Oxidative stability of chicken meat at different oxygen concentrations in the packaging unit

Namen magistrske naloge je bil med devetdnevnim skladiščenjem ohraniti kakovost in preprečiti oksidacijo barvila, lipidov in proteinov v veliki prsni mišici piščancev s pakiranjem v modificirano atmosfero. V ta namen smo preizkusili štiri različne mešanice plinov, kisika, ogljikovega dioksida in dušika: A (0 % O2, 20 % CO2, 80 % N2), B (20 % O2, 20 % CO2, 60 % N2), C (40 % O2, 20 % CO2, 40 % N2) in D (70 % O2, 20 % CO2, 10 % N2). Po 9-ih dneh skladiščenja pri 2 ␃ ± 1 ␃ smo na presnih vzorcih prsi izmerili vrednost pH, instrumentalno izmerili in senzorično ocenili barvo, določili osnovno kemijsko sestavo, število tiobarbiturne kisline (TBK) in vsebnost proteinskih karbonilov. Po toplotni obdelavi (82 ␃, 1 ura, sous vide) pa smo ocenili še preostale senzorične lastnosti vonja in arome ter instrumentalno izmerili teksturo (strižna sila). Sestava plinske mešanice je vplivala na vse parametre oksidacije mesa: (i) barvo: barvni vrednosti L* in b* sta bili največji pri vseh atmosferah s kisikom (B, C in D), vrednost a* pa pri atmosferah A, C in D, (ii) lipidov: število TBK se je značilno povečalo pri atmosferi D po 7. dnevu skladiščenja (vendar še vedno pod mejo senzorične zaznave žarkosti), (iii) proteinov: vsebnost proteinskih karbonilov je bila največja v atmosferah z največ kisika (C in D) ter (iv) senzorične lastnosti: povečana oksidiranost barve in intenzivnost tujih arom v atmosferah s kisikom (B, C in D) ter vonjev in arom po starem v atmosferi brez kisika (A). Najprimernejši način za pakiranje piščančjih prsi je uporaba modificirane atmosfere brez kisika, saj so bile oksidacija lipidov, proteinov in oksidiranost barve med skladiščenjem najmanjše.The aim of this thesis was to preserve the quality and prevent the oxidation of pigments, lipids and proteins in large chicken breast muscle during nine days of storage under modified atmosphere. For this purpose, four different gas mixtures of nitrogen, carbon dioxide and oxygen were used: A (0% O2, 20% CO2, 80% N2), B (20% O2, 20% CO2, 60% N2), C (40% O2, 20% CO2, 40% N2), and D (70% O2, 20% CO2, 10% N2). After 9 days of storage at 2 ␃ ± 1 ␃ we measured pH value, instrumentally and sensory evaluated colour, determined the basic chemical composition, thiobarbituric acid reactive substances (TBARs), and protein carbonyl content of raw chicken breast. After thermal treatment (82 ␃, 1 hour, sous vide) of the chicken breast, sensory characteristics of smell and aroma were evaluated, we also instrumentally measured the texture (share force). The composition of the gas mixture affected all oxidation parameters: (i) colour: the colour values L* and b* were highest in all atmospheres with oxygen (B, C and D), and the value of a* in atmospheres A, C and D, (ii) lipids: the TBARs increased significantly in atmosphere D after seventh day of storage (but still below threshold for sensory sensitivity to rancidity), (iii) proteins: protein carbonyl content was the highest in oxygen-rich atmospheres (C and D) and (iv) sensory properties: increased colour oxidation and intensity of foreign aromas in oxygen atmospheres (B, C and D), increased smell and aromas of stale in oxygen-free atmosphere (A). The most suitable way of packaging chicken breasts is using modified atmosphere without O2, because the oxidation of pigments, lipids and proteins during storage was the lowest