Development of a Novel Whey Date Beverage Fermented with Kefir Grains Using Response Surface Methodology

Table 5

Analysis of variance and regression analysis.

Source	Sum of squares	DF	Mean squares	F value	Signif. %
pH
Model	0.6427	9	0.0714	25.0873
Residual	0.0256	9	0.0028
Lack of fit	0.0179	5	0.0036	1.8550	28.4
Pure error	0.0077	4	0.0019
Total	0.6684	18
R^2 = 0.962; Adj-R^2 = 0.923
LAB (log10 CFU/mL)
Model	55.3596	9	6.1511	59.5603
Residual	0.9295	9	0.1033
Lack of fit	0.5648	5	0.1130	1.2390	42.9
Pure error	0.3647	4	0.0912
Total	56.2891	18
R^2 = 0.983; Adj-R^2 = 0.967
Yeasts (log10 CFU/mL)
Model	30.7575	9	3.4175	370.6613
Residual	2.3358	9	0.2595
Lack of fit	2.2989	5	0.4598	49.8674
Pure error	0.0369	4	0.0092
Total	33.0932	18
R^2 = 0.929; Adj-R^2 = 0.859
DPPH scavenging activity (%)
Model	288.9329	9	32.1037	529.0648
Residual	17.2440	9	1.9160
Lack of fit	17.0013	5	3.4003	56.0359
Pure error	0.2427	4	0.0607
Total	306.1769	18
R^2 = 0.944; Adj-R^2 = 0.887
Total phenolic content (mg/mL)
Model	4.50380E + 0003	9	5.00422E + 0002	714.8885
Residual	3.82025E + 0001	9	4.24472E + 0000
Lack of fit	3.54025E + 0001	5	7.08050E + 0000	10.1150
Pure error	2.80000E + 0000	4	7.00000E − 0001
Total	4.54200E + 0003	18
R^2 = 0.992; Adj- R^2 = 0.983
Overall acceptability (score)
Model	27.4714	9	3.0524	234.7983
Residual	0.9654	9	0.1073
Lack of fit	0.9134	5	0.1827	14.0530
Pure error	0.0520	4	0.0130
Total	28.4368	18
R^2 = 0.966; Adj-R^2 = 0.932

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