Title: CITRIC ACID CAN CONTROL MICROBIAL GROWTH IN ENZYME PEELED ORANGE WITHOUT AFFECTING EATING QUALITY Authors
Submitted to: International Fresh Cut Produce Association Annual Conference
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2006
Publication Date: N/A
Technical Abstract: Oranges can be satisfactorily processed for fresh slices using a process of enzyme infiltration under vacuum. Scored ‘Valencia’ and ‘Hamlin’ oranges were placed under 90 kPa vacuum in a 0 ppm (water-infused) or 1000 ppm enzyme solution (Ultrazyme) at 30 °C for 2 min, followed by 30 min incubation in air. Peel was then removed, peeled fruit were washed, blotted dry, cut, and slices were then dipped in water, 1% citric acid (CA), or 0.5% peroxyacetic acid (PAA) (‘Valencia’ only) for 2 min. Drained slices were then placed in 16 oz deli containers and stored at 5 °C for up to 21 d. One additional treatment involved vacuum infiltrating scored oranges in 1% CA, without further dipping of cut slices. All ‘Valencia’ slices had <1.0 log10(cfu/g) after 7 d storage. The PAA dips delayed microbial growth from water-dipped slices for water-infused fruit up to 14 days, while the CA dip delayed microbial growth for 21 days. At 21 days, neither the post-cut dip in CA nor PAA lowered bacterial count of slices from enzyme-infused fruit. For ‘Hamlin’, CA controlled bacterial growth on slices from water-infused oranges, except at 14 days. CA also reduced bacterial contamination on slices from enzyme-infused fruit initially, but enzyme-infused oranges all had low counts after 7 days. CA–treated slices (post enzyme treatment or by infusion) had higher titratable acidity initially (‘Hamlin’) and after 14 days (‘Valencia’). Slices from CA- and enzyme-infused fruit, the latter with slices dipped in CA, had higher total soluble solids (TSS) content; slices from water infused fruit, then dipped in CA, had the same TSS than those dipped in water. Overall flavor was not affected by the CA treatment as evaluated by a taste panel. Enzyme treatments reduced firmness, which was preferred for ‘Valencia’ by the sensory panel. Citric acid is useful for reducing microbial counts of enzyme-peeled oranges, both as an infusion bath or as a post-cutting dip with no adverse flavor effects.