الفهرس 
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Abstract
A total of 100 random samples from Mish, Domiati, Cheddar and Rommano cheeses (25 of each), were collected from different sources and localities in Beni-Suef city to determine the level of histamine in cheese by using RIDASCREEN® HISTAMIN.
Also, four batch of Egyptian Domiati cheese were manufactured, the first batch (T1) was maintained without any further inoculation (negative control). The second batch (T2) was separately inoculated with L. hilggardii. The third batch (T3) inoculated with L. hilggardii and Lb. acidophilus. The last batch (T4) inoculated with L. hilggardii and B. bifidum. Four batches divided into two parts one stored at 4°C and the other stored at 25°C for period for 4 month.
All manufactured samples were examined to detect the level of histamine at zero day, one, two, three and four month and for show the viability of microbes at zero, one, two, three, four months.
The statistical analytical results showed that:-
Part I : Histamine levels in cheese samples:-
All examined Mish cheese samples 25 (100%) contain histamine level from 7.32 to 250 mg/kg with a mean of (114.16 ± 2.95) mg/kg. Statistical analysis showed that 22(88%) out of tested samples within permissible limit (200mg/kg) while 3(12%) out of Mish samples above permissible limit according to Egyptian Standard (2008).
Statistical analysis showed that 16 (64%) out of 25 Domiati cheese samples contained histamine (38.24 ± 1.85) with in permissible limit (200mg/kg) according to Egyptian Standard (2008).
All examined Cheddar cheese samples (25) about (14) sample which represent 56% contain histamine. Histamine level in Cheddar cheese samples ranged from 5.15 to 37.8 mg/kg with a mean (9.96 ± 0.46) mg/kg. Statistical analysis showed that 14 (56%) out of 25 Cheddar samples contained histamine with in permissible limit (200mg/kg) according to Egyptian Standard (2008).
All examined Rommano cheese samples (25) which represent 100% contain histamine .Histamine level in Rommano cheese samples ranged from 16 to 417.5 mg/kg with a mean (126.77 ± 4.69) mg/kg. Statistical analysis showed that 20 (80%) out of 25 Rommano samples contained histamine with in permissible limit (200mg/kg) according to Egyptian Standard (2008), about 5 (20%) out of 25 Rommano sample contain histamine above permissible limit.
Part II: Impact of probiotic bacteria on the growth and survival of L.hilgardi microorganism in vitro inoculated during damitai cheese manufacture and storage for 120 day at 4°C and 25°C:
The first point was detection of the effect of storage period and temperature on the level of histamine in Egyptian manufactured domiati cheese.
The level of histamine in T1, T2, T3 and T4 batches increase by increase of storage period and increase of temperature of storage, with the exception of the final month, found level of histamine increase in first batch (control) stored at 25°C from below the limit of detection, 2.5, 18 and 19.7 at zero, one, two and three month respectively, higher than that storage at same period at 4°C where level of histamine were below the limit of detection, 2.5, 14.9 and 18.2 at zero, one, two and three month, with the exception of the final four month the histamine level decrease to 14.7 and 7 mg/kg at 4°C and 25°C respectively.
The level of histamine in second batch which contain (L. hilgardii) and stored at 25°C ranged from below the limit of detection, 2.9, 2 and 22 at zero, one, two and three month respectively, higher than that storage at same period at 4°C where level of histamine were below the limit of detection, 2.5, 18.5 and 19.4, with the exception of the final four month the histamine level decrease to 13.9 and 13.1 mg/kg at 4°C and 25°C respectively.
The level of histamine in third batch which contain (L. hilgardii + L. acidophilus) and stored at 25°C ranged from below the limit of detection, 2.5, 17.8 and 19 at zero, one, two and three month respectively, higher than that storage at same period at 4°Cwhere level of histamine were below the limit of detection, 2.5, 9.5 and 18.5, with the exception of the final four month the histamine level decrease to 15 and 9.2 mg/kg at 4°C and 25°C respectively.
The level of histamine in fourth batch which contain (L. hilgardii + B. bifidum) and stored at 25°C ranged from below the limit of detection, 2.5, 19.3 and 20 at zero, one, two and three month respectively, higher than that storage at same period at 4°C where level of histamine were below the limit of detection, 2.5, 14.4 and 18.6, with the exception of the final four month the histamine level decrease to 11.7 and 11.6 mg/kg at 4°C and 25°C respectively.
The second point was the evaluation of impact of probiotic strains as Lactobacillus acidophilus and B.bifidum on the growth and survival of Lactbacillus hilgardii and on the level of histamine.
Batch T1 L.hilgardii ND in 4 months of ripening at 4°C, while in group T2 we found that number of L.hilgardii decrease during the storage period reached levels of 7.5×109, 6.8×102 and ND till the end of period of storage at zero, one, two, three and four month respectively, in T3 group we found that number of L. hilgardii decrease during the storage period reached levels of 2×109, 5.5×102 and ND till the end of period of storage, while we found that number of Lb. acidophilus decrease during the storage period reached levels of 1.2×1010, 5×103, 40, ND till the end of period of storage at zero, one, two, three and four month respectively, in T4 group we found that number of L. hilgardii decrease during the storage period reached levels of 4.2×109, 9×102 and ND while we found number of B.bifidum reached levels of 1.2×1010, 6×104, 30 and ND till the end of period of storage at zero, one, two, three and four month respectively.
In the batches were stored at 25 °C we found that control batch T1 L. hilgardii ND till the end of 4 months of ripening, while in group T2 we found that number of L. hilgardii decrease during the storage period reached levels of 9×109, 1×103 and ND till the end of period of storage at zero, one, two, three and four month respectively, in T3 group we found that number of L. hilgardii decrease during the storage period reached levels of 1×109, 9×102 and ND cfu/g till the end of period of storage, while we found that number of Lb. acidophilus decrease during the storage period reached levels of 5×109, 2.4×103 and ND cfu/g till the end of period of storage at zero, one, two, three and four month respectively, in T4 group we found found number of L.hilgardii decrease during the storage period reached levels of 6×1010, 8.7×102 and ND cfu/g, while we found that number of B.bifidum reached levels of 1×1010, 4×103 and ND cfu/g till the end of period of storage at zero, one, two, three and four month respectively.
It is evident that there is no significant effect of probiotics on histamine production and control because P value > 0.05, L. hilgardii is one of the histamine producing microorganism.