This fortnightly newsletter was curated and edited by: J.W. Holloway and his Team
Volume II of Red Meat Science and Production addresses the character of red meat that can be sensed at the time of consumption. The consumer is conditioned to the eating experience, and his/her expectations are set before the actual eating experience through the senses of sight and smell. Therefore, the first discussion of the intrinsic character of red meat that is in this chapter is concerned with, perhaps the threshold sensation setting the stage for the eating experience, aroma. This chapter reviews the scientific literature concerning the consumer’s perception of red meats as delivered through the air, the chemical nature of the red meat responsible for this perception, and production system elements that may be sensitive to this perception.
Raw meat has a little aroma and a bloodlike taste (Crocker 1948; and Bender and Ballance, 1961). Aroma, therefore, is only sensed after the meat is cooked. The sensation of aroma is a component of flavor. The nose senses aroma, and the tongue senses taste; the composite sensation is called flavor. But, because the aroma is sensed prior to the other sensory attributes of red meat, it is discussed first; howbeit, it is further discussed as a component of flavor.
Although the aroma is an important integral part of the eating experience of red meat (especially for lamb and mutton), little has been reported concerning the biochemistry of aroma or the production system elements impacting aroma. Perhaps, the reason for this is that, by definition, the aroma is the result of volatiles released from the meat during the cooking process. Volatile compounds are elusive and difficult to capture and study. It is natural, however, to assume that, since raw meats have little or no aroma and that cooking releases the volatiles causing aroma, the Maillard reaction is probably involved. Ribose, as a substrate in the Maillard reaction, and through its role in decreasing the formation of lipid oxidation products, is a significant contributor to the roasted and meaty aroma and umami (Farmer, Hagan, and Paraskevas, 1999). Because of their relatively high concentrations, glucose and glucose-6-phosphate may have equal or more importance for roasted and meaty aromas than the 5-carbon reducing sugars, ribose, and ribose-5-phosphate (Farmer, Kennedy, and Hagan, 2009).
Aroma compounds in cooked beef have been evaluated and ranked according to their intensities and potential contributions to cooked beef flavors (Farmer and Patterson, 1991; Gasser and Grosch, 1988; and Specht and Baltes, 1994). However, the magnitude of flavor dilution factors differed between studies because of differences in extraction and concentration rates. The primary contributors are methional, 2-ethyl-3,5- dimethyl pyrazine, 2-propyl-3-methyl pyrazine, 2-methyl-3-furanthiol, bis(2-methyl-3-furyl) disulfide, 2-acetyl-1-pyrroline, 2-acetylthiazole, 2(E)-octenal, 2(E)-nominal, 2(E),4(E)-nonadienal, 2(E),4(E)-decadienal, 1-octen-3-one, 2-octanone, 2-decanone, 2-dodecanone, phenylacetaldehyde, β-ionone, and 2-furfuryl 2-methyl-3-furyl disulfide which have been reported to be active aroma compounds in cooked beef (Khan, Jo, and Tariq, 2015). “Mutton” aroma in cooked sheep meat is caused by the formation of short branched-chain fatty acids (BCFAs) as an implication of diet (Khan, Jo, and Tariq, 2015). Animals fed a grain-based finishing diet showed higher concentrations of BCFA compounds (Young et al, 2003; Young and Braggins, 1998).
Production System Elements (Critical Control Points)
Animal genetics has been reported to influence beef aroma. Wagyu beef has a sweet and fatty aroma known as “Wagyu beef aroma,” which is preferred by Japanese consumers (Motoyama, Sasaki, and Watanabe, 2016). This aroma is not present after slaughter but is generated during storage in the presence of oxygen (Matsuishi, Fujimori, and Okitani, 2001). The optimum cooking temperature to generate this aroma is 80°C which is consistent with the optimum temperature for cooking typical Japanese Wagyu dishes sukiyaki and shabushabu (Motoyama, Sasaki, and Watanabe, 2016). One of the candidate compounds possibly contributing to this aroma is γ-nonalactone, which has a coconut- or peach-like aroma and an unusually high flavor dilution factor (Matsuishi et al., 2004). Also, alcohols and aldehydes with fatty aroma and diacetyl and acetoin with butter-like aroma appear to contribute to the fatty sensation associated with Wagyu beef aroma (Matsuishi et al., 2004).
Many volatile compounds are the derivatives of fat; therefore, the character of the fat has a vital role in aroma (Motoyama, Sasaki, and Watanabe, 2016). Another production system element that has been implicated in the aroma development of beef is the method of slaughter. Önenc and Kaya (2004) reported that stunning improved the odor of beef and, therefore, Halal and Kosher beef might be expected to have less aroma than other beef. Koshered meat has been reported to develop objectionable odors during refrigeration (Holzer et al, 2004; and Hayes et al, 2015). The packaging method also impacts red meat aroma. While High Oxygen, Modified Atmospheric Packaging (HIOX MAP) apparently improves color, it also increases lipid oxidation leading to off-odor in fresh red meats (Campo et al., 2006; Kim et al., 2010c; Mancini et al., 2010a; O’Grady et al., 2000; and Resconi et al., 2012).
For several years, the taste of meat has been researched but its success is a difficulty owing to the structure of the meat matrix. However, substantial progress has been made in discovering and quantifying the signature meat aroma compounds in recent years. Through the use of olfactometry and mass spectrometric techniques, thousands of volatile compounds have been identified as volatile ingredients. Included in this was the primary influence of sulfur containing meat aroma ingredients, but due to potential synergies between aroma elements, the contribution of other aroma compounds should not be overlooked. In addition, several different aspects influence taste, and both should be taken into account if cooked and processed meat consistency is to be increased. This understanding of the meat taste is highly beneficial in making savory flavors. Although other features, such as sensory flavor perception, the impact of the meat matrix on flavor associations and the online tracking of flavor release should be taken into consideration to relate in vivo findings to the attitude of the user. Both of these things help to explain the complexity of the experience of taste. Lastly, the movement towards demands on natural taste ingredients in foods makes it possible for scientists to search for precursors and processes in biotechnology to generate natural meat tastes.