The vitamin C status of freeze-chilled mashed potato G.A. Redmond a, * , A.M. Decazes a , T.R. Gormley a , F. Butler b a Teagasc, The National Food Centre, Dunsinea Castleknock, Dublin 15, Ireland b Department of Agricultural and Food Engineering, UCD, Earlsfort Tce., Dublin 2, Ireland Received 21 October 2001 Abstract Both freeze-chilling and chilling reduce the vitamin C content of mashed potato in comparison with freezing. The current trial investigated the potential of encapsulated vitamin C (EVC) for boosting the vitamin C content of mashed potato. Preliminary trials withEVCinaqueoussolutionindicatedthatthevitaminCwasnotreleasedfromthecapsulesuntilthetemperaturereached 67 °C, i.e.themeltingpointoftheencapsulatingfat.Samplesofcooledmashedpotato(cultivarRooster)weresupplementedwithEVCand were subjected to four process treatments, i.e. fresh, chilling, freeze-chilling and freezing. Parallel tests were conducted with ordinary vitamin C (OVC) and with no vitamin C (NVC) (i.e. control samples). The vitamin C content of the reheated samples with added EVC from the four process treatments was 24.4 mg/100 g (fresh), 16.4 (chill), 14.3 (freeze-chill), 22.4 (freeze). Corresponding contents using OVC were 25.3, 2.4, 2.8, and 19.1 mg/100 g and NVC were 2.0, 1.5, 0.5 and 0.8 mg/100 g respectively. These data show that EVC has potential for boosting the vitamin C content of both freeze-chilled and chilled mashed potato. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Encapsulated vitamin C; Freeze-chilling; Mashed potato 1. Introduction Freeze-chill technology involves freezing and frozen storage (30 °C or colder) followed by thawing and chilled retail display (4 °C) (O’Leary, Gormley, Butler, & Shilton, 2000). This allows ‘chilled’ foods to reach more distant markets, facilitates bulk production, and reducesthelevelofproductrecalls.VitaminCisahighly labile nutrient and a number of authors have reported losses of this vitamin in cooked, and then chilled vege- tables (Bognar, 1990; Williams, Ross, & Miller, 1995) and in freeze-chilled mashed potato (Decazes, Red- mond, Gormley, & Butler, 2001; O’Leary et al., 2000). This is most likely due to oxidation during the chill phase of the process. To overcome this, the addition of encapsulated vitamin C (EVC) to freeze-chilled mashed potato was investigated in the current tests. Encapsula- tion is a process by which liquid droplets or solid par- ticles are packed in continuous shells. These shells or microcapsules give maximum protection from deterio- ration during processing. 2. Materials and methods Trial 1 investigated the rate of release of vitamin C from commercial samples of vitamin C encapsulated with partially hydrogenated vegetable oil (Cap-Shure, Balchem Corporation, New York, USA). This had a vitamin C content of 68–72% (w/w). The EVC was ad- ded to distilled water and heated on a hot plate with continuous stirring. The amount of vitamin C in solu- tion was recorded at 5 °C intervals from 20–90 °C. Parallel tests were conducted with ordinary vitamin C (OVC). Trial 2 investigated the effect of freeze-chilling on the stability of EVC in mashed potato. Cooled mashed potato sample sets (20 g/pot; cultivar Rooster) were prepared containing (a) OVC (33 mg/100 g), (b) EVC (50 mg/100 g), and (c) no vitamin C (NVC), i.e. control sample. The vitamin C content was tested by the 2,6- dichloroindophenol titrimetric method (Anonymous, 1997). Journal of Food Engineering 56 (2003) 219–221 www.elsevier.com/locate/jfoodeng * Correspondingauthor.Tel.:+353-1-8059500;fax:+353-1-8059550. E-mail address: gredmond@nfc.teagasc.ie (G.A. Redmond). 0260-8774/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII:S0260-8774(02)00255-8