The effect of sodium reduction on the chemical, microbial and sensory quality of prominent South African processed meat products
Abstract
English: In light of the recent South African regulations limiting the sodium content of processed meat
products, the latest draft of these regulations were used to establish to what extent commercial
processed meat products deviated from these limits and required reformulation, two and a half years
in advance of the first reduction limits coming into effect. Almost 60% of product labels already
included information on sodium content almost three years before the applicable labelling
regulations came into effect. Surveying nationally and regionally available products allowed for the
identification of the five largest product classes. A comparison between labelled and determined Na
content revealed that processors tended to overestimate Na content as a precautionary measure. A
generous tolerance of 20% for underestimating the Na content, as stated in the labelling regulations
draft, showed that only a small number of products would at the time, have exceeded the futuredated
regulatory limits.
Bacon, polony and pork bangers, representing the three most populous classes were used to
evaluate the efficacy of the two-part regulatory limits as intermediate added NaCl levels without
replacers or alterations in processing. Water activity, pH and moisture content were inconsistently
affected with no definite links to deviations in dependent parameters such as microbial stability.
Microbial and oxidative stability and sensory quality results were encouraging. Current processing
techniques and ingredients other than NaCl maintained quality and stability. Changes in bacon and
banger colour were found, although subjective evaluation is needed to grasp the implications.
Polony texture was deemed acceptable, both quantitatively and qualitatively. Total Na levels better
matching the regulatory limits may further limit the minor deviations in quality and stability.
The relative success of using only 1% NaCl (w/w) in the pork bangers prompted the use of various
compounds, either alone or in combination, to address the gaps in functionality of the 1% NaCl
removed from the original formulation. Potassium chloride (1% w/w), K-gluconate (1% w/w), KCl
(0.8% w/w) with YE (1% w/w) and lastly, KCl (0.8% w/w) with K-lactate (0.2% w/w) were
compared to 1% NaCl and 2% NaCl controls. Treatments containing KCl had improved cooking
losses over that of the controls. The use of K-containing compounds increased the K-content in
addition to reducing Na-content. Basic chemical parameters were similar to that of the 2% NaCl
control with only water activity being more similar to that of the 1% NaCl control. These replacers
did not improve lipid oxidative stability and the use of YE actively deteriorated lipid oxidative
stability. Colour was the most affected multi-component parameter and consumers had less favourable hedonic responses towards the use of K-gluconate. Partial replacement with 1% KCl
was the most suitable solution when additional factors such as price-point, similarity to NaCl, and
ease-of-use were taken into account.
Lastly, the efficacy of the reduction and/or partial replacement of NaCl against the growth and
survival of E. coli and S. aureus inoculated into banger batters were monitored. No effects on E.
coli were observed beyond the bacteriostatic effect of sub-optimal temperatures (4 °C and 10°C)
and the anti-microbial effects of the other additives in the formulations. At reduced NaCl levels, S.
aureus was unable to grow and survival rate ultimately decreased. Partial replacement led to limited
growth although survival rates eventually decreased. Survival rates were highest at 1% NaCl, 1%
KCl and 0.2% K-lactate. Sub-optimal temperatures and other anti-microbial effects overrode that of
partial NaCl replacement. Beyond the initial inoculation levels, reduction and/or partial replacement
of NaCl did not increase the food safety risk of these bacterial species.
This research showed that conformation with the regulatory limits warrants a back-to-basics
strategy using multiple approaches that deliver better results when these approaches are linked to
one another. Afrikaans: Na aanleiding van die onlangse Suid-Afrikaanse regulasies wat die natriuminhoud van verwerkte
vleisprodukte beperk, is die mees onlangse weergawe van hierdie regulasies ingespan om vas te stel
tot watter mate kommersiële verwerkte vleisprodukte afwyk van hierdie perke en of herformulering
benodig word, twee en „n half jaar voordat die eerste verlagingsperke in werking tree. Amper drie
jaar voordat die toepaslike etiketregulasies in werking sou tree, is daar bevind dat byna 60% van
produketikette reeds natriuminhoud beskryf het. „n Opname van nasionaal en plaaslik beskikbare
produkte het dit moontlik gemaak om die vyf grootste produkklasse te identifiseer. „n
Daaropvolgende vergelyking tussen etiket en ontleedte natriuminhoud het uitgewys dat
vleisverwerkers geneig het om die natriuminhoud as „n voorsorgmatreël te oorskat. „n Ruim speling
van 20% vir die onderskatting van die natriuminhoud, soos beskryf in die etiketregulasies, het
aangedui dat slegs „n klein aantal produkte op daardie stadium die toekomstige regulasieperke sou
oorskry.
Spek, polonie en varkwors as verteenwoordigers van die drie grootste klasse is as modelle gebruik
om die doeltreffendheid van die tweeledige regulasieperke as intermediêre toegevoegde soutvlakke
te evalueer sonder vervangers of veranderinge in verwerking. Wateraktiwiteit, pH en voginhoud is
somtyds beïnvloed sonder enige besliste skakels tot afwykings in afhanklike maatstawwe soos
mikrobiese stabiliteit. Resultate van mikrobiese en oksidatiewe stabiliteit sowel as sensoriese
kwaliteit was bemoedigend. Huidige verwerkingstegnieke en bestanddele anders as NaCl het
kwaliteit en stabiliteit gehandhaaf. Veranderinge in spek- en varkworskleur is gevind, alhoewel
subjektiewe evaluering nodig is om die implikasies te begryp. Polonietekstuur is kwantitatief en
kwalitatief as aanvaarbaar beskou. Totale Na-vlakke wat die regulasieperke beter ewenaar mag die
klein afwykings in kwaliteit en stabiliteit verder beperk.
Die relatiewe sukses van die gebruik van slegs 1% NaCl (g/g) in die varkwors het aanleiding gegee
tot die gebruik van verskeie ander verbindings, beide alleen of in kombinasies, om die gapings in
funksie van die verlaagde 1% NaCl aan te spreek. Kaliumchloried (1% g/g), kaliumglukonaat (1%
g/g), KCl (0.8% g/g) met gisesktrak (1% g/g) en laastens, KCl (0.8% g/g) met kaliumlaktaat is
vergelyk met 1% NaCl (g/g) en 2% NaCl (g/g) kontroles. Behandelings wat KCl bevat het, het
kookverliese verbeter teenoor die van die kontroles. Die gebruik van K-bevattende verbindings het
die K-inhoud verhoog benewens die verlaging in Na-inhoud. Basiese chemiese maatstawwe was
soortgelyk as die van die 2% NaCl kontrole, met slegs die wateraktiwiteit wat meer soortgelyk was
as die van die 1% NaCl kontrole. Hierdie vervangers het nie die lipiedstabiliteit verbeter nie, terwyl
die gebruik van gisekstrak dit aftief benadeel het. Kleur, as „n multi-komponent kwaliteit maatstaf, was die meeste beïnvloed en verbruikers het minder gunstige hedonistiese reaksies gehad teenoor
die gebruik van K-glukonaat. Gedeeltelike vervanging met 1% KCl was die mees geskikte
oplossing wanneer verdere faktore soos pryspunt, ooreenkoms met NaCl, en gemak van gebruik in
ag geneem is.
Laastens is die doeltreffendheid van die verlaging en/of gedeeltelike vervanging van NaCl teen die
groei en oorleweing van E. coli en S. aureus wat in varkworsmengsels geïnokuleer is, gemonitor.
Op E. coli is geen effekte gevind buite die bakteriostatiese effek van die sub-optimale temperature
(4 °C en 10 °C) sowel as die anti-mikrobiese effekte van ander bymiddels in die formulasies nie.
Teen verlaagde NaCl vlakke, was S. aureus nie in staat tot groei nie en die oorlewingsyfers het
uiteindelik gedaal. Gedeeltelike vervanging het gelei tot beperkte groei, maar oorlewingsyfers het
uiteindelik gedaal. Oorlewingsyfers was die hoogste by 1% NaCl, 1% KCl en 0.2% K-laktaat. Suboptimale
temperature en ander anti-mikrobiese effekte het die van gedeeltelike NaCl vervanging
oorheers. Buiten die aanvanklike inentingsvlakke het verlaging en/of gedeeltelike vervanging van
NaCl nie die voedselveiligsrisiko van hierdie bakteriese spesies verhoog nie.
Hierdie navorsing het aangetoon dat voldoening aan die regulasieperke „n strategie benodig wat
terugneig na die basiese beginsels en dat gebruik gemaak moet word van verskeie benaderings wat
beter resultate lewer wanneer hierdie benaderings met mekaar verbind word.