This study is the first in the literature to show a significant relationship between fatty acids and butter color and to say that fatty acids can affect the color of butter.

Halil Ibrahim AKGUL¹, Mustafa SENGUL²

¹Bayburt University, Food Engineering Department, Bayburt, Turkey

²Ataturk University, Food Engineering Department, Erzurum, Turkey

3rd International Conference on Advanced Engineering Technologies, 19-21 September 2019

Abstract

In this study, physicochemical properties and fatty acid profile of 30 butter samples were studied and the relationship of these parameters with the color of butter was investigated. Statistically significant correlations were found between the color of butter and dry matter, fat, salt ratio, peroxide value, polenske value and C_6:0, C_8:0, C_10:0, C_14:0, C_14:1, C_18:0, C_18:1 and C_18:2 fatty acids.

Keywords; Butter color, fatty acid, statistics

Introduction

The natural yellow color of butter mainly results from carotene dissolved in the fat, which originates from the feed and together with the characteristic microstructure of well-worked butter [1]. The yellow color of butter carries consumer perceptions of “fresh grass-feeding” [2, 3].

Previous studies [1, 4-9] have suggested that many factors such as vitamin A, vitamin E content, season, processing, storage time and conditions can affect the color of butter. Although there are not enough studies color of butter in the literature, this study examined whether a relationship between some other properties of butter and color. Thus, the usability of color as a measure for different parameters of butter was questioned.

Material and method

Material

Thirty butter samples were collected from town regions of Trabzon province, Turkey. Samples were immediately transported in the cold chain to the laboratory at Food Engineering Department at Ataturk University. Butter samples were stored in sterile closed plastic containers at 4°C until further analysis. Some sample was taken from each butter sample and stored at -20^oC until analysis to determine butter fatty acid composition.

Methods

Dry matter, fat and salt contents, melting point, peroxide value, iodine value, saponification value, Reichert-Meissl number and polenske value were determined according to the methods of  Kurt et al. [10]. pH values of the samples were measured using a digital pH meter (pH 211, Hanna Instruments, Italy) according to the method of Kosikowski [11]. Titratable acidity (lactic acid %) was determined according to the method of Metin [12]. The butter samples’ water activity (a_w) was measured using LabMaster-a_w (Novasina AG, Switzerland).

Colour measurement of the butter samples was performed using a Minolta Colorimeter using the Hunter scale according to the method of Elgün et al. [13].

Fatty acid methyl esters (FAME) were prepared as described by Erkaya et al. [14] and Metcalfe and Schmitz [15]. 50 mg of each butter sample was weighed and placed into glass tubes. 1,5 mL of NaOH (2M) solution was added and the tubes were filled with nitrogen gas. The Tubes were heated at 80^oC for one h. 2 mL of BF3 (%25, in methanol w/v) solution was added to the tubes after cooling and heated again at 80^oC for 30 min. 1 mL of hexane and 1 mL ultra distilled water was added to the tubes and vortexed. Upper layers were transferred to GC vials. These esters were injected into a GC system (Agilent 6890N, HP, USA) equipped with a flame ionization detector (Agilent Tech. Inc.) at 200^oC and DB-23 column (60 m x 0.25 mm x 0.25 mm).

Helium was used as the carrier gas and C_19:0 was used as the internal standard.

Correlation analyses were performed with SPSS statistical software program version 17.0 (SPSS Inc., Chicago, IL, USA).

Results

The statistical relationship between some properties of butter and color values is given in Table 1. Pearson correlation coefficients between color values (L*, a*,b*) and different properties of butter revealed some statistically significant correlations. 

Statistically significant correlations were found between the color of butter and dry matter (L* P<0.01, a* P<0.05), fat (L* P<0.05, a* P<0.05) and salt ratio (L* P<0.01, a* P<0.01), peroxide value (L* P<0.05), melting point (L* P<0.01, a* P<0.01) and polenske number (L* P<0.05, b* P<0.05). 

The statistical relationship between fatty acids of butter and color values is given in Table 2. Statistically significant relationships were found between C_6:0 (P<0,01), C_8:0 (P<0,05) and C_10:0 (P<0,05) fatty acids and L* value in accordance with the statistical relationship between the Polenske number and L* value.

On the other hand, C_18:0, C_18:1 and C_18:2 fatty acids were also statistically significant with L* and a* values. As a matter of fact, Gonzalez et al. [16] stated that the butter sample having a high C_18:1 value had a higher L* value than the control butter sample.

O’Callaghan et al. [3] mentioned that no significant difference was observed in the butter’s L* and a* values at different cow feeding systems and different trans-β-carotene content; however, significant differences were recorded for the b* value of the butter. In this study, we found significant relationships between fatty acids and L* and a* values.

Conclusion

In this study, as expected, dry matter, the fat, salt content of butter and peroxide number were found to be statistically related to color values. Interestingly, the number of polenske and fatty acids was also significantly correlated with the color values of butter. These results show that fatty acids can affect the color of butter. However, further research is needed.

References

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You can cite this study as; Akgul, HI and Sengul, M 2019. “Relationship between some parameters and color in butter.” 3rd International Conference on Advanced Engineering Technologies (ICADET 2019). Proceedings book p.p. 1770 – 1773. (see the conference website)