Effect of Fat Content on the Thermal Effusivity of Foods: An Inverse Photopyroelectric Study

Figures & data

Table 1 The content (in grams) of different constituents per 100 g sour cream and mayonnaise

	Samples of sour cream (S)						Mayonnaise (M) samples
Constituents g/100 g	S1	S2	S3	S4	S5	S6	M1	M2	M3	M4	M5	M6
Protein	3	2.8	2.7	2.6	2.48	2.4	0.7	0.74	0.79	0.81	0.85	1
Lactose	3.6	3.47	3.2	3.38	3.16	2.95	–	–	–	–	–	–
Carbohydrate	–	–	–	–	–	–	7	6.39	6.04	5.14	5	3
Fat	12	15.2	20	22.22	28	31.4	27	35	40	53	65	80
Water	81.4	78.53	74.1	71.8	66.36	63.25	31.5	28.8	27.2	26.44	22.65	13.8
Unknown Components	–	–	–	–	–	–	33.8	29.07	25.97	14.61	6.5	2.2

Figure 1 The IPPE sensor.

Figure 2 The experimental arrangement for the assessment of thermal effusivity by the IPPE method.

Figure 3 The amplitude of the IPPE signal obtained from distilled water (□) and the sour cream S1 (♦) plotted versus the square root of the modulation frequency.

Table 2 Experimentally obtained effusivity for sour creams (S) and mayonnaise (M) with a varying fat content

	S1	S2	S3	S4	S5	S6	M1	M2	M3	M4	M5	M6
Effusivity (Ws^1/2m^−2K^−1)	1623 ± 10	1580 ± 14	1521 ± 11	1479 ± 13	1431 ± 12	1407 ± 25	1502 ± 13	1381 ± 19	1314 ± 13	1149 ± 12	822 ± 6	739 ± 3

Table 3 Specific heat, thermal conductivity and density of various food constituents and thermal effusivity values calculated from the literature data

Constituents	Density (kg/m^3)	Specific heat (J/(kgK))	Thermal conductivity (W/(mK))
Protein	2–2,5	170–210	910–950
Carbohydrate	1.6	550–670	1590
Fat	2.93	559	895
Samples of sour cream		Calculated thermal effusivity (Ws^1/2m^−2K^−1)	Difference (%)
S1		1501.5	−7.5
S2		1488.8	−5.8
S3		1472.1	−3.3
S4		1464.2	−1
S5		1444.7	0.095
S6		1433.5	1.9