Flavour improvement of reduced-fat peanut butter by addition of a kokumi peptide, ?-glutamyl-valyl-glycine

In this study, first, the sensory attributes of peanut butter were discussed and selected
by expert panellists. Then, panellists rated the differences between reduced- and
full-fat peanut butter to establish how increased fat affected the sensory attributes
of peanut butter. Finally, the same evaluation was conducted comparing reduced-fat
peanut butter and that with kokumi peptide, ?-Glu-Val-Gly.

Sensory attributes

During the group discussion, panellists listed up the words, selected the attributes
and made a consensus of the sensation which the attribute expressed. Finally, the
panellists developed ten attributes: peanut flavour, saltiness, sweetness, bitterness,
thick flavour (thickness of taste; the enhancement of taste intensity with maintaining
the balance of taste), aftertaste (the total aftertaste intensity after 5 s of all
flavour notes within the sample), continuity of taste (the taste intensity at ~20 s),
smoothness, and oiliness.

Comparison between reduced-fat sample and full-fat model of peanut butter

Comparison between reduced-fat peanut butter and full-fat model peanut butter is shown
in Table 1. The full-fat model peanut butter had higher scores for peanut flavour, thick flavour,
aftertaste, continuity of taste, and oiliness than for low-fat peanut butter. No significant
difference in saltiness, sweetness, bitterness, smoothness, and viscous sensation
was observed between the low-fat sample and full-fat model. We consider that the fat
enhanced the above sensory character in peanut butter. In other words, we considered
that peanut flavour, thick flavour, aftertaste, continuity of taste, and oiliness
were the sensory functions of fat in peanut butter.

Table 1. Result of the comparison test between low-fat peanut butter and full-fat model peanut
butter

Effect of addition of ?-Glu-Val-Gly in reduced-fat peanut butter

To clarify the effect of ?-Glu-Val-Gly on the sensory character of reduced-fat peanut
butter, reduced-fat peanut butter with 40 ppm ?-Glu-Val-Gly was evaluated for the
attributes, peanut flavour, thick flavour, aftertaste, continuity of taste, and oiliness.
The results of the sensory evaluation are shown in Table 2. Addition of ?-Glu-Val-Gly significantly enhanced the intensities of thick flavour,
aftertaste, and oiliness. These results demonstrated that the addition of ?-Glu-Val-Gly
increased some sensations that were lacking in the reduced-fat peanut butter, suggesting
that addition of the peptide can be used for flavour improvement in reduced-fat peanut
butter.

Table 2. Effect of ?-Glu-Val-Gly on the low-fat peanut butter

The previous studies described that the several reduced-fat foods and low-fat foods
lacked the sensations related to ‘thick flavour’, ‘aftertaste’ and ‘oiliness’. For
example, it has been previously reported that the low-fat sausage has lower juiciness
and aftertaste intensity 10] and that low-fat yogurt has lower creaminess 11] than full-fat products. In addition, it has been previously reported that reduced-fat
ice cream indicated lower scores of texture-related attributes such as thickness,
smoothness, creaminess, mouth coating than those of full-fat products 12]. Therefore, it is considered that the addition of ?-Glu-Val-Gly can be used to improve
the flavour of other reduced-fat foods. In order to clarify this possibility, it is
necessary to conduct a preference test using a consumer panel, and this test is now
in progress in our laboratory. The effect of ?-Glu-Val-Gly on other reduced-fat foods
is also now under investigation in our laboratory.