Calcium ascorbate dips help to maintain fresh-cut apple quality

Fresh-cut ?Braeburn? apple slices were dipped into cold water (4?C for 2 min) or hot water (HWT, 48?C or 55?C for 2 min) followed by dips into 0 or 6% w/v aqueous calcium ascorbate (CaAsc, 2 min, 0 ?C) and stored in air up to 28 d at 4 ?C. Microbial counts, changes in browning and sensory acceptance were determined to indicate changes in quality. Changes in antioxidant levels were measured using free radical scavenging activity (DPPH), reducing activity (FRAP), ascorbic acid content (AA) and polyphenolic content (by HPLC). CaAsc dips had a strong impact reducing the browning through increasing the flesh luminosity and hue angle. 6% CaAsc in fresh-cut apples extended the overall acceptability from less than 7 d to 14 d. Immediately after CaAsc treatment, AA content was 5 fold higher (0.25?1.25 g kg?1) than those not dipped into CaAsc. However, the combination of HWT treatments and CaAsc dips led to seven fold increased levels of AA inside the apple tissue (0.25?1.85 g kg?1) and consequently increased the antioxidant activity. HWT did not increase the AA content when not combined with CaAsc dips. The HWT CaAsc dip extended the overall acceptability to 21 d compared to 14 d for samples not heated but dipped into CaAsc. Shelf life was ultimately limited by sensory quality. At day 28, total plate counts were reduced from 5.3 log cfu/g (untreated slices) to 4.6 log cfu/g in the 6% CaAsc dips and further to 3.9 log cfu/g with the combination of HWT and CaAsc dip. Changes in the content of phenolic compounds with time, HWT and CaAsc dip were generally not significant except for slightly increased quercetin and phloridzin levels and decreased p-coumaric and procyanidins over time. The combination of HWT at 48 ?C for 2 min followed by 6% CaAsc dip would be best for preserving the eating quality of apple slices SourcesHot water treatment in combination with calcium ascorbate dips increases bioactive compounds and helps to maintain fresh-cut apple qualityEncarna Aguayo(a), Cecilia Requejo-Jackman(b), Roger Stanley(c), Allan Woolf(b)a Postharvest and Refrigeration Group. Department of Food Engineering, Technical University of Cartagena. Paseo Alfonso XIII 48, 30203 Cartagena, Murcia, Spainb The New Zealand Institute for Plant & Food Research Ltd, Private Bag 92169, Auckland, New Zealandc Centre for Food Innovation, University of Tasmania, Locked Bag 1370, Launceston, TAS 7250, AustraliaPostharvest Biology and Technology, Volume 110, December 2015, Pages 158?165The picture is by chefclaudia.com