Effect of batch infrared extraction pasteurizer (BIREP)‐based processing on the quality preservation of dried lime juice

Abstract

Infrared irradiation is an alternative method for the thermal processing of foods. Lime is one of the citrus fruits and considered beneficial for human health. Dried lime juice is common in the Middle Eastern region and alternatives are desired to the conventional resistance heating method for the elimination of undesirable microorganisms. A batch infrared extraction pasteurizer (BIREP) was developed to test both infrared and conventional heating methods. Dried lime juice was treated in the BIREP using combinations of temperature (60, 75, and 90°C) and power output (350, 525, and 700 W) from infrared bulbs using a central composite design. Samples were subsequently analyzed for dependent variables of ascorbic acid content, total phenolic content, antioxidant activity, pectin methylesterase, hydroxymethyl, total plate counts, lightness, redness, and yellowness. Each combination of temperature and power was also quantified for specific infrared energy consumption, energy efficiency, and productivity. BIREP temperature and power settings were optimized for all dependent variables. The resulting optimized settings were used to process another set of dried lime juice samples. These samples were compared to control (untreated) and conventional heating samples. Sensory (appearance, aroma, taste, and overall acceptability) evaluation was conducted by a panel of humans. Infrared processing was superior to conventional processing and equivalent to control samples in all four sensory tests. The results indicated strong potential for infrared processing as a superior alternative to conventional heating for the preservation of dried lime juice. Practical applications Infrared heating offers a safe alternative to conventional resistance heating that equals or improves the consumer-desired characteristics compared to fresh dried lime juice and provides a marked improvement over conventional heating. This may allow infrared processed juice to warrant a price premium over conventional thermal processing. Since dried lime producers typically thermally process their juice using the batch method, they can switch to infrared heating to improve the quality of their processed juice and promote the resulting benefits. Cost-benefit studies would be appropriate for dried lime juice processers to evaluate the conversion of thermal processing to infrared heating to take advantage of the superior product.