3.2 Effect of sous vide temperature and time on the quality properties of beef short ribs
The most important meat quality parameters are colour, flavour, juiciness, and tenderness (Listrat et al., 2016). Consumers judge meat freshness based on colour whereas tenderness influences their repurchasing decision (Bekhit et al., 2016; Suwandy et al., 2015b). Therefore, a processing technology, which can improve tenderness and flavour, while preserving colour and minimising loss of water, is of significant value (Kantono et al., 2019). The effect of sous vide processing parameters, temperature and time, on the meat quality parameters such as shrinkage in volume (%), cooking loss (%), CIE colour parameters, and instrumental texture parameters were assessed by full factorial two way ANOVA.
There was a significant (p < 0.05) effect of sous vide temperature and time on the decrease in volume (shrinkage) and cooking loss (Table 1). The interaction effect for both parameters were not significant (p > 0.05). The degree of shrinkage (overall mean) in the short ribs significantly (p < 0.05) increased as the sous vide temperature was increased from 60 to 70°C. Similarly, the percentage shrinkage (overall mean) of the meat significantly (p < 0.05) increased when the sous vide time was increased from 12 to 24 h; but no difference was observed between 24 and 36 h. When comparing the level of shrinkage after 12 h sous vide across the three temperatures, processing at 70°C had significantly higher (p < 0.05) shrinkage than at 60°C. After 24 h, sous vide processing at 70°C had significantly higher (p < 0.05) shrinkage than at 65 or 60°C. However, after 36 h, a significant difference in shrinkage was not observed for meat samples processed at 60, 65 or 70°C. At 60°C, shrinkage was higher after 24 and 36 h sous vide processing time compared to 12 h. However, at 65 or 70°C, no significant difference in % shrinkage between 12, 24 or 36 h was observed.
Table 1
Effect of sous vide temperature and time on physical properties of beef short ribs
Parameters
|
Temp (°C)
|
Time (h)
|
|
12
|
24
|
36
|
Overall mean
|
Shrinkage in volume (%)
|
60
|
12.45 ± 8.74abX
|
16.08 ± 7.96abXY
|
24.48 ± 8.22Y
|
17.67 ± 9.52a
|
65
|
17.94 ± 13.07bc
|
23.62 ± 7.28ab
|
25.24 ± 3.30
|
22.27 ± 9.11b
|
70
|
22.86 ± 9.20cX
|
33.27 ± 6.71bY
|
29.41 ± 9.17XY
|
28.51 ± 9.24c
|
Overall Mean
|
17.75 ± 11.03X
|
24.33 ± 10.07Y
|
26.38 ± 7.83Y
|
|
Cooking loss (%)
|
60
|
12.78 ± 2.15aX
|
15.87 ± 2.53aY
|
18.08 ± 1.47aY
|
15.58 ± 3.00a
|
65
|
15.51 ± 3.07abX
|
21.08 ± 1.52bY
|
21.33 ± 2.61bY
|
19.30 ± 3.63b
|
70
|
18.23 ± 4.25bX
|
23.15 ± 3.58bY
|
24.78 ± 2.30cY
|
22.05 ± 4.39c
|
Overall Mean
|
15.51 ± 3.90X
|
20.03 ± 4.05Y
|
21.39 ± 3.49Y
|
|
Soluble collagen (%)
|
60
|
20.19 ± 4.50b
|
20.00 ± 3.33b
|
19.31 ± 2.94c
|
19.83 ± 3.48
|
65
|
23.36 ± 3.67ab
|
21.16 ± 5.39b
|
27.05 ± 4.16b
|
23.85 ± 4.91
|
70
|
28.24 ± 8.27aY
|
35.29 ± 6.39aX
|
40.24 ± 4.39aX
|
34.59 ± 8.00
|
Overall mean
|
23.93 ± 6.49
|
25.48 ± 8.66
|
28.86 ± 9.59
|
|
Myofibrillar fragmentation index (MFI)
|
60
|
109.15 ± 14.46bY
|
117.47 ± 14.65cXY
|
129.29 ± 10.07bX
|
118.85 ± 15.44cY
|
65
|
129.42 ± 18.51a
|
138.54 ± 15.47b
|
139.53 ± 15.90b
|
135.83 ± 16.75bY
|
70
|
139.86 ± 15.05aY
|
163.56 ± 14.96aX
|
176.43 ± 12.53aX
|
159.95 ± 20.63aX
|
Overall mean
|
126.14 ± 20.24Z
|
139.85 ± 24.03Y
|
148.63 ± .23.96X
|
|
Values presented are means ± SD (n = 10 for cooking loss, shrinkage in volume and MFI, n = 7 for collagen solubilized) |
a−c values with different letters within in the same column differ significantly (p < 0.05) |
X−Z values with different letters within the same row differ significantly (p < 0.05) |
Values without the superscripts do not differ significantly |
There was a significant (p < 0.05) increase in cooking loss (%) as sous vide temperature and time were increased. The overall mean cooking loss (%) of short ribs sous vide processed at 70°C was significantly higher (p < 0.05) than ribs heated at 65 or 60°C; and at 65°C cooking loss was significantly higher than at 60°C. This temperature effect was also observed in meat processed for 12 h. However, after 24 h SV the only significant cooking loss effect was observed between meats processed at 70°C and 65°C with meat processed at 60°C and after 36 h no temperature effect on cooking loss was observed. Meat processed at 24 and 36 h had a significantly higher cooking loss than meat sous vide processed for 12 h. The cooking losses found in this study were lower compared to other studies on tough meat cuts, even at 70°C (Bhat et al., 2020; Christensen et al., 2013; Ismail et al., 2019; Rinaldi et al., 2014). Bhat et al. (2020) reported cooking loss (%) of 28.67 ± 0.61 in beef semitendinosus muscle of dairy cows. Christensen et al. (2013) reported 26.6 and 25.9% cooking loss at 60°C for 10 h for cows (4–6 years old) and young bulls (10–12 months), respectively. Ismail et al. (2019) reported 29.07% cooking loss at 60°C for 12h for semitendinosus muscles of Hanwoo steers (24–32 months). Rinaldi et al. (2014) reported 38.9% cooking loss at 75°C for 36 h for beef semitendinosus muscle. However, the cooking losses in this study may have been reduced due to limited cooking loss of the bone present in the short rib sections.
The shrinkage in volume reduced the water holding capacity (WHC) of the meat and increased the cooking loss, which is associated with a decrease in juiciness and succulence (Arroyo, Eslami, et al., 2015; Dominguez-Hernandez et al., 2018). The WHC of meat also affects its texture, tenderness, and flavour (Arroyo, Eslami, et al., 2015; Roldán et al., 2013). The shrinkage in volume and cooking loss were positively correlated (Pearson correlation coefficient 0.546, p < 0.01). Both significantly increased when sous vide temperature and cooking time were increased. The likely mechanism for the higher cooking loss at higher sous vide temperature and longer cooking time was the increased myofibrillar shrinkage and contraction. This phenomenon decreased the intracellular space and volume between strands of actin and myosin of sarcomere, and this consequently increased the expulsion of intracellular water (Baldwin, 2012; Bertram et al., 2006; Bertram et al., 2002; Cheng & Sun, 2008; Micklander et al., 2005; Suwandy et al., 2015a). Intracellular water accounts about 70–75% of total water content of meat (Bertram et al., 2006). Furthermore, the higher the cooking temperature will be the greater the denaturation of myofibrillar proteins will be. As myofibril proteins hold the major proportion of water in meat, their denaturation, especially of myosin, reduces the meat’s water holding capacity (Wiklund et al., 2001). Bertram et al. (2006) also showed a significant relationship between the increase in denaturation of myofibrillar proteins, seen by major changes in the FT-IR spectroscopic bands in the amide I-region (1700 − 1600 cm− 1) and broadening of T21 (35–50 ms) NMR relaxometry peak, and a decrease in myofibrillar water during heating.
The effect of sous vide temperature (p < 0.001) and time (p = 0.008) on the proportion of soluble collagen relative to total collagen in the ribs were significant as was the interaction between sous vide temperature and time (p = 0.01) (Table 1). Therefore, the effect of temperature on soluble collagen of short ribs was affected by the level of processing time and vice versa. The soluble collagen of ribs cooked at 70°C had significantly higher than when cooked at 65 or 60°C; and in addition, short ribs cooked at 65°C were significantly higher than when cooked at 60°C. This effect was observed for ribs sous vide for 36 h but in ribs cooked for 24 h soluble collagen was only significantly higher at 70°C than the other temperatures, and at 12 h soluble collagen was significantly lower at 60°C than at 65°C or 70°C. Similarly, the effect of sous vide temperature (p < 0.001) and time (p < 0.001) on the MFI were significant but the interaction term was not significant (p > 0.05) (Table 1). The MFI values increased with an increase in sous vide temperature and time.
The tenderness of meat and meat products has a dramatic impact on consumer’s repurchasing decisions (Bolumar et al., 2013). The tenderness of a meat cut depends on the amount of connective tissue present, the extent of proteolysis of the myofibrillar proteins, as well as animal (age, breed), environmental, and genetic factors (Anderson et al., 2012). The effect of sous vide temperature and time on tenderness and texture parameters of short ribs instrumental parameters were assessed using WBSF and TPA parameters such as hardness, adhesiveness, cohesiveness, springiness, gumminess, chewiness, and resilience (Table 2). There was a significant effect of temperature (p < 0.05) on WBSF, hardness, cohesiveness, gumminess and chewiness; and a significant effect of time (p < 0.05) on WBSF, hardness, adhesiveness, cohesiveness, springiness, gumminess chewiness and resilience of sous vide ribs.
WBSF (N), which is correlated to the shearing and compression during eating meat, was significantly affected by temperature and time (p = 0.026 and p < 0.001, respectively) (Table 2). However, a significant time – temperature interaction was observed (p = 0.010) indicating that the WBSF did not change the same way with temperature as time was changed. At sous vide time of 12 h, only ribs processed at 60°C had significantly (p < 0.05) lower WBSF value than at 65 and 70°C and after 24 h sous vide processing, no significant difference between the three temperatures were observed. However, at 36 h sous vide, a significant difference in WBSF was observed between ribs processed at 60 and 70°C. However, WBSF values at all temperature and time combinations were lower than the threshold level for beef to be described as tender. Destefanis et al. (2008) and Dufey et al. (2017) concluded separately from consumer testing that beef meat with WBSF < 42.87 N and < 32.57 N (≤ 3.3 kg force), respectively can be termed tender.
The trends observed for TPA hardness values of sous vide ribs were similar to the WBSF values. In TPA, hardness is maximum force encountered by the first depression of the probe, which is analogous to the hardness encountered upon the first bite; however hardness perception continues during the subsequent mastication process (Nishinari & Fang, 2018). As with WBSF a significant temperature-time interaction (p = 0.022) was observed for hardness values. The hardness was significantly lower after sous vide of ribs for 24 and 36 h and at 70°C compared to sous vide for 12 h, at 60°C or 65°C (Table 2). No difference was observed in hardness between ribs sous vide for 12 h at the three sous vide temperatures. However, after sous vide for 24 or 36 h the hardness of meat sous vide at 70°C was significantly lower than for sous vide at 60°C.
Significantly lower WBSF values for sous vide treatment at 60°C than at 65 or 70°C after 12 h may be associated with lower degree of myofibrillar protein denaturation and lower level of shrinkage and cooking loss. It is well documented that as the cooking temperature increases the degree of myofibrillar proteins denaturation increases, as does the shrinkage of the sarcomere reducing its volume thereby resulting in meat becoming tough and dry. Higher cooking losses resulted in the tough meat (Roldán et al., 2013). The lower WBSF and hardness values in sous vide ribs after processing for 36h at 70°C compared to 60°C might be due to the higher level of solubilisation and gelation of collagen and sarcoplasmic proteins even though the extent of denaturation may be similar.
Table 2
Effect of sous vide temperature and time on instrumental textural parameters of beef short ribs
Parameters
|
Temp
(°C)
|
Time (Hours)
|
|
12
|
24
|
36
|
Overall mean
|
Warner Bratzler shear force (WBSF)
|
60
|
21.02 ± 5.64bX
|
19.35 ± 4.24XY
|
17.59 ± 4.46aY
|
19.32 ± 4.97
|
65
|
24.68 ± 5.99aX
|
21.09 ± 5.60Y
|
17.08 ± 4.51abZ
|
20.95 ± 6.19
|
70
|
24.41 ± 5.79aX
|
18.29 ± 5.02Y
|
14.23 ± 5.22bZ
|
18.98 ± 6.76
|
Overall mean
|
23.37 ± 5.98
|
19.57 ± 5.06
|
16.30 ± 4.92
|
|
TPA Hardness (N)
|
60
|
22.94 ± 11.44
|
21.96 ± 6.93a
|
20.81 ± 7.53a
|
21.90 ± 8.85
|
65
|
21.12 ± 10.64
|
19.66 ± 5.88ab
|
22.05 ± 6.91a
|
20.94 ± 8.08
|
70
|
21.51 ± 8.64X
|
16.90 ± 6.25bY
|
15.26 ± 4.03bY
|
17.89 ± 7.06
|
Overall mean
|
21.86 ± 10.27
|
19.51 ± 6.66
|
19.37 ± 6.96
|
|
TPA Adhesiveness (N.sec)
|
60
|
-0.02 ± 0.03
|
-0.02 ± 0.04
|
-0.03 ± 0.05
|
-0.03 ± 0.04
|
65
|
-0.02 ± 0.06
|
-0.02 ± 0.04
|
-0.03 ± 0.05
|
-0.03 ± 0.05
|
70
|
-0.03 ± 0.05Y
|
-0.03 ± 0.05Y
|
-0.06 ± 0.09X
|
-0.04 ± 0.07
|
Overall mean
|
-0.03 ± 0.05Y
|
-0.02 ± 0.05Y
|
-0.04 ± 0.07X
|
|
TPA Cohesiveness
|
60
|
0.45 ± 0.07aX
|
0.43 ± 0.05aX
|
0.38 ± 0.08aY
|
0.42 ± 0.07
|
65
|
0.43 ± 0.09abX
|
0.34 ± 0.08bY
|
0.36 ± 0.04aY
|
0.38 ± 0.08
|
70
|
0.40 ± 0.08bX
|
0.32 ± 0.06bY
|
0.29 ± 0.05bZ
|
0.33 ± 0.08
|
Overall mean
|
0.42 ± 0.08
|
0.36 ± 0.08
|
0.34 ± 0.07
|
|
TPA Springiness
|
60
|
0.61 ± 0.09
|
0.59 ± 0.08
|
0.58 ± 0.11
|
0.59 ± 0.09
|
65
|
0.63 ± 0.10
|
0.62 ± 0.09
|
0.59 ± 0.10
|
0.61 ± 0.10
|
70
|
0.68 ± 0.11X
|
0.60 ± 0.13Y
|
0.58 ± 0.09Y
|
0.62 ± 0.12
|
Overall mean
|
0.64 ± 0.10
|
0.60 ± 0.10
|
0.58 ± 0.10
|
0.61 ± 0.10
|
TPA Gumminess
|
60
|
10.39 ± 5.65X
|
9.67 ± 3.79aXY
|
8.33 ± 3.99aY
|
9.46 ± 4.60
|
65
|
9.47 ± 5.88X
|
6.93 ± 3.02bY
|
8.06 ± 2.92aXY
|
8.15 ± 4.28
|
70
|
8.73 ± 4.67X
|
5.63 ± 2.63bY
|
4.42 ± 1.43bY
|
6.26 ± 3.67
|
Overall mean
|
9.53 ± 5.43
|
7.41 ± 3.58
|
6.94 ± 3.45
|
|
TPA Chewiness (N)
|
60
|
6.41 ± 3.67X
|
5.72 ± 2.44aXY
|
5.02 ± 2.81aY
|
5.72 ± 3.05
|
65
|
6.14 ± 4.13X
|
4.28 ± 1.89bY
|
4.84 ± 2.04aXY
|
5.09 ± 2.96
|
70
|
5.97 ± 3.36X
|
3.48 ± 1.77bY
|
2.51 ± 0.81bY
|
3.99 ± 2.66
|
Overall mean
|
6.18 ± 3.71
|
4.49 ± 2.24
|
4.13 ± 2.35
|
|
TPA Resilience
|
60
|
0.27 ± 0.05aX
|
0.22 ± 0.04aY
|
0.19 ± 0.04aZ
|
0.23 ± 0.05
|
65
|
0.23 ± 0.06bX
|
0.17 ± 0.04bY
|
0.17 ± 0.03aY
|
0.19 ± 0.05
|
70
|
0.22 ± 0.05bX
|
0.15 ± 0.03cY
|
0.13 ± 0.02bZ
|
0.16 ± 0.05
|
Overall mean
|
0.24 ± 0.06
|
0.18 ± 0.05
|
0.16 ± 0.04
|
0.19 ± 0.06
|
Values presented are means ± SD (n = 30 for WBSF and n = 50 TPA parameters, with 10 short ribs with 3 and 5 samples per meat pieces for WBSF and TPA, respectively) |
a−c values with different letter within in the same column differ significantly (p < 0.05) |
X−Z values with different uppercase letters within the same row differ significantly (p < 0.05) |
Values without the superscripts do not differ significantly |
Similar results were observed by Vaudagna et al. (2002) and García-Segovia et al. (2007). Vaudagna et al. (2002) reported lower WBSF at 65°C than at 50°C. García-Segovia et al. (2007) reported a significant decrease in WBSF with an increase in sous vide temperature from 60 to 80°C. This was credited to moist in-pack environment and overpressure created by saturated stream resulting in improved heat transfer, which led to greater unfolding and gelation of sarcoplasmic protein and myofibrillar protein as well as increased breakage of thermolabile bonds of triple helix structure of collagen, which increased its solubilisation (García-Segovia et al., 2007; Tornberg, 2005). This is supported by the observation that the percentage of soluble collagen was significantly higher (p < 0.05) at 70°C than at 60°C after 36 h sous vide processing (Table 1). In addition, Zielbauer et al. (2016) reported that the denaturation temperature and enthalpy is lower than the dry heating denaturation temperature and enthalpy of myofibrillar proteins during moist heating techniques, like sous vide emphasising that the same level of denaturation could be achieved at lower temperatures. The importance of solubilisation of collagen for enhancement of tenderness can be stressed from the observation by Alahakoon et al. (2018). They did not observe the significant increase in the amount of soluble collagen of beef brisket when sous vide temperature was increased from 60°C to 70°C processed for same time of 24 h and no subsequent decrease in WBSF values at that sous vide condition.
Meat tenderness is not only affected by the distribution and amount of connective tissues but also affected by the overlapping and disintegration of the myofibrillar structure (Aroeira et al., 2020; Sawdy et al., 2004). It is also stated that increase in tenderness is also due to higher degree of meat proteolysis indicated by MFI (Aroeira et al., 2020; Culler et al., 1978 ). The results discussed in the current study also agree with the above argument. Significantly lower WBSF and TPA hardness and significantly higher MFI was observed with increase in sous vide temperature and time.
For adhesiveness, which is the force required to separate the plunger and meat (Nishinari & Fang, 2018) indicating meat stickiness due to increased mass transfer towards the surface, short ribs sous vide for 36 h had significantly lower values than that SV for 12 or 24 h. This difference in overall mean was due to the difference in adhesiveness at sous vide time of 36h at 70°C which was in significantly lower than 12 and 24h sous vide at 70°C.
TPA cohesiveness, which relates to how much the meat regains its structure and is associated with the integrity of meat was found to have significant time (p < 0.001), temperature (p < 0.00) and time- temperature interaction (p = 0.035). Regardless of whether meat was sous vide at 60, 65 or 70°C, cohesiveness was significantly lower at 36 h than after 12h. When assessing the effect of temperature at the same processing time, sous vide at 70°C the cohesiveness is significantly lower than at 60°C for 12, 24 or 36 h. These results indicate that the textural coherence and integrity decrease at SV temperature greater than or equal to 65°C and at SV time of 36 h.
Springiness, previously called elasticity, of sous vide ribs, which is the rate at which deformed ribs return to its undeformed condition after the deforming force is removed, displayed a significant sous vide time-temperature interaction (p = 0.035) in addition to the significant (p < 0.001) time effect. Short ribs processed for 24 or 36 h at 70°C had significantly lower springiness than that cooked for 12 h. Similarly, the sous vide time-temperature interaction was also significant (p < 0.05) for TPA gumminess. Short ribs sous vide processed for 24 or 36 h had significantly gumminess lower than 12 h and these differences were also observed at 60, 65 or 70°C. Gumminess of ribs sous vide at 70°C was significantly lower than at 65 or 60°C after sous vide for 12 h. This difference was observed in ribs sous vide for 24 or 36 h. Gumminess, energy required to disintegrate a semisolid food product to a state ready for swallowing (Nishinari & Fang, 2018), is derived from TPA hardness and cohesiveness. Therefore, based on the findings for hardness and cohesiveness, springiness and gumminess will decrease as the sous vide temperature is increased and sous vide time lengthened.
TPA chewiness is calculated from the primary parameters of hardness, cohesiveness, and elasticity (Nishinari & Fang, 2018). As the temperature was increased from 60°C to 70°C chewiness significantly decreased and similarly increasing the sous vide time from 12 h to 24 or 36 h significantly reduced the chewiness. At longer sous vide times of 24 or 36 h, higher sous vide temperature of 70°C had significantly lower chewiness than at 60°C. This effect was not observed at a sous vide time of 12h, potentially reflecting the significant SV time and temperature interaction (p = 0.011). The same trends were observed for the resilience values where they significantly decreased in ribs sous vide for longer times at higher temperatures
Meat colour is a critical quality attribute as the visual appearance of raw meat influences the consumer’s decision to purchase and the acceptance of the cooked meat (Arroyo, Lascorz, et al., 2015). The colour of fresh meat depends on the content and physicochemical state of myoglobin, i.e. purple (reduced myoglobin), red (oxymyoglobin), and brown (metmyoglobin) (Abril et al., 2001). The effect of sous vide temperature and time on CIE L*, a*, b*, Chroma (\({C}^{*}=\sqrt{{a}^{*2}+{b}^{*2}}\)), and hue angle (\({\text{h}=\text{tan}}^{-1}\frac{{b}^{*}}{{a}^{*}}\)) are summarised in Table 3. Significant (p<0.05) sous vide time and temperature effects were observed for L*, significant effect of time were observed for h, and significant (p < 0.05) temperature effects for b*, C*, Δb* and ΔE*. An interaction of sous vide time and temperature on the colour of ribs was observed for C*. These were the only colour parameters for which significant effects were observed. L* values of the sous vide rib surface were significantly higher at 60°C than at 65 or 70°C and ribs sous vide at 65°C higher than at 70°C. Similarly, 12 h sous vide had significantly higher L* values than for 24 or 36 h sous vide. The increase in the change in lightness (ΔL*), which is a comparison between the meat before and after sous vide were significantly higher at 60°C than at 65 or 70°C. The higher lightness associated with ribs sous vide at lower temperature and shorter times is due to higher amount of free water on the surface (Sánchez del Pulgar et al., 2012), which is consistent with the cooking loss results.
Table 3
Effect of sous vide temperature and time on CIE L*a*b*, h and C* colour parameters of beef short ribs
Parameters
|
Temp (°C)
|
Time (Hours)
|
|