Broilers fed an astaxanthin rich yeast diet produce a better quality meat, say Japanese researchers

The researchers, writing in the Animal Science Journal​, note how supplementing the diet of broiler chickens with a yeast, Phaffia rhodozyma​, containing a high level of astaxanthin yields a breast meat with “significantly improved”​ sensory attributes for tenderness, juiciness, first bite and fibrousness.

“Breast meat is the driest part of edible chicken meat. After cooking, juiciness increased compared with the control group, a very significant point for improving the eating quality of meat. ​

Our results indicate that ​Phaffia rhodozyma​ yeast plays an important role in improving meat texture,”​ said the authors, led by Shinobu Fujimura of the Graduate School of Science and Technology at Niigata University.

They said this study is the first one to show the impact of the inclusion of an astaxanthin-rich yeast in broiler diets on meat quality.

Free radical scavenging ​

Astaxanthin (Ax) occurs naturally in micro algae, yeast, fish and most crustaceans.

A fat-soluble red-colored carotenoid, Ax has proven to be a free radical scavenger and has activity approximately 10 times stronger than that of other carotenoids and 100 times greater than that of α-​tocopherol for singlet oxygen quenching, said the authors.

While the red pigmented yeast Phaffia rhodozyma​ has been used as a dietary source of astaxanthin to improve the pigmentation of broiler meat and egg yolk, almost no studies, apart from meat color improvement, have investigated its use in connection with meat quality, said the Japanese scientists.

Meat quality can be controlled through animal genetics, processing techniques or through nutrition with amino acids, vitamins, minerals and antioxidants playing a significant role in this regard, said the team

And in a bid to evaluate the effect of dietary supplementation with Ax-rich yeast, Phaffia rhodozyma,​ on the meat quality of broiler chickens, the researchers carried out a study on young broiler chickens.

The study ​

One-day-old female Ross strain broilers were purchased from a commercial hatchery. For the first 14 days, the broilers were housed and kept warm in a brooder and fed a commercial starter diet based on corn and soybean meal.

At 14 days of age, they were separated into individual cages and fed on the experimental diets. Feed and water were provided ad libitum​, said the researchers.

The 14-day-old broilers were allocated to three groups for a period of 28 days: a control group involving broilers fed an Ax-free diet; Ax 10 group, broilers fed a diet containing 10 mg/kg Ax; and Ax 20 group, broilers fed a diet containing 20 mg/kg Ax.

There were 12 birds in each group

Findings​

The results revealed that the Ax 20 group significantly increased these sensory attributes of meat texture compared with the control group.

The researchers concluded:

“The main components of muscle considered to affect meat tenderness are myofibrillar protein, muscle cytoskeleton, and intramuscular connective tissue (Harris 1976, Silva ​et al​.1993) and also intra-fiber water (Currie & Wolfe 1980). ​

When myofibrillar protein is oxidized, the oxidation process promotes the aggregation and cross-linkage of protein, so meat becomes tough (Lonergan ​et al​. 2010 Estévez 2011​). ​

For this reason, we suggest that Ax may prevent myofibrillar proteins from oxidizing.”​

Amino acid impact on taste ​

The authors also found that after 120 hours aging, the content of several free amino acids, and the total free amino acid contents of meat samples from the Ax 20 group were significantly higher than the control group.

They said free amino acids, especially glutamic acid can influence the taste of meat and the study’s results suggest that Phaffia​ yeast could improve broiler meat taste during storage..

“This is the first demonstration that Ax-rich yeast can increase the content of free amino acids during the aging of broiler chicken meat and this increase is more effective in diets containing a higher concentration of Ax,”​ said the Japanese scientists.

Publication​: Animal Science Journal ​
Title:​ Effect of dietary astaxanthin rich yeast, Phaffia rhodozyma, on meat quality of broiler chickens​
Article first published online​: 19 May 2014, DOI: 10.1111/asj.12221
Authors​: G Perenlei, H Tojo, T Okada, M Kubota, M, Kadowaki, S Fujimura