Written by: Alla Katsnelson, Ph.D | Issue # 113 | 2023
- Researchers developed a list of 53 terms describing the flavor properties of human milk.
- The fat content of human milk determines key features of its taste.
- Understanding the flavor components of human milk can help develop infant formula that is close in taste to human milk.
Scientists know little about the flavor of human milk, but they do know that flavor plays a large role in breastfeeding [1]. In a new study, researchers have constructed the first-ever flavor wheel for human milk—a tool that can be used to objectively describe and quantify the substance’s flavor and sensory properties [2].
“Flavor is an important factor influencing infants’ food choices,” said Yajun Xu, Vice Dean of the School of Public Health at Peking University in China and one of the study’s lead authors, in an email to SPLASH! The results, he added, provide “a solid and essential understructure for flavor research … [and] will enable us to further decode the substantial flavor substances not only in human milk but also in infant formula.”
Xu and his colleagues obtained a milk sample from 18 mothers—six from each of three provinces in eastern China: Beijing, Jiangsu and Anhui. They then assembled a panel of 12 sensory evaluators with experience evaluating dairy products to assess the milk samples in a laboratory at Beijing Technology and Business University.
To build the flavor wheel, panelists first generated a list of 84 descriptors of human milk from six randomly selected samples. The researchers then worked with panelists to standardize the terms by applying a widely-accepted method called “international organization standardization of sensory descriptors selection.” They settled on 53 terms: 30 descriptors of aroma, 14 descriptors of flavor, and nine descriptors of mouthfeel. These terms were organized into 18 groupings, each of which were subsets of three main sensory modalities—aroma, flavor, and mouthfeel.
Next, the researchers paired down the list of descriptors from the flavor wheel by assessing which ones the panelists found to be most intensely present in the samples they had initially screened. After removing some descriptors and combining others, they ended on 15 terms that described the flavor variability in their samples. These terms were fishy, dairy-fat, metallic/iron, cooked, flour, dairy-sweet, and grassy/green for aroma; sweet, umami, creamy, fishy, and boiled milk for taste; and silky, fattiness, and mouthfulness, which the researchers defined as “the feel of coating, long-lasting, thickness,” in the paper as for mouthfeel.
Finally, the team asked panelists to analyze the full set of 18 collected samples based on the 15 descriptors. The most prominent sensory attributes that the panelists identified were dairy-fat and dairy-sweet for aroma, sweet and creamy for flavor, and silky for mouthfeel. But the samples tended to have highly different scores for each descriptor. To explore relationships within those differences, the researchers grouped the samples in multiple ways, such as by region, by lactation time, and by fat content. “Surprisingly, the samples with a similar fat content exhibited more analogous sensory profiles,” Xu said in an email. This suggests that fat content is a key determinant of flavor for human milk, he said.
The researchers note that in their study, the tasters were adults, and not infants—and it’s unknown whether adults and infants experience flavor the same way. Nonetheless, the work makes it possible to home in on the specific flavor molecules responsible for taste differences, the researchers say. Another key goal is to reduce or eliminate flavor differences between human milk and infant formula, which have been identified in earlier work. Producing formula that more closely mimics human milk’s flavor may prove helpful for infants who struggle with breastfeeding.
References
- Raimbault C, Saliba E, Porter RH. The Effect of the Odour of Mother’s Milk on Breastfeeding Behaviour of Premature Neonates. Acta Paediatr. 2007, 96, 368–371.
- Yu M, Zheng C, Xie O , Tang Y, Wang Y, Wang B, Song H, Zhou Y, Xu Y, Yang R. Flavor Wheel Construction and Sensory Profile Description of Human Milk. Nutrients. Dec 19;14(24):5387.
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