Classification of entomological origin of honey based on its physicochemical and antioxidant properties

Figures & data

Table 1. Physicochemical properties of various honey samples.

	Bee species/honey types
	Apis dorsata	Apis dorsata	Apis mellifera	Apis cerana	Heterotrigona itama	NA	NA	NA
Parameter	Tualang (N = 2)	Gelam (N = 2)	Pineapple (N = 2)	Borneo (N = 2)	Kelulut (N = 3)	Manuka (N = 1)	Commercial Y (N = 1)	Commercial Z (N = 1)
Moisture content (g/100 g)	26.62 ± 0.50^b	27.41 ± 0.46^b	23.55 ± 0.27^c	21.96 ± 0.67^cd	33.24 ± 2.54^a	19.64 ± 0.27^de	17.98 ± 0.42^e	19.37 ± 0.09^de
Water activity	0.64 ± 0.00^bc	0.67 ± 0.01^b	0.62 ± 0.00^cd	0.60 ± 0.01^d	0.76 ± 0.03^a	0.57 ± 0.00^e	0.54 ± 0.00^e	0.55 ± 0.01^e
Specific gravity	1.39 ± 0.05^a	1.38 ± 0.05^a	1.40 ± 0.05^a	1.41 ± 0.05^a	1.36 ± 0.04^a	1.43 ± 0.05^a	1.44 ± 0.05^a	1.43 ± 0.06^a
Viscosity (Pa·s)	0.76 ± 0.22^e	0.53 ± 0.06^ef	1.52 ± 0.03^d	2.06 ± 0.22^c	0.29 ± 0.18^f	5.43 ± 0.04^b	6.95 ± 0.04^a	5.68 ± 0.04^b
pH	3.74 ± 0.23^b	3.69 ± 0.09^b	3.22 ± 0.10^c	3.73 ± 0.11^b	3.26 ± 0.15^c	3.91 ± 0.00^ab	4.23 ± 0.00^a	3.14 ± 0.00^c
Free acidity (meq/kg)	54.9 ± 7.0^b	54.3 ± 4.4^b	48.6 ± 1.9^b	47.6 ± 0.8^b	136.8 ± 7.6^a	50.0 ± 1.0^b	15.0 ± 1.0^c	11.7 ± 0.6^c
Electrical conductivity (mS/cm)	0.73 ± 0.08^bc	0.96 ± 0.00^ab	0.40 ± 0.00^cd	0.96 ± 0.00^ab	1.08 ± 0.37^a	1.22 ± 0.00^a	0.56 ± 0.00^bcd	0.10 ± 0.00^d
L*	26.52 ± 0.24^bc	26.06 ± 0.11^bcd	27.31 ± 0.91^ab	25.86 ± 0.26^cd	24.90 ± 1.38^de	23.70 ± 0.04^e	29.03 ± 0.01^a	25.94 ± 0.02^bcd
a*	1.42 ± 0.04^a	2.10 ± 0.10^a	2.05 ± 0.70^a	1.45 ± 0.16^a	1.90 ± 0.49^a	0.09 ± 0.02^b	2.02 ± 0.03^a	1.90 ± 0.03^a
b*	2.96 ± 0.11^bc	2.78 ± 0.11^bc	3.59 ± 0.26^b	2.66 ± 0.16^bc	2.52 ± 1.05^c	0.15 ± 0.02^d	7.68 ± 0.07^a	2.64 ± 0.03^bc
Colour intensity (mAU)	475.5 ± 82.4^c	446.5 ± 153.2^c	580.7 ± 48.6^c	376.7 ± 27.4^c	990.3 ± 380.0^b	7296.7 ± 15.3^a	211.3 ± 0.6^c	424.3 ± 1.5^c

NA: not known; N: number of analysed samples from different batches;

Mean ± standard deviation values (n = 3 replicates × N) followed by different superscript letters in each row are significantly different (P < 0.05).

Figure 1. Antioxidant properties of (a) DPPH free radical scavenging activity power (1/IC50); (b) ascorbic acid equivalent antioxidant capacity (AEAC); (c) ferric ion reducing antioxidant power (FRAP); and (d) total phenolic content (TPC) of various honey samples (T: Tualang; G: Gelam; P: Pineapple; B: Borneo; K: Kelulut; M: Manuka; CY: Commercial Y; CZ: Commercial Z). Values presented are mean ± standard error (n = 3 × N) with different letters indicate significant differences (P < 0.05).

Table 2. Pearson correlation coefficients between various properties of honey.

	MC	aw	SG	V	pH	FA	EC	L*	a*	b*	CI	1/IC50	AEAC	FRAP	TPC
MC	1.000
aw	0.982*	1.000
SG	−0.990*	−0.974*	1.000
V	−0.816*	−0.805**	0.848*	1.000
pH	−0.405	−0.418	0.407	0.394	1.000
FA	0.896*	0.922*	−0.855*	−0.644	−0.438	1.000
EC	0.515	0.502	−0.436	−0.349	0.278	0.570	1.000
L*	−0.298	−0.329	0.214	0.211	0.308	−0.515	−0.480	1.000
a*	0.299	0.270	−0.310	−0.275	−0.331	0.138	−0.176	0.247	1.000
b*	−0.264	−0.257	0.211	0.304	0.268	−0.334	−0.492	0.808*	0.378	1.000
CI	−0.179	−0.168	0.252	0.347	0.207	0.039	0.417	−0.521	−0.681	−0.566	1.000
1/IC50	0.061	0.061	0.028	0.223	0.178	0.263	0.619	−0.539	−0.570	−0.588	0.944*	1.000
AEAC	−0.048	−0.049	0.138	0.279	0.230	0.167	0.589	−0.550	−0.594	−0.598	0.968*	0.988*	1.000
FRAP	0.011	0.015	0.074	0.220	0.212	0.212	0.599	−0.535	−0.601	−0.593	0.966*	0.993*	0.994*	1.000
TPC	0.072	0.065	0.005	0.103	0.135	0.225	0.603	−0.548	−0.577	−0.657	0.953*	0.968*	0.968*	0.982*	1.000

MC: moisture content; a_w: water activity; SG: specific gravity; V: viscosity; FA: free acidity; EC: electrical conductivity; CI: colour intensity; 1/IC50: DPPH free radical scavenging activity power; AEAC: Ascorbic acid equivalent antioxidant capacity; FRAP: ferric ion reducing antioxidant power; TPC: total phenolic content.

*P ≤ 0.0005; **P ≤ 0.001.

Figure 2. Dendrogram of hierarchical cluster analysis based on physicochemical and antioxidant properties of various honey samples. The codes of A and B of raw honeys indicate the samples from different batches.

Figure 3. The (a) loading plot for PC2 versus PC1; (b) loading plot for PC3 versus PC2; (c) score plot for PC2 versus PC1; and (d) score plot for PC3 versus PC2 from PCA based on physicochemical and antioxidant properties for honey classification following its entomological origin (I: Heterotrigona itama; II: Apis dorsata and Apis cerana; III: Apis mellifera; IV: Apis cerana). The codes of A and B of raw honeys indicate the samples from different batches.