Ascorbic acid losses in vegetables associated with cook-chill food preparation

Abstract

Objective. To assess ascorbic acid (AA) losses in four vegetables (broccoli, peas, cauliflower and cabbage) at each production stage in a cook-chill food service system. Setting. A long-stay psychiatric hospital in Cape Town. Design. Cross-sectional analytical study. On two repeat occasions, three samples of each vegetable were taken at the following stages: (i) delivery (day 1); (ii) after preparation (day 2); (iii) after cooking (day 5); (iv) after blastchilling (day 5); and (v) in the holdroom and after regeneration over a 4-day period (days 6 -9). AA content of each sample was assessed in duplicate using the 2,6 dichloroindophenol method of titration. Statistical analyses. Differences between the AA concentration of each vegetable at baseline (delivery) and at subsequent stages in food production were assessed using analysis of variance (ANOVA) methods. Results. The most dramatic AA losses occurred during the cooking stage (mean loss 58%, standard deviation (SD) 19.5%, range 33 -81%), with broccoli showing the greatest mean loss of 81% (SD 2.9%). During storage in the holdroom from day 6 to day 9, the average daily loss was 4.3% (SD 4.2%). Further average losses of 6.1% (SD 3.6%) were incurred after regeneration on each day. Mean AA losses on day 6 of production and after regeneration (the earliest time a patient would receive the vegetable) were 87% (SD 5.6%). On day 9 after regeneration (the latest time it could be received by a patient) mean losses were 89% (SD 10.5%). Conclusion. Use of a cook-chill food service system needs to be carefully controlled in order to minimise AA losses. In particular, prolonged cooking times should be avoided and vegetables should be immersed into rapidly boiling rather than cold water. A reduction of the number of days in the chilled storage holdroom would not substantially reduce overall AA losses. Design. Cross-sectional analytical study. On two repeat occasions, three samples of each vegetable were taken at the following stages: (i) delivery (day 1); (ii) after preparation (day 2); (iii) after cooking (day 5); (iv) after blastchilling (day 5); and (v) in the holdroom and after regeneration over a 4-day period (days 6 -9). AA content of each sample was assessed in duplicate using the 2,6-dichloroindophenol method of titration. Statistical analyses.Differences between the AA concentration of each vegetable at baseline (delivery) and at subsequent stages in food production were assessed using analysis of variance (ANOVA) methods.Results. The most dramatic AA losses occurred during the cooking stage (mean loss 58%, standard deviation (SD)19.5%, range 33 -81%), with broccoli showing the greatest mean loss of 81% (SD 2.9%). During storage in the holdroom from day 6 to day 9, the average daily loss was 4.3% (SD 4.2%). Further average losses of 6.1% (SD 3.6%) were incurred after regeneration on each day. Mean AA losses on day 6 of production and after regeneration (the earliest time a patient would receive the vegetable) were 87% (SD 5.6%). On day 9 after regeneration (t...

Food cooking methods contribute to the reduced vitamin C content of foods prepared in hospitals and care facilities: a systematic review

“…Traditionally, food and meals served in hospitals or care facilities were prepared in in‐house kitchens and held in heated units until being served to residents (Charlton et al ., ). However, the evolution of food service has seen the cook‐chill model rise in popularity and involves foods being cooked, then chilled for up to 5 days prior to serving and reheated for provision to patients (Williams, ; Charlton et al ., ).…”

“…Traditionally, food and meals served in hospitals or care facilities were prepared in in‐house kitchens and held in heated units until being served to residents (Charlton et al ., ). However, the evolution of food service has seen the cook‐chill model rise in popularity and involves foods being cooked, then chilled for up to 5 days prior to serving and reheated for provision to patients (Williams, ; Charlton et al ., ). Whilst the cook‐serve method is the most popular system used in the United States, the cook‐chill or cook‐freeze system has become the predominant system used for food production within Australian hospitals (Edwards & Hartwell, ).…”

“…Numerous reports have documented that long‐stay hospital patients or elderly institutionalised individuals have low concentrations of blood ascorbic acid (Jones et al ., ; Charlton et al ., ). Consequences of low blood vitamin C levels have been linked to negative health outcomes within this population group including progressive weakness, fatigue, delayed wound healing and depression (Charlton et al ., ).…”

“…Numerous reports have documented that long‐stay hospital patients or elderly institutionalised individuals have low concentrations of blood ascorbic acid (Jones et al ., ; Charlton et al ., ). Consequences of low blood vitamin C levels have been linked to negative health outcomes within this population group including progressive weakness, fatigue, delayed wound healing and depression (Charlton et al ., ). Low vitamin C levels could be attributed to reduced oral intake of the vitamin, reduced absorption from the gastro‐intestinal tract and a low variety in foods served (Williams, ; Charlton et al ., ).…”

“…Vitamin C is the most heat labile vitamin making it susceptible to degradation when exposed to heating, whilst up to 10% of vitamin C losses can also be anticipated during chilling processes (Charlton et al ., ; Konas et al ., ). Vitamin C losses in heating of food have been attributed to oxidative destruction, and to leaching of the vitamin into cooking water (Charlton et al ., ). Substantial losses may also occur from the reheating (in the case of cook chill systems); these losses are greater when a bulk volume is reheating, as compared with individually heated food (Williams, ).…”