| Summary: | A perfect combination of temperature and time is important in sous-vide preparation
because it could provide tenderness, good water-holding capacity, color properties, and better
palatability. The selection of appropriate temperature and time for cooking of various muscles
are the key factors to manipulate the eating quality as described. The challenges are to cope
with the mild cooking regimes and to balance both the physicochemical characteristics and the
taste attributes. In this study, goat muscles gluteus medius (GM) and biceps femoris (BF), and
beef from Hanwoo semitendinosus (ST) were used for sous-vide preparation. Various
temperatures and times were subjected in order to find the right combination of low
temperature and long-time and to propose the novelty in this research project. Traditional sous
vide or single-stage sous-vide cooking was performed at 60, 65, 70, and 75 "C for 6 and 12 h
cooking period, while novel or two-stage sous-vide was sequentially cooked at 45 and 49 "C
for 3 h, and 60, 65, 70, and 75 "C for either 3 or 9 h. Physicochemical properties (tenderness,
color, and water retention) and taste attributes (umami, astringency, sourness, saltiness,
bitterness, and richness) were determined. To evidence the physicochemical and taste
properties, the detail investigation on total collagen content, collagen solubility, sarcoplasmic
and myofibrillar proteins solubility, elastic modulus, sarcomere length, enzyme activity,
perimysium thickness, myoglobin content, desmin degradation, proteins and lipids oxidation,
nucleotide compounds, free amino acids, equivalent umami concentration (EUe), and sensory
evaluation by an electronic tongue were carried out. From our findings, we found that both
textural properties (tenderness, color, and water retention) and palatability (umami and volatile
flavors) could not be perceived at the same temperature. The former temperature, which is at
60 "C is vital for the development of tenderness, preservation of color properties, and prevent
the higher losses. Two-stage sous-vide at 45+60 "C for 6 h was apparently exhibited the perfect
match of temperature-time which presented the lower shear force values, higher a* values, and
the lowest cooking loss as compared traditional us-vide cooking method for both goat meat
and beef. The fact that mild treatment from stepped cooking has better proteolytic activity,
longer sarcomere, higher desmin degradation, and thinner perimysium, concomitant with the
reduction in the shear strength values. Also, the novel cooking method exposed to the second
temperature was shorter cooking time than the single-stage sous-vide owing to the redder and
clear myoglobin band as well as it exhibited a higher protein solubility result ng in the ~ wer
cooking loss. The latter temperature pertains on the palatability, likely the generation of urn ami
from nucleotides and synergisms effect between inosine-5' -monophosphate (IMP), guanosine-
5'-monophosphate (GMP), and aden in =r=m nopbo phate (AMP) with amino acids
aspartic and glutamic only occurred at a higher temperature (> 70°C). In contrast, the
unwanted compound such as inosine and hypoxanthine were accumulated at 60°C, likely due
to the enzyme activity further degrade the IMP. Therefore, the desired textural properties of
goat BF and GM, and beef ST muscles have be n successfully manipulated by two-stage sous
vide cooking method. However, palatability of novel sous-vide cannot be reached at 60°C; it
requires a higher temperature to intensify the urnami attribute as evidenced by the sensory
evaluation of the electronic tongue system and confirmed by the projection of partial least
squares regression (PLS-R).
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