Preliminary microbiological and chemical characterisation of edible goat’s rennet, a unique product of Sardinian food tradition

Figures & data

Table 1. Microbial counts (log cfu gr⁻¹) of nine samples of ‘edible goat rennet’ from three producers (A, B and C).

Microbial groups	A1	A2	A3	B1	B2	B3	C1	C2	C3
Total microbial count	7.44^a ± 0.26	7.47^a ± 0.19	7.60^a ± 0.12	7.17^a ± 0.14	7.35^a ± 0.54	7.36^a ± 0.54	7.65^a ± 0.41	7.75^a ± 0.33	7.63^a ± 0.41
Mesophilic streptococci	7.47^b ± 0.38	7.36^b ± 0.16	7.28^b ± 0.08	6.49^a ± 0.29	6.58^a ± 0.13	6.54^a ± 0.17	7.41^b ± 0.30	7.50^b ± 0.37	7.19^b ± 0.16
Thermophilic streptococci	<10	<10	<10	<10	<10	<10	<10	<10	<10
Mesophilic lactobacilli	6.72^ab ± 0.22	6.61^ab ± 0.37	6.67^ab ± 0.24	6.80^b ± 0.28	6.69^ab ± 0.44	6.71^ab ± 0.38	6.27^a ± 0.13	6.25^a ± 0.20	6.54^ab ± 0.32
Thermophilic lactobacilli	<10	<10	<10	<10	<10	<10	<10	<10	<10
Enterococci	3.44^d ± 0.25	4.50^fg ± 0.36	3.84^de ± 0.06	2.08^c ± 0.07	1.09^a ± 0.15	1.58^b ± 0.05	4.57^g ± 0.05	4.39^fg ± 0.04	4.10^ef ± 0.62
Staphylococci	<10	<10	<10	<10	<10	<10	<10	<10	<10
Yeasts	<10	<10	<10	<10	<10	<10	<10	<10	<10
Total coliforms^h	<3	<3	<3	<3	<3	<3	<3	<3	<3
Faecal coliforms^h	<3	<3	<3	<3	<3	<3	<3	<3	<3
Spores of sulphite-reducing clostridia^h	<3	<3	<3	<3	<3	<3	<3	<3	<3

Average values of three determinations ± SD. Values in the same row with different superscripts are statistical significantly different (p < .05). ^hMPN method.

Table 2. Lactococcus, Lactobacillus and Enterococcus species number isolated from nine edible goat rennet samples from A, B, C farmstead.

	A1	A2	A3	B1	B2	B3	C1	C2	C3
Lactococcus lactis	8	9	9	5	3	4	4	4	3
Lactobacillus casei	4	2	3	4	2	4	5	2	6
Lactobacillus plantarum	1	3	3	5	5	4	5	8	4
Lactobacillus brevis	nd	nd	nd	1	3	2	nd	nd	nd
Enterococcus faecium/durans	10	10	10	6	6	3	10	10	10

nd: not determined.

Table 3. Chemical composition (%) and pH value of edible goat rennet samples from A, B, C farmstead.

	A1	A2	A3	B1	B2	B3	C1	C2	C3
Total solid	47.96^b ± 0.37	60.55^c ± 0.45	46.59^a ± 0.15	65.98^d ± 0.28	77.85^h ± 0.23	61.14^c ± 0.56	70.62^f ± 0.21	66.71^e ± 0.25	72.86^g ± 0.65
Fat	13.64^a ± 0.04	25.18^bc ± 0.09	25.43^c ± 0.39	28.60^e ± 0.16	30.63^fg ± 0.41	24.88^b ± 0.35	30.99^g ± 0.26	27.53^d ± 0.24	30.44^f ± 0.28
Total nitrogen	1.90^a ± 0.13	2.49^bc ± 0.10	1.60^a ± 0.32	2.71^bc ± 0.04	3.52^d ± 0.35	2.38^b ± 0.21	2.77^bc ± 0.41	2.80^c ± 0.10	3.42^d ± 0.23
Proteins	12.15^a ± 0.27	15.87^bc ± 0.27	10.19^a ± 0.40	17.29^bc ± 0.29	22.45^d ± 0.67	15.16^b ± 0.18	17.67^bc ± 0.07	17.88^c ± 0.08	21.83^d ± 0.05
pH	4.90^a ± 0.01	4.74^a ± 0.01	4.87^a ± 0.01	4.91^a ± 0.01	5.01^a ± 0.01	4.88^a ± 0.01	4.78^a ± 0.01	5.00^a ± 0.01	4.80^a ± 0.01

Average values of three determinations ± SD. Values in the same row with different superscripts are statistical significantly different (p < .05).

Table 4. Compositional analysis of free fatty acids (mg Kg⁻¹) of edible goat rennet samples from A, B, C farms.

FFAs	A1	A2	A3	B1	B2	B3	C1	C2	C3
C4:0	90.4^a ± 0.45	96.31^b ± 0.63	90.05^a ± 0.47	96.25^b ± 0.35	102.38^c ± 0.54	96.21^b ± 0.62	102.23^c ± 0.42	90.51^a ± 0.60	102.25^c ± 0.58
C6:0	223.57^a ± 0.78	230.71^c ± 1.40	224.75^a ± 1.81	230.78^c ± 0.81	236.03^d ± 0.72	231.78^c ± 1.87	236.39^d ± 1.38	229.87^b ± 1.72	236.30^d ± 0.85
C8:0	69.57^ab ± 0.42	69.62^ab ± 0.32	70.82^c ± 0.60	70.22^bc ± 0.47	69.38^a ± 0.25	70.43^c ± 0.35	69.47^a ± 0.47	72.35^d ± 0.40	69.38^a ± 0.28
C10:0	243.43^c ± 2.30	237.66^b ± 4.13	232.97^a ± 1.04	249.33^d ± 1.63	235.67^ab ± 1.24	246.69^d ± 1.02	235.66^ab ± 1.24	253.95^e ± 2.28	265.49^f ± 1.50
C12:0	804.68^a ± 3.24	819.74^cd ± 6.94	807.12^a ± 4.25	819.56^cd ± 5.74	826.88^de ± 2.90	817.11^bc ± 2.49	827.43^e ± 2.97	810.50^ab ± 3.27	829.09^e ± 5.96
C14:0	1014.28^c ± 6.50	979.22^b ± 5.38	1015.37^a ± 5.09	976.33^b ± 2.98	943.86^a ± 6.79	978.39^b ± 6.27	943.94^a ± 4.97	1018.53^c ± 9.63	942.80^a ± 3.91
C16:0	1305.94^d ± 5.42	1276.12^b ± 9.60	1314.65^d ± 5.30	1267.70^b ± 7.41	1238.24^a ± 8.67	1272.93^b ± 7.42	1238.25^a ± 8.67	1291.56^c ± 2.58	1234.94^a ± 4.44
C16:1	80.97^d ± 0.49	76.06^b ± 0.49	81.05^d ± 0.77	76.62^bc ± 0.23	71.39^a ± 0.32	77.12^c ± 0.73	71.25^a ± 0.22	83.86^e ± 0.75	71.75^a ± 0.68
C18:0	894.06^e ± 4.02	761.04^b ± 4.45	873.97^d ± 2.20	771.51^c ± 7.30	637.48^a ± 3.73	764.60^bc ± 4.46	638.55^a ± 4.59	900.86^e ± 3.63	636.49^a ± 1.94
C18:1	1812.84^f ± 16.28	1652.61^d ± 5.79	1910.04^g ± 13.73	1606.87^b ± 9.36	1453.38^a ± 6.54	1630.78^c ± 10.83	1454.71^a ± 9.51	1699.85^e ± 5.19	1455.36^a ± 8.85
C18:2	181.04^c ± 0.91	181.18^c ± 1.30	200.29^f ± 1.31	178.31^b ± 0.54	171.49^a ± 0.78	183.93^d ± 1.18	171.43^a ± 1.23	191.22^e ± 1.27	170.99^a ± 0.61
C18:3	170.95^d ± 1.04	149.73^b ± 0.82	173.27^e ± 0.87	151.36^c ± 0.92	127.12^a ± 0.39	151.79^c ± 0.83	127.43^a ± 0.58	179.01^f ± 1.09	127.59^a ± 0.82

Average values of three determinations ± SD. Values in the same row with different superscripts are statistical significantly different (p < .05).