Correction: Przybylski et al. Can Bioelectrical Impedance Analysis (BIA) Be Used to Predict Pig’s Meat Quality In Vivo? Appl. Sci. 2022, 12, 12035

The journal’s Editorial Office and Editorial Board are jointly issuing a resolution and removal of the Journal Notice linked to this article [1], as well as an update to the original publication. Following concerns raised about the integrity of the peer-review, the Editorial Office has conducted a post-publication peer-review of this article. This process included the recruitment of a new independent reviewer and was supervised by an Editorial Board member to ensure full compliance with MDPI’s Editorial Process (https://www.mdpi.com/editorial_process).

As a result of this process, the Editorial Board member and the authors have agreed to update the following aspects of this publication:

• Review Report 2 was removed from the peer-review record and a new report was uploaded at https://www.mdpi.com/2076-3417/12/23/12035/review_report;
• Update to the Academic Editor.

The original Academic Editor listed on this publication has been removed and replaced with the Editorial Board member who conducted this post-publication review.

Based on the new review report, the authors have made the following revisions to this article [1]:

1. Changes in the Abstract Section

The Abstract has been restructured as follows:

The aim of the current study was to evaluate the potential application of bioelectrical impedance analysis (BIA) for estimating pork quality. The BIA measurements were tested on 18 live animals to predict meat quality. The absolute resultant electrical resistance (Rz) and reactance (Xc) of the body were measured with a set of disposable surface electrodes at the frequency of 50 kHz and the current intensity of 400 µA. The characteristics of meat quality, including pH measured 1 h and 24 h after slaughter, meat color parameters represented in the CIE Lab system, glycolytic potential, intramuscular fat content, and natural drip loss, were assessed using samples of the Longissimus dorsi (LD) muscle. The slaughter value of the pigs was characterized on the basis of hot carcass weight (HCW) and percent of meat in the carcass. The results showed a significant Pearson correlation between bioelectrical impedance parameter Rz and pH₁ (r = 0.48, p < 0.05). A significant Spearman correlation was shown between the color b value and the Rz/Xc/HCW ratio (r = −0.62, p < 0.05) and Xc (r = −0.51, p < 0.05), as well as in the Rz/Xc ratio with pH₁ (r = 0.48, p < 0.05). The multivariate statistical method (principal component analysis and cluster analysis) showed that bioimpedance measurements combined with meat quality traits make it possible to distinguish groups with different quality parameters. However, the relationships between them are complex and require further research.

2. Changes in the Introduction Section

The following sentences in the Introduction section have been restructured as follows:

The assessment of meat safety and quality plays an important role in the food industry, as consumers are becoming more demanding and cautious when choosing food products. Evaluating the quality and safety of pork and beef is especially important in many countries. Various techniques are used to assess meat quality, including both invasive and non-invasive techniques. Non-invasive techniques have gained popularity due to technological advancements. Instruments used to estimate the composition for the grading and classification of carcasses, in general, dissected composition as a reference. This data is usually obtained through manual dissection by a qualified group, making the process invasive, costly, and time-consuming. As a consequence, obtaining meaningful and accurate information involves an invasive method, which is often costly and time-consuming. Hence, these expensive methods that are used in research or breeding programs include large numbers of animals, and they are impossible or impractical to apply routinely in commercial operations.

Therefore, non-invasive techniques used to monitor the safety and quality of beef and pork are currently a trend in zootechnical research [4–6].

Therefore, bioelectrical impedance (BIA) can be characterized as being a technology that offers fast and simple analysis, is non- invasive, and is relatively cost-effective and objective.

Such assessments provide valuable insights into the amount of extracellular water and its relation to the total water content in an organism [19,20].

3. Changes in the Materials and Methods Section

2.1. Materials

The sentences below have been restructured and have the following wording:

The research was conducted on 18 samples obtained from Pen Ar Lan fattening pigs developed from crossbreeding between P76 boars and Naima sows.

A complete mixed diet consisting of cereal with additives—mineral and vitamins—was utilized. In the first period (25–65 kg body weight) the pigs received the following diet: 13,7 MJ ME, 169.1 g crude protein and 10.41 g lysine/kg. In the second period (65–105 kg) the finisher diet contained 13.58 MJ ME, 155.6 g crude protein and 9.42 g lysine/kg.

A new reference [27] was inserted into the following sentence:

The animals were slaughtered in accordance with the European Union Council Regulations (EC) No 1099/2009 [27].

Table 1 has been transferred before sub-section 2.2.

Previous abbreviation PG was corrected to GP in Table 1 and throughout the text.

2.2. Methods

2.2.1. The Bioelectrical Impedance (BIA)

A new reference [28] was inserted into the following sentence:

Procedures conducted during the study were carried out in accordance with the principles of the European Union (recommendation 2007/526/CE) and Polish Law on Animal Protection [28].

2.2.2. Meat in Carcass

The following abbreviations have been explained in the text: CGM (Capteur Gras/Maigre - Fat/Lean Sensor) and Longissimus dorsi (LD).

2.2.4. Color of Meat

The sentences below have been restructured and have the following wording:

The colors of meat parameters were measured within 48 h after slaughter using the Minolta CR310 (Konica Minolta, Osaka, Japan) chroma meter and were expressed using the CIE L*a*b* (L*, lightness; a*, redness; b*, yellowness) system. The measurements were made at three locations on the cross section of each piece of meat (in triplicate).

2.2.5. Drip Loss

The data from the cited publication [29] have been supplemented, and methodological details have been provided. The text after the supplements is provided as follows:

Natural drip loss was defined according to the Prange et al. [29] methodology 48 h after slaughter in duplicate. Blood was collected into tubes containing EDTA (Cortex Chemicals, Warsaw, Poland) immediately after slaughter, during the opening of the carotid artery. The collected blood was centrifuged using an MPW 350 (Med. Instruments, Poland) for 10 min at 3000 rpm (1470 g), temp. 18 °C. The resulting sera samples were frozen at −82 °C and gradually used for analysis.

2.2.6. Glycolytic Potential

Since three new references [27–29] were added after the reference [26], the numbering of the remaining references was changed in this subsection and forward.

2.2.7. Intramuscular Fat Content

For this subsection, the previous title “The Content of Intramuscular Fat” has been changed to the following: Intramuscular Fat Content.

The manufacturer of the reagent has also been added. The modified sentence now reads as follows:

The dried sample was extracted with n-hexane (analytical grade, purchased from Chempur, headquartered in Piekary Śląskie, Poland).

An additional sentence was added at the end of the paragraph:

The analysis was performed in triplicate.

2.2.8. Statistical Method

For this subsection, the following sentence was removed:

Based on the results of the analysis, three groups of samples varying in BIA and meat quality traits were identified.

The sentence below has been restructured and has the following wording:

The obtained groups were compared by using one-way analysis of variance (ANOVA).

4. Changes in the Results and Discussion Section

In the first paragraph, the sentences below have been restructured and have the following wording:

The results indicate that the animals studied were meat fatteners, producing high-quality meat.

The analysis of the obtained pH values, color brightness (L*), and natural drip loss showed that, between the samples, there were no cases of defective meat such as PSE (Pale, Soft, Exudative), DFD (Dark, Firm, Dry), or the so-called “acid meat”.

In the second paragraph, numbering of references was updated, since three references were added.

In the third paragraph, the sentences below have been restructured and have the following wording:

The results of the research showed a significant Pearson correlation between resistance (Rz) and pH₁ value r = 0.48 (p < 0.05) and a Spearman correlation between Rz/Xc ratio and pH₁ r = 0.48 (p < 0.50).

The pH₁ values reflect the intensity of post-mortem glycolysis. In cases where rapid changes occur in the meat after slaughter, a low pH is typically associated with the PSE defect [21,38].

As it has been shown in many studies, fast glycolysis is associated with an increase in muscle temperature and leads to the degradation of muscle proteins and to a lightening of their color and a reduction in water retention capacity [33,34].

In the third paragraph, numbering of references was also updated, since three references were added.

In the fourth paragraph, the sentences below have been restructured and have the following wording:

However, when the carcass starts to cool down, biochemical changes occur in the cell membranes due to rigor mortis. The carcass gradually loses its ionic gradients as temperature increases and aging progresses.

The incorrectly given abbreviation “Rs” has been replaced by “Rz” in the second sentence of the fifth paragraph, which now has the following wording:

Moreover, Alfonso et al. [44] found that the parameters assessed by BIA can be used for meat characteristics in the combination of Rz and Xc to predict intramuscular fat, demonstrating 79.3% of adjustment, while, for the physicochemical characteristics, the best adjustments were in the length of the sarcomere with 64.4% and sheer force of 60.5.

In the third sentence of the seventh paragraph, the previous abbreviation PG was corrected to GP, and now has the following wording:

The first component that explained 33.18% of a total variability is strongly negatively associated with color b* value, GP, and Xc and, on the other hand, is positive associated with IMF, Rz/X/MTC, and Rz/Xc values (Table 3 and Figure 1).

In the fourth sentence of the seventh paragraph, b* was corrected to a*, and now has the following wording:

The second component explained about 17% of total variability and was strongly associated with pH₁, pH₂₄, and color L* and a* values (Figure 1 and Table 3).

The previous abbreviation PG in both the caption of Figure 1 and in the body of Table 3 has been corrected to GP.

Also, Table 3 has been transferred after Figure 1.

The sentence “Based on the results of the analysis, three groups of samples varying in BIA and meat quality traits were identified.” has been added in the subsequent discussion in the eighth paragraph.

Figure 2 has been transferred before Table 4.

In Table 4, the previous abbreviation PG was corrected to GP.

In the ninth paragraph, the sentences below have been restructured and have the following wording:

The analysis of variance showed that the obtained cluster group differed significantly for the Rz bioimpedance trait, pH₂₄, GP, and b* color values (Table 4). The results showed that groups from cluster 1 and 2 differed significantly between traits Rz, pH₂₄, GP, and color b* values (Table 4 and Figure 2), while apart from Rz the group from cluster 3 did not differ significantly from the other two groups.

In the third sentence of the ninth paragraph, R₂ has been changed to Rz, and now reads as follows:

The meat of fatteners from cluster 1 appeared with higher R_z resistance with a better value of ultimate pH, lower glycolytic potential, and lower color b* value (Table 4).

In the ninth sentence of the ninth paragraph, pHu was changed to pH₂₄, and the abbreviation Py was removed, and now reads as follows:

They also used PCA analysis with standard technological meat quality variables and bioimpedance measurements (pH₂₄, lightness (L*), and drip loss) for the classification.

All occurrences of the previous abbreviation “PG” in the article have been replaced with “GP”.

5. Changes in the Conclusions Section

The last sentence of the second paragraph was changed as follows:

However, the relationships between these factors are complex and require further analysis.

The last paragraph of the Conclusions Section has been restructured and now reads as follows:

The research conducted suggests the potential for using bioelectrical impedance measurements to empirically estimate specific aspects of pork meat quality. However, improvements in several methodological aspects appear to be necessary.

6. Changes in the References Section

Three new references have been added to the bibliography, and they are in Sections 2.1, 2.2.1, and 2.2.5. With this correction, the order of some references has been adjusted accordingly.

27. European Union Council Regulations (EC) No 1099/2009 for the Protection of Animals at the Time of Slaughter. Available online: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32009R1099 (accessed on 1 January 2025).

28. Commission Recommendation of 18 June 2007 on Guidelines for the Accommodation and Care of Animals Used for Experimental and Other Scientific Purposes (Notified Under Document Number C(2007) 2525). Available online: https://eur-lex.europa.eu/legal-content/en/ALL/?uri=CELEX%3A32007H0526 (accessed on 1 January 2025).

29. Prange, H.; Jugrrt, L.; Scharner, E. Untersuchungen zur Muskelfleischqualität beim Schwein. Arch. Exp. Vet. Med. 1977, 31, 235–248.

The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated.