Evaluation of a natural preservative in a boerewors model system

Loading...
Thumbnail Image
Date
2010-05
Authors
Van Schalkwyk, Charles Petrus Benjamin
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State
Abstract
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”.
Afrikaans: Boerewors is ‘n Suid-Afrikaanse wors wat gemaak word van bees- en varkvleis en dit word gegeur met sout, peper en verskeie speserye, veral koljander. Dit mag ‘n maksimum van 450 mg/kg SO2 bevat. Tot onlangs het die gebruik van SO2 GRAS (Generally Regarded as Safe – Algemeen Aanvaar as Veilig) status geniet. Ondersoeke het bevind dat sekere asmatiese individue op risiko geplaas word deur relatiewe klein hoeveelhede sulfiete. Die onlangse vraag na minimaal geprosesseerde voedsels met verlengde rakleeftyd het hernude belangstelling in die gebruik van natuurlike antimikrobiese middels vir voedselpreservering laat ontstaan. Die doel van die studie was om die doeltreffendheid van Citrox as ‘n natuurlike preserveermiddel in Boerewors te ondersoek. Citrox bestaan uit ‘n reeks fito-aleksiene, verkry uit die pit en skil van groen Bergamont lemoene, en vrugte sure. Sewe Boerewors modelle is gemaak deur die tipiese kommersiële metode te gebruik: die kontrole met geen preserveermiddel, huidige toediening van SO2 in Boerewors (450 mg/kg), twee toedienings van Citrox teen 1% en 2% op sy eie, ‘n verminderde hoeveelheid van SO2 (100 mg/kg) op sy eie en Citrox in kombinasie met verminderde hoeveelhede SO2 (1% Citrox + 100 mg/kg SO2 en 2% Citrox + 100 mg/kg SO2). Die modelle is gehou by 4 ºC vir 6 dae onder kleinhandel-uitstal kondisies. Die modelle is elke 48 uur geëvalueer vir mikrobiese groei soos uitgedruk in totale aerobiese plaat tellings (TAPT), koliforme tellings, Staph. aureus tellings, gis en skimmel tellings. Die modelle was ook elke 48 uur geëvalueer vir kleur veranderinge soos uitgedruk deur die kleur a* (rooiheid), kleur b* (geelheid) en kleur L* (ligtheid) waarde. Die modelle is na 6 dae, en weer na 100 dae geberg by -18 ºC, geëvalueer vir lipied oksidasie soos uitgedruk deur TBSRS (tiobarbitiensuur reaktiewe stowwe). Die modelle is ook organolepties geëvalueer deur ‘n sensoriese paneel. Daar is gevind dat al die behandelings betekenisvol laer tellings na die 6 dae opbergings periode gehad het as die kontrole vir TAPT. Daar was geen betekenisvolle verskil in die tellings vir 450 mg/kg SO2, 2% Citrox, 100 mg/kg SO2 + 1% Citrox en 100 mg/kg SO2 + 2% Citrox nie. Die 450 mg/kg SO2 en 100 mg/kg SO2 + 2% Citrox se koliforme tellings was betekenisvol laer as die kontrole s’n. Die 100 mg/kg SO2 + 2% Citrox het betekenisvol laer tellings vir giste en skimmels gehad as die kontrole en 450 mg/kg SO2. Citrox, op sy eie, en in kombinasie met 100 mg/kg SO2, het ‘n negatiewe effek op die kleur van die Boerewors gehad. Die kleur a* waardes was betekenisvol laer as die van die kontrole en 450 mg/kg SO2. Daar was baie min effek op die kleur L* waarde, meeste van die waardes het stabiel gebly oor die 6 dae periode, die 2% Citrox en 100 mg/kg SO2 + 2% Citrox het die hoogste waardes gehad. Vir al die modelle was daar ‘n effense afname in die kleur b* waarde. Aan die einde van die 6 dae het al die modelle soortgelyke waardes gehad. Oor die 6 dae vars-vertoon periode was daar geen betekenisvolle verskil in die TBSRS waardes vir al die modelle nie. Na 100 dae opberging by -18 ºC, het 450 mg/kg SO2 betekenisvol laer waardes gehad as die kontrole en die res van die modelle. Die kontrole het dieselfde waarde gehad as die res van die modelle, wat gelei het tot die gevolgtrekking dat alhoewel Citrox nie antioksidant kapasiteit het nie, dit ook nie lipied oksidasie verhoog het nie. Die proepaneel het bevind dat die modelle wat 2% Citrox bevat het ‘n effense suur smaak het (kan verklaar word deur die vrugtesure in Citrox in kombinasie met die asyn wat bygevoeg is in die Boerewors formulasie), hoewel die gemiddelde tellings vir die modelle steeds as “hou effens van” tot “hou redelik van” gevind is.
Description
Keywords
Dissertation (M.Sc.Agric. (Microbial, Biochemical and Food Biotechnology))--University of the Free State, 2010, Meat -- Preservation -- South Africa, Sulphur dioxide, Boerewors, Natural preservative, Citrox, Fresh sausage
Citation