Utjecaj dodatka prehrambenog kvasca na fizikalno-kemijska i senzorska svojstva polutrajnih kobasica sa smanjenim udjelom soli

professional thesis

• Title (english): The impact of yeast extract addition on the physicochemical and sensory properties of reduced-salt cooked sausages
• Author: Ivana Džepina
• Mentor: Ivica Kos (mentor)
• Committee member: Danijel Karolyi (predsjednik povjerenstva)
• Committee member: Ivica Kos (član povjerenstva)
• Committee member: Jelka Pleadin (član povjerenstva)
• Granter: University of Zagreb; Faculty of Agriculture; (Animal Science and Technology); Zagreb
• Defense date and country: 2025-01-24, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Agronomy

Abstract

Cilj ovoga istraživanja bio je utvrditi utjecaj dodatka 1 % ekstrakta kvasca na fizikalno-kemijska
i senzorska svojstva polutrajnih kobasica sa smanjenim udjelom soli za 15, 25 i 35 %. Za
potrebe istraživanja pripremljena su četiri tretmana kobasica u dvostrukom ponavljanju.
Pokusni tretmani su imali istu osnovnu recepturu kao i kontrolni (KONT) pri čemu je smanjivan
dodatak soli za 15 (RED-15), 25 (RED-25) i 35 % (RED-35), uz povećanje dodatka prehrambenog
kvasca za 1 %. Kobasice su nakon... More pripreme nadjeva i punjenja toplinski obrađene, ohlađene
te čuvane u hladnjaku do analiza. Provedena su mjerenja aktiviteta vode i boje,
instrumentalna analiza teksturnih svojstava, određen je nutritivni sastav te je provedena
senzorska analiza primjenom modificirane kvantitativne deskriptivne analize. Statistička
obrada podataka provedena je u SAS Studio softveru uz Tukey post-hoc test pri razini
značajnosti P=0,05. Istraživanjem je utvrđeno da se aktivitet vode povećavao sa smanjenjem
dodatka soli, s najvećim vrijednostima kod uzorka RED-35. Uzorci s manjim udjelom soli postali
su svjetliji (veća L* vrijednost), s izraženijim žutim tonom (veća b* vrijednost), dok je osnovna
crvena komponenta boje (a*) ostala ujednačena. Kemijski sastav polutrajnih kobasica bio je
ujednačen u sadržaju vode, masti i bjelančevina, dok se sadržaj pepela i soli očekivano
smanjivao, a dodatkom prehrambenog kvasca povećan je sadržaj glutaminske kiseline.
Teksturna analiza uzoraka pokazala je povećanu mekoću i sočnost kod pokusnih tretmana,
osobito kod RED-35, dok su uzorci s manjim smanjenjem soli (RED-15 i RED-25) zadržali bolju
konzistenciju uslijed dodatka kvasca. Senzorski određen intenzitet ružičaste boje smanjivao se
smanjenjem dodatka soli, što ukazuje na razliku između subjektivne i objektivne percepcije
boje. Pored toga, utvrđena je manja slanost i manje skladna aroma kod uzoraka s većim
smanjenjem soli, pri čemu je tekstura kobasica postala mekša i manje povezana. Primijenjena
analiza glavnih komponenti jasno je razlikovala uzorke, smještajući kontrolni uzorak u
područje visokog sadržaja soli i bolje povezanosti te istaknutog slanog okusa, dok su uzorci s
nižim udjelom soli imali drugačije senzorske profile s izraženijom aromom kvasca, mekoćom i
sočnošću, osobito RED-35. Istraživanjem je ustanovljeno da smanjenje soli doprinosi
promjenama fizikalnih, kemijskih, teksturnih i senzorskih svojstava, no dodatak prehrambenog
kvasca pokazuje potencijal za kompenzaciju manjka soli u cilju zadržavanja željenih
karakteristika okusa i teksture polutrajnih kobasica. Less

Abstract (english)

The aim of this study was to determine the impact of adding 1% yeast extract on the
physicochemical and sensory properties of heat-treated sausages with salt reductions of 15%,
25%, and 35%. Four sausage treatments were prepared in duplicate for the study. The
experimental treatments followed the same base recipe as the control (KONT), with salt levels
reduced by 15% (RED-15), 25% (RED-25), and 35% (RED-35), while increasing the yeast extract
addition by 1%. After mixing and stuffing, the... More sausages were thermally processed, cooled, and
stored in refrigeration until analysis. Measurements of water activity and colour were
conducted, along with instrumental texture analysis, determination of nutritional
composition, and sensory analysis using a modified quantitative descriptive approach. Data
analysis was performed using SAS Studio software with Tukey’s post-hoc test at a significance
level of P=0.05. The study revealed that water activity increased as salt levels decreased, with
the highest values observed in the RED-35 sample. Samples with reduced salt became lighter
(higher L* value) and showed a more intense yellow hue (higher b* value), while the primary
red component of colour (a*) remained consistent. The chemical composition of the heattreated
sausages was consistent in terms of water, fat, and protein content, although ash and
salt content decreased as expected, while the yeast extract addition increased glutamic acid
content. Texture analysis indicated increased softness and juiciness in the experimental
treatments, particularly in RED-35, while samples with moderate salt reductions (RED-15 and
RED-25) maintained better consistency due to addition of yeast extract. Sensory evaluation
showed a decline in the intensity of pink colour with reduced salt levels, highlighting a
difference between subjective and objective colour perception. Additionally, reduced salt
samples displayed lower saltiness and less harmonious aroma, with a softer and less cohesive
texture. Principal component analysis (PCA) clearly distinguished the samples, placing the
control treatment in an area with high salt content, better cohesion, and pronounced salty
taste, while lower-salt samples exhibited different sensory profiles, with more prominent
yeast aroma, softness, and juiciness, particularly in RED-35. The study concluded that salt
reduction contributes to changes in physical, chemical, textural, and sensory properties, but
the addition of yeast extract demonstrates potential to compensate for reduced salt,
maintaining the desired flavour and texture characteristics of cooked sausages. Less

• Keywords: polutrajne kobasice; smanjenje soli; prehrambeni kvasac; glutaminati; senzorska analiza; nutritivni sastav; tekstura
• Keywords (english): heat-treated sausages; salt reduction; nutritional yeast; glutamates; sensory analysis; nutritional composition; texture
• Language: croatian
• URN:NBN: urn:nbn:hr:204:412722
• Study programme: Title: Animal Sciences; Study programme type: university; Study level: postgraduate specialist; Academic / professional title: sveučilišni/a specijalist/ica stočarstva (sveučilišni/a specijalist/ica stočarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2025-01-31 09:43:33