Based on Korean historical records, Korean native cattle have lived on the Korean peninsula since the fourth century (Kim and Lee, 2000). The Korean native cattle have traditionally included four cattle breeds, composed of three coat color patterns (Jo et al., 2012; Lee et al., 2014). The three color patterns are a brown or red, a black-striped brown, and two black color breeds (Lee et al., 2014). The Korean native cattle breeds were used as working cattle until the 1960s. With the development of farming technology, Korean native cattle became used as beef meat (Kim and Lee, 2000; Lee et al., 2014). The well-known Hanwoo cattle breed has the largest population in South Korea. The other three non-brown or red color breeds have smaller populations. Among the minor breeds, Jeju black cattle live only on Jeju Island (Han et al., 2011).
Jeju black cattle beef were a rare gift given to the king in the Chosun era. The king only could eat that beef on his birthday, New Year’s Day, and on Memorial Day of the royal family. Presently, Jeju black cattle beef is available at specialty butcher shops due to development of production technology. However, people recognize Hanwoo as the representative beef meat cattle of Korea and favor it for roasting. Wagyu is the popular Japanese cattle breed for its texture, flavor, and tenderness. The roasted beef is a popular meat food in South Korea. Consumers prefer the palatability and flavor from its marbled fat (Frank et al., 2016). Because of these preferences, beef consumption has increased every year (Korea Meat Industries Association, 2000). The flavor of beef meat is derived from its fatty acid content (Frank et al., 2016; Lorido et al., 2015). Fatty acid content is an important factor in the beef meat industry (Frank et al., 2016; Melton et al., 1982). The type and amount of fatty acids in beef meat have a great effect on quality perception and sensory characteristics, such as taste, tenderness, and flavor (Enser et al., 1996; Frank et al., 2016; Hocquette et al., 2014).
Fatty acids are categorized into saturated fatty acids (SFA) and unsaturated fatty acids (UFA). The SFAs are composed of single bond fatty acid chains, and therefore are usually solids room temperature. On the other hand, UFAs are generally liquids at room temperature because their molecular structure is not linear. Moreover, a previous study reported that the UFAs have a key role in meat flavor (Elmore et al., 1999). In another study, the fatty acid and amino acid characteristics of cattle breeds, including Hanwoo were reported (Hwang and Joo, 2017). However, a comparison of these characteristics between Hanwoo and Jeju black cattle was not performed. Through identification of differences between these two Korean traditional cattle breeds the quality of Korean beef meat production can be enhanced. In this study, we examined the fatty acid and amino acid characteristics of Hanwoo and Jeju black cattle beef and suggest the unique nutritional characteristics of Jeju black cattle beef that have made it a popular meat choice in Korea.
Materials and Methods
A total of 62 cattle of the Hanwoo (n=28; females (F)=11, castrated males (CM)=16), Jeju black cattle (n=25; F=8, CM=17), and Wagyu (CM=10) breeds were used in this study. Hanwoo and Jeju black cattle were raised in the same farm and same feeding condition and slaughtered on Jeju Island. After slaughter, the longissimus dorsi (LD) muscles were sampled and cut into 2.5 cm thick steaks. The muscle samples were vacuum-packed and stored at 4°C until 41 days postmortem. Wagyu beef was commercial meat imported from Australia and also vacuum-packed and stored at 4°C until 41 days postmortem.
To compare the nutritional content, fatty acid and amino acid composition was measured. The fatty acids and amino acids were measured by gas chromatography-flame ionization detector (GC). A total of 37 fatty acids were measured using 25 g of muscle collected from each animal. The samples were methylated with 14% BF3-Methanol and diluted using 1 mL isooctane. The column used was 100 mm×0.25 mm×0.2 μm (Supelco TMSP-2560, Sigma-Aldrich®, USA). The carrier gas was nitrogen at 0.8 mL/min. The injector and the detector were tested at 240°C and 285°C each. The split ratio was varied between 100 and 1. The standard solution of fatty acids was a 0.1 g fatty acid methyl ester mixture (SUPELCOTM 37Component FAME Mix, Bellefonte, PA, USA) diluted to 100 mg/mL in isooctane. The GC retention time of the standard solution is presented in Table S1 and Table S2.
The association between cattle traits were measured using the general linear model (GLM) procedure (SAS; SAS Institute, Inc., USA). To compare the mean values between the cattle breeds, Duncan’s multiple range test was used. A value of p<0.05 was considered statistically significant.
Results and Discussion
In this study, we performed fatty acid composition analyses of Hanwoo, Jeju black cattle, and Wagyu breed using a GC method. The fatty acids compositions are presented in Table 1. Palmitic acid showed a significant difference between Hanwoo and Jeju black cattle. Hanwoo beef had much more palmitic acid than Jeju black cattle (p<0.001). In a previous study, palmitic acid, an SFA, had a negative effect on beef meat flavor (Westerling and Hedrick, 1979). Consumers prefer the good flavor of fatty acids in beef fat marble (Kim et al., 1999). Therefore, Jeju black cattle with relatively less palmitic acid, is a popular choice of consumers. There was a significant difference in oleic acid and linoleic acid among breeds (p<0.05). Jeju black cattle showed the highest proportion of oleic acid and contained more oleic acid and linoleic acid than Hanwoo. These fatty acids are representative fatty acids in beef meat (Dryden and Maechello, 1970; Enser et al., 1996; Westerling and Hedrick, 1979). Oleic acid has been reported to have a role in good meat flavor and savory taste (Dryden and Maechello, 1970). The savory taste and flavor are important traits for meat consumers, thus a rich oleic acid content can make meat taste better.
Linoleic acid was reported to cause a negative flavor in meat (Westerling and Hedrick, 1979). Jeju black cattle beef may be less flavorful than Hanwoo meat because of linoleic acid, but the absolute amount of linoleic acid is less than the palmitic acid amount. Therefore, its effect to decrease flavor in Jeju black cattle beef could be expected to be small. Jeju black cattle showed a lower proportion of SFAs than Hanwoo (p<0.001). SFAs are known to be the main culprit in hyperlipidemia and hypercholesterolemia (Bingham et al., 2002; Micha and Mozaffarian, 2010; Mozaffarian et al., 2010). These conditions are reported to cause cardiovascular disease and diabetes (Bingham et al., 2002; Micha and Mozaffarian, 2010). Therefore, lower proportions of SFAs are more preferable. In addition, the consumers’ preference has changed from flavor to health (Joo et al., 2017). Therefore, the lower SFAs in Jeju black cattle beef are likely to be preferred by consumers.
In contrast to the SFA ratio, the UFA ratio, including mono-UFA (MUFA) and poly-UFA (PUFA) was higher in Jeju black cattle than Hanwoo (MUFA: p<0.01, PUFA: p<0.05). The UFA ratio is also known to be associated with better health (Cross et al., 2007; Kontogianni et al., 2008). In previous studies, a high UFA ratio prevented cardiovascular disease, a common disease with a high mortality rate (Kim et al., 2018; Rawshani et al., 2017). Hence, the Jeju black cattle could be a better choice for consumers who consider health a priority.
To compare the nutritional characteristics between Hanwoo, Jeju black cattle, and Australian Wagyu breed, we tested the amino acid composition of meat using GC. The amino acid composition results are presented in Table 2. The amino acid composition was significantly different among breed. Jeju black cattle had higher amounts of alanine than Hanwoo (p<0.05). The amino acid alanine is associated with a sweet taste in meat (Shallenberger and Acree, 1967), so Jeju black cattle beef could be perceived to be sweeter than Hanwoo meat. Glutamic acid was higher in Hanwoo than Jeju black cattle (p<0.01). Glutamic acid is known for its umami taste, the fifth basic taste (Kirimura et al., 1969; Lindemann, 1996; Nelson et al., 2002). Therefore, the consumers might perceive more umami taste in Hanwoo beef.
The amino acids imparting bitter tastes, including valine, leucine, isoleucine, and methionine were higher proportions in Hanwoo than in Jeju black cattle (p<0.05, p<0.001, p<0.001 and p<0.001 each). Compared to the other basic tastes of sweet, sour and salty, the bitter taste remains longer (Kato et al., 1989; Nishimura and Kato, 1988; Solms, 1969). In addition, a previous study showed that people were displeased by a single bitter taste (Drewnowski and Gomez-Carneros, 2000). Therefore, Jeju black cattle could be more preferable than Hanwoo beef.
Jeju black cattle had much more UFA and savory amino acids, including alanine, than Hanwoo and Wagyu breeds. The UFAs, such as oleic acid, provided rich favor. In addition, these UFAs could reduce blood cholesterol. The savory amino acids, such as alanine may affect consumer preference because of the savory taste they impart to beef.
Taken together, our results suggest that Jeju black cattle beef had higher savory flavor and umami taste which affected consumers preference for the meat.