Fate of pyrrolizidine alkaloids during processing of milk of cows treated with ragwort

Figures & data

Figure 1. Schedule of milk processing using the pilot scale facilities at NIZO Food Research.

Table 1. MS/MS conditions used for the analysis of pyrrolizidine alkaloids in common ragwort (Jacobaea vulgaris) and narrow-leaved ragwort (Senecio inaequidens).

Compound	Abbrev.	Precursor ion (m/z)	Product ions (m/z)	Collision energy (eV)	Retention time (min)	Standard for quantification
Heliotrine (IS)	He	314.2	138.0	25	8.15
Senecionine	Sn	336.2	94.0; 120.0	40; 30	9.63	Sn
Senecionine N-oxide	SnNO	352.2	94.0; 120.0	40; 30	6.76	SnNO
Integerrimine	Ir	336.2	94.0; 120.0	40; 30	9.43	Ir
Integerrimine N-oxide	IrNO	352.2	94.0; 120.0	40; 30	6.63	IrNO
Senecivernine	Sv	336.2	94.0; 120.0	40; 30	9.80	Sv
Senecivernine N-oxide	SvNO	352.2	94.0; 120.0	40; 30	6.70	SvNO
Retrorsine	Rt	352.2	94.0; 120.0	40; 30	8.27	Rt
Retrorsine N-oxide	RtNO	368.2	94.0; 120.0	40; 30	5.81	RtNO
Seneciphylline	Sp	334.2	94.0; 120.0	40; 30	8.89	Sp
Seneciphylline N-oxide	SpNO	350.2	94.0; 138.0	40; 30	6.15	SpNO
Riddelliine	Rd	350.2	94.0; 138.0	40; 30	7.67	Rd
Riddelliine N-oxide	RdNO	366.2	94.0; 118.0	40; 30	5.28	RdNO
Jacobine	Jb	352.2	120.0; 155.0	30; 30	7.62	Jb
Jacobine N-oxide	JbNO	368.2	120.0; 296.0	30; 25	5.27	JbNO
Jacoline	Jl	370.2	94.0; 138.0	40; 30	5.91	Jl
Jacoline N-oxide	JlNO	386.2	94.0; 120.0	40; 30	4.17	JbNO
Jaconine	Jn	388.2	94.0; 120.0	40; 30	8.50	Jb
Jacozine	Jz	350.2	94.0; 138.0	40; 30	6.99	Jb
Dehydrojacoline	DHJl	368.2	94.0; 120.0	40; 30	5.42	Jl
Hydroxyjacobine	HOJb	368.2	120.0; 296.0	30; 25	6.53	Jl
Erucifoline	Er	350.2	94.0; 120.0	40; 30	7.30	Er
Erucifoline N-oxide	ErNO	366.2	94.0; 118.0	40; 30	4.63	ErNO
Senkirkine	Sk	366.2	122.0; 168.0	30; 25	7.08	Sk
Otosenine	Ot	382.2	122.0; 168.0	30; 25	5.39	Ot
Onetine	On	400.2	122.0; 168.0	30; 30	4.16	Ot
Desacetyldoronine	Dd	418.2	122.0; 168.0	30; 30	6.04	Ot
Florosenine	Fs	424.2	122.0; 168.0	35; 30	8.11	Fs
Floridanine	Fd	442.2	122.0; 168.0	35; 30	6.58	Fs
Doronine	Do	460.2	122.0; 168.0	35; 30	8.77	Fs

The standard that has been used for quantification of the individual compounds is indicated. Cone voltage is 40 V for all compounds.

Table 2. Pyrrolizidine alkaloids in samples of processed milk (µg L⁻¹ and for cheese in µg kg⁻¹)^a.

	Pre-treatment			Heat treatment			Yoghurt		Cheese
Compound	[1]^b	[2]	[3]	[4]	[5]	[6]	[7]	[8]	[9]	[10]	[11]	[12]	[13]	[14]	[15]
Retrorsine^c	0.32	0.31	0.23	0.31	0.40	0.33	0.37	0.35	0.34	0.20	0.29	0.37	0.34	0.39	0.37
Jacobine^c	0.73	0.81	0.51	0.75	0.81	0.78	0.73	0.62	0.86	0.75	0.61	0.92	0.63	0.91	0.80
Jacobine N-oxide^d	0.19	0.18	0.13	0.22	0.22	0.21	0.25	0.21	0.26	0.14	0.11	0.31	<0.05	<0.05	<0.05
Jacoline^c	10.0	11.6	6.5	10.3	11.5	11.7	10.1	6.9	13.3	10.4	7.9	10.4	8.6	8.2	6.4
Jacozinec^c, e	0.16	0.12	0.10	0.19	0.16	0.18	0.15	0.09	0.21	0.09	0.05	0.07	0.09	<0.05	<0.05
Dehydrojacoline^c, e	0.61	0.80	0.50	0.70	0.79	0.68	0.60	0.57	0.76	0.12	0.11	0.26	0.10	0.20	0.10
Hydroxyjacobine^c, e	0.14	0.11	0.06	0.13	0.14	0.15	0.15	0.09	0.17	0.07	0.06	<0.05	<0.05	<0.05	<0.05
Erucifoline ^c	0.10	0.11	0.06	0.10	0.16	0.12	0.10	0.11	0.14	0.10	0.10	0.14	0.12	<0.05	<0.05
Senkirkine^f	0.23	0.26	0.15	0.23	0.23	0.26	0.23	0.20	0.26	0.25	0.19	0.32	0.18	0.20	0.13
Otosenine^f	0.73	0.91	0.52	0.87	0.83	0.67	0.78	0.64	0.75	0.80	0.59	0.43	0.39	0.38	0.32
Florosenine^f	0.40	0.46	0.29	0.45	0.42	0.39	0.37	0.34	0.46	0.43	0.35	0.31	0.25	0.25	0.20
∑ retronecine bases^g	12.0	13.9	8.0	12.5	14.0	13.9	12.2	8.7	15.8	11.7	9.1	12.0	9.9	9.7	7.7
∑ retronecine N-oxides^g	0.19	0.18	0.13	0.22	0.22	0.21	0.25	0.21	0.26	0.14	0.11	0.31	<0.05	<0.05	<0.05
∑ otonecines^g	1.36	1.63	0.96	1.55	1.48	1.32	1.38	1.18	1.47	1.48	1.13	1.06	0.82	0.83	0.65
∑ PAs^g	13.6	15.7	9.1	14.3	15.7	15.5	13.8	10.1	17.5	13.4	10.4	13.4	10.7	10.5	8.3

^aOnly PAs detected in the milk above the LOQ (0.1 µg L⁻¹) are included.

^b[1] thermised milk, [2] Skimmed milk, [3] Cream, [4] Standardised semi-skimmed milk, [5] Pasteurised semi-skimmed milk, [6] UHT sterilised semi-skimmed milk, [7] Yoghurt milk, [8] Yoghurt, [9] Cheese milk, [10] First whey, [11] Second whey, [12] Cheese t = 0 weeks, [13] Cheese t = 2 weeks, [14] Cheese t = 4 weeks, [14] Cheese t = 6 weeks.

^cRetronecine base.

^dRetronecine N-oxide.

^eTentative identification based on molecular weight, mass fragmentation spectrum, and retention time.

^fOtonecine base.

^g∑ sum of retronecine bases, retronecine N-oxides, otonecines, or all PAs measured.

Figure 2. Relative composition of the major PAs present in milk, yoghurt, and cheese products. Sample numbers are explained in Figure 1.

Table 3. Pyrrolizidine alkaloids in cheese milk and subsequently produced whey and fresh cheese (µg L⁻¹ and for cheese in µg kg⁻¹).

	No.	Sample	kg or L	∑PAs µg kg^−1 or L^−1 measured	∑PAs µg
Before treatment	[9]	Cheese milk	10^a	17.5	175
After treatment	[10]	First whey	4^a	13.4	136
	[11]	Second whey	~8^a, b	10.4
	[12]	Cheese	1.1^a	13.4	15

^aVolume at start: 10 L; total volume after treatment: 13.1 kg (4 L first whey, 8 L second whey, and 1.1 kg of cheese).

^bVolume of second whey was not measured, but was estimated at 8 L. Second whey is therefore composed of 5.9 L whey and 2.1 L wash water.