The assessment of the physico-chemical, microbiological and kinetic parameters of acidulants used in the production of acidified dried sausages made from the meat of blesbok (Damaliscus pygargus phillipsi)

van den Honert, Mathew Paul (2015-12)

Thesis (MSc Food Sc)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: The physico-chemical, microbiological and kinetic parameters of Blesbok (Damaliscus pygargus phillipsi) dry acidified sausage produced by chemical acidification were assessed. Initially, Blesbok meat dry acidified sausage was manufactured using five different concentrations of Glucono-delta-lactone (GdL), notable 0.5, 1.0, 1.5, 2.0 and 3.0%. All of the treatments pHu differed (P<0.05) from one another, although, only 1.5, 2.0 and 3.0% were below 5.0. Water activity aW, mass loss and hardness also differed (P<0.05) where 2.0 and 3.0% had the lowest aW, the highest mass loss and highest hardness values. Microbiologically, only 3.0% was safe to consume although 1.5 and 2.0% would suffice if the spice raw material was not contaminated. The choice of 1.5% was considered the optimal concentration in the dry acidified sausage based on the physico-chemical and microbiological results. Kinetic parameters confirmed that heating at 55°C for 65 min released the acidulant from the encapsulate and fully acidified the dry acidified sausage. A brief comparative study between the probe and sodium iodoacetate method of pH measurement was conducted. Similar regressions were developed however, the simpler probe method had a better fit (R2 = 0.9673) compared to (R2 = 0.8944), resulting in the simpler probe method being chosen for the continuation of the study. Further to this, eight concentrations, one through to eight percent, were produced for each of the three encapsulated acidulants. Upon heating to 55°C for 65 min, the sausage batter was acidified. Measurements for pH enabled linear regressions, E-GdL y = -16.81 x + 6.0214 (R2 = 0.9694); E-Lacic acid y = -13.31x + 5.5864 (R2 = 0.9435); E-Citric acid y = -29.536x + 6.0279 (R2 = 0.9844), to be calculated. Validation of the trend lines ensued using a 4 x 6 block design where masses of encapsulated acidulant were weighed out according to the value calculated from the trend line regression equations based on a final pH of 4.8. The optimal GdL concentration of 1.5% was used as a control. Only the GdL treatment pH at 4.9 ± 0.06 was close to the target pH of 4.8. All other treatments differed (P<0.05) from one another and were lower than the target pH; E-GdL = 3.7 ± 0.02, E-Lactic acid = 4.2 ± 0.04 and E-Citric acid = 3.5 ± 0.08. E-citric acid had an apparent crumbly texture which was confirmed by the Max Force 2 (second compression force) value. All the treatments, although well below the required pH, fell in line with the requirements of dried acidified sausage with mass loss > 30% and moisture loss ca. 30%.

AFRIKAANSE OPSOMMING: Die fisiese, chemiese, mikrobiologiese en kinetiese parameters van Blesbok (Damaliscus pygargus phillipsi) droë versuurde-wors, wat geproduseer is deur ‘n chemiese versuringsmetode, is geëvalueer. Eerstens was Blesbok droë versuurde-wors vervaardig met die gebruik van vyf verskillende konsentrasies van Glukono-delta-laktoon (GdL) naamlik, 0.5, 1.0, 1.5, 2.0 en 3.0%. Al die behandelings het van mekaar verskil op grond van pHu (P<0.05), maar slegs konsentrasies 1.5, 2.0 en 3.0% het ‘n pHu van laer as 5.0 gehad. Op grond van water aktiwiteit (aw), massa verlies en hardheid was daar ook verskille (P<0.05) tussen die behandelings, met 2.0 en 3.0% wat die laagste aw, hoogste massa verlies en hoogste hardheid gehad het. Op mikrobiologiese vlak was slegs 3.0% veilig vir verbruikers, maar 1.5 en 2.0% sal ook voldoende wees indien die roumateriale van die speserye nie gekontamineer is nie. Met hierdie inligting in ag geneem, is 1.5% geïdentifiseer as die optimale konsentrasie om droë versuurde-wors te vervaardig. Kinetiese parameters het bevestig dat verhitting teen 55°C vir 65 min die versuringsmiddel vanuit die kapsule vrystel en die droë versuurde-wors ten volle versuur het. ‘n Vergelykende studie is gedoen om die elektrode en natrium iodoasetaat metodes van pH meting te vergelyk. Soortgelyke regressies was saamgestel, maar die eenvoudiger elektrode metode het ʼn beter passing getoon met R2 = 0.9673 teenoor R2 = 0.8944 van die natrium iodoasetaat metode. Weens die beter passing op die regressielyn asook die eenvoudiger metode, is die elektrode pH metode gekies vir gebruik vir die res van die studie. Verder is agt konsentrasies (vanaf 1 tot 8 persent) gebruik vir elk van die drie versuringskapsules. Tydens die verhitting van 55°C vir 65 min, was die wors mengsel versuur. Die meting van pH het hom na lineêre regressie verleen: E-GdL y = -16.81 x + 6.0214 (R2 = 0.9694); E-melksuur y = -13.31x + 5.5864 (R2 = 0.9435); E-sitroensuur y = -29.536x + 6.0279 (R2 = 0.9844), ter berekening. Die geldigheid van die tendens lyne is getoets deur die gebruik van ‘n 4 x 6 blokontwerp, waar massas van die versuringskapsules geweeg is volgens die waarde wat vanaf die regressie vergelyking se tendens lyn bereken is, met die gebruik van ‘n finale pH van 4.8. Die optimale GdL konsentrasie van 1.5% is gebruik as die kontrole. Tydens hierdie eksperiment was slegs die GdL behandeling se pH van 4.9 ± 0.06 naby die vereiste pH van 4.8. Al die behandelings het van mekaar verskil (P<0.05) en was laer as die vereiste pH; E-GdL = 3.7 ± 0.02, E-melksuur = 4.2 ± 0.04 en E-sitroensuur = 3.5 ± 0.08. E-sitroensuur het ‘n duidelike krummelrige struktuur gehad wat bevestig is deur die Maksimum Krag 2 (tweede kompressie krag) waarde. Al die behandelings (ten spyte van die lae pH) was in lyn met die vereistes van droë versuurde-wors met ‘n massa verlies van > 30% en vog verlies ~ 30%.

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