Effect of postmortem aging time on flavor profile of stewed pork rib broth

Significance of the topic

Flavor quality is a critical driver of consumer acceptance for meat products and derived preparations such as pork rib broth. Postmortem proteolysis and biochemical transformations during chilled storage modify key flavor precursors, influencing the taste and aroma of the final cooked product. Understanding how aging time affects both nonvolatile taste compounds and volatile aroma constituents enables optimization of processing conditions to enhance sensory attributes and product consistency.

Objectives and overview of the study

This study aimed to evaluate the impact of postmortem aging periods (1, 3, and 7 days at 4 °C) of pork spare ribs on the flavor profile of resulting stewed rib broth. Specific aims were:

• Quantify changes in free amino acids, nucleic-acid related compounds and organic acids in broth.
• Profile volatile compounds by GC-MS.
• Assess overall taste and aroma using electronic tongue, electronic nose, and trained sensory panel.

Methodology and instrumentation used

Nonvolatile compounds were analyzed by:

• Automatic amino acid analyzer (Hitachi L-8900) after sulfosalicylic acid extraction.
• HPLC-DAD for nucleotides and organic acids using C18 and Atlantis T3 columns, respectively.

Volatile profiling employed headspace solid-phase microextraction followed by GC-MS (Thermo TSQ Quantum XLS) on a DB-WAX column. Aroma patterns were captured by an 18-sensor electronic nose system (Alpha MOS αFox 4000). Taste fingerprints were recorded with an electronic tongue (Alpha MOS ASTREE) featuring cross-selective sensors. A ten-member trained panel conducted 9-point hedonic scoring for clarity, taste intensity and aroma.

Main results and discussion

Nonvolatile taste precursors:

• Free amino acids increased significantly with aging, notably glutamate (umami), alanine and glycine (sweet).
• Key nucleotides (5′-IMP, 5′-GMP, 5′-AMP) decreased, while hypoxanthine rose, reflecting ongoing ATP degradation.
• Succinic acid, a potent sour/umami contributor, increased three-fold, whereas citric acid declined.
• Equivalent umami concentration peaked at 3 days, correlating with sensory taste scores.

Volatile aroma compounds:

• Aldehydes dominated (70–80% of volatiles), with hexanal, nonanal, octanal and heptanal as major odorants.
• Total volatile content and aldehyde concentrations were stable across aging times, although minor alcohols, ketones and esters showed slight variations.

Instrumental pattern recognition:

• Electronic tongue PCA differentiated broths by aging time, reflecting taste changes.
• Electronic nose PCA and GC-MS demonstrated no marked aroma shifts during aging.
• Sensory panel confirmed enhanced taste intensity and clarity after 3 and 7 days, with aroma intensity unchanged.

Benefits and practical applications of the method

Combining targeted chemical analysis with electronic sensors and sensory evaluation offers a comprehensive toolkit for quality control in meat processing. The insights into optimal aging durations help producers:

• Maximize savory taste and overall palatability of rib broths.
• Standardize processing to deliver consistent flavor profiles.
• Inform product development and shelf-life management based on flavor precursor dynamics.

Future trends and potential applications

Further research may explore:

• Comparative effects of freezing vs. chilling on broth flavor precursors.
• Application of advanced metabolomics and lipidomics to map complex flavor networks.
• Use of real-time electronic tongue/nose systems in process monitoring.
• Extension to other meat cuts, mixed-ingredient broths and novel aging techniques.

Conclusion

Postmortem aging of pork ribs strongly influences nonvolatile taste compounds, enhancing broth savoriness via increased free amino acids and succinic acid at the expense of nucleotides. In contrast, volatile aroma profiles remain largely unaffected. A 3-day chilled aging period optimizes umami intensity without altering aroma, offering a practical guideline for improving quality and consistency of stewed pork rib broth.

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