Evaluation of a natural preservative in a boerewors model system

[摘要] English: Boerewors is a South-African fresh sausage, made from beef and pork and flavoured with salt, pepper and various spices, especially coriander. It may contain a maximum of 450 mg/kg SO2 as preservative. Until recently, the use of SO2 has had GRAS (Generally Regarded as Safe) status. Investigations have indicated certain asthmatic individuals were placed at risk by relatively small amounts of sulphites. The increased demand for minimally processed, extended shelf-life foods have renewed interest in exploitation of natural antimicrobials for food preservation uses. The aim of this study was to evaluate the efficacy of Citrox as a natural preservative in Boerewors. Citrox comprises of a range of phyto-alexins derived from the pith and rind of green Bergamont oranges and fruit acids. Seven Boerewors models were made following a typical commercial procedure: the control containing no preservative, current dosage of SO2 in Boerewors (450 mg/kg), two dosages of Citrox on its own at 1% and 2% addition, a reduced amount of SO2 (100 mg/kg) on its own and Citrox in combination with reduced amounts of SO2 (1% Citrox + 100 mg/kg SO2 and 2% Citrox + 100 mg/kg SO2). The models were stored at 4 ºC for 6 days under retail display conditions. The models were evaluated every 48 hours for microbiological growth as expressed by total aerobic plate count (TAPC), coliform count, Staph. aureus count, yeast and mould count. The models were also evaluated every 48 hours for colour changes as expressed by the colour a* value (redness), colour b* value (yellowness) and colour L* value (lightness). The models were evaluated after 6 days, and again after 100 days storage at -18 ºC, for lipid oxidation as expressed by TBARS (thiobarbituric acid reactive substance). The models were also evaluated organoleptically by a sensory panel. It was established that all the treatments had significantly lower counts than the control over the 6 day storage period on TAPC. There was no significant difference in the counts of 450 mg/kg SO2, 2% Citrox, 100 mg/kg SO2 + 1% Citrox and 100 mg/kg SO2 + 2% Citrox. The 450 mg/kg SO2 and 100 mg/kg SO2 + 2% Citrox had significantly lower coliform counts than the control. Against yeasts and moulds, 100 mg/kg SO2 + 2% Citrox had significantly lower counts than the control and 450 mg/kg SO2. Citrox had a negative effect, on its own and in combination with 100 mg/kg SO2 on the colour of the Boerewors. The colour a* values were significantly lower than those for the control and 450 mg/kg SO2. There was very little effect on the colour L* value, most values stayed relatively stable over the 6 days, the 2% Citrox and 100 mg/kg SO2 + 2% Citrox showed the highest values. For all the models, there were a slight decrease in the colour b* value. At the end of the 6 days, all models had similar values. Over the 6-day fresh display period there was no significant difference in the TBARS values for all the models. After 100 days storage at -18 ºC, 450 mg/kg SO2 had significantly lower values than the control and the rest of the models. The control had the same values as the rest of the models, which led to the conclusion that although the Citrox had no anti-oxidant capabilities, it also did not increase lipid oxidation. The sensory panel found that the models containing 2% Citrox had a slight sour flavour (can be explained by the fruit acids in Citrox in combination with the vinegar added to the Boerewors formulation), however the average scores for these models were still found to be 'liked slightly to 'liked moderately.

[发布机构] University of the Free State