheric pressure. On basis of least colour change and maximum iron absorption, ammonium ferrous sulphate at 0.025% was selected for further study. For VI, different levels of vacuum pressure (50, 75 and 100 mmHg), vacuum time (5, 10 and 15 min) and ascorbic acid (0, 0.5 and 1%) were evaluated for iron impregnation through Box-Behnken design. Maximum iron infusion in fresh-cut beans was achieved at 50 mmHg vacuum pressure, 6 min vacuum time and 0% ascorbic acid. At optimized condition, iron content of the bean increased by 64.05%. The infused beans were stable for a week at 6 ± 1 °C without any discolouration and were microbiologically safe for consumption. Overall, the present study demonstrated that VI has the potential to develop iron fortified fresh-cut ready-to-use French beans.