Table 2.

Means of main minerals, organic acids, sugars, physico-chemical characteristics and microbial counts in maple sap collected with control vacuum level (20 InHg) and high-vacuum level (28 InHg) in the tubing system with respective P-values.

Analysis	Control - 20 InHg		High vacuum - 28 InHg
	Meana	SDb	Mean	SD	p value*
Minerals (μg/g)
Potassium	69.55	6.70	72.99	7.49	0.053
Calcium	117.12	24.72	112.94	25.55	0.38
Magnesium	9.64	1.74	9.79	1.88	0.83
Sodium	0.03	0.04	0.03	0.03	0.69
Zinc	0.28	0.05	0.28	0.05	0.92
Manganese	2.28	0.50	2.39	0.59	0.44
Organic Acids (μg/g)
Oxalic	0.54	0.41	0.33	0.14	0.0495∗
Quinic	45.44	48.47	34.41	45.62	0.15
Pyruvic	5.96	5.60	5.38	5.89	0.41
Malic	274.18	114.86	300.92	87.29	0.45
Fumaric	6.55	5.59	6.94	5.72	1.00
Succinic	52.82	80.70	52.43	82.34	0.76
Sugars (%)
Sucrose	1.98	0.42	1.96	0.36	0.50
Glucose	0.03	0.03	0.01	0.01	0.005∗∗
Fructose	0.04	0.07	0.01	0.01	0.02∗
Physico-chemical
pH	7.08	0.83	7.17	0.88	0.64
TSS (Brix)c	2.16	0.22	2.06	0.30	0.15
Conductivity (uS/cm)	585.21	84.44	578.94	87.51	0.77
Microbial counts (log CFU/ml)
Bacteria	5.73	1.09	5.46	1.03	0.26
Fungi	5.07	1.56	4.49	1.38	0.07

*One star denotes significance at the 0.05 level, and two stars denotes significance at the 0.01 level.

^aN = 33.

^bStandard deviation.

^cTotal Soluble Solids.