scholarly journals Use of natural plant extracts as a novel microbiological quality indicator in raw milk: An alternative for resazurin dye reduction method

LWT ◽  
2021 ◽  
Vol 144 ◽  
pp. 111221
Author(s):  
Ranga Madushan ◽  
Janak K. Vidanarachchi ◽  
P.H.P. Prasanna ◽  
Shanika Werellagama ◽  
Hasitha Priyashantha

Domiati cheese is the most popular brand of cheese ripened in brine in the Middle East in terms of consumed quantities. This study was performed to investigate the impact of the microbiological quality of the used raw materials, the applied traditional processing techniques and ripening period on the quality and safety of the produced cheese. Three hundred random composite samples were collected from three factories at Fayoum Governorate, Egypt. Collected samples represent twenty-five each of: raw milk, table salt, calf rennet, microbial rennet, water, environmental air, whey, fresh cheese, ripened cheese & swabs from: worker hands; cheese molds and utensils; tanks. All samples were examined microbiologically for Standard Plate Count (SPC), coliforms count, Staphylococcus aureus (S. aureus) count, total yeast & mould count, presence of E. coli, Salmonellae and Listeria monocytogenes (L. monocytogenes). The mean value of SPC, coliforms, S. aureus and total yeast & mould counts ranged from (79×102 CFU/m3 for air to 13×108 CFU/g for fresh cheese), (7×102 MPN/ cm2 for tank swabs to 80×106 MPN/ml for raw milk), (9×102 CFU/g for salt to 69×106 CFU/g for fresh cheese) and (2×102 CFU/cm2 for hand swabs to 60×104 CFU/g for fresh cheese), respectively. Whereas, E. coli, Salmonella and L. monocytogenes failed to be detected in all examined samples. There were significant differences in all determined microbiological parameters (p ≤0.05) between fresh and ripened cheese which may be attributed to different adverse conditions such as water activity, pH, salt content and temperature carried out to improve the quality of the product.


2012 ◽  
Vol 16 (3) ◽  
pp. 269-297 ◽  
Author(s):  
Usune Etxeberria ◽  
Ana Laura de la Garza ◽  
Javier Campión ◽  
J Alfredo Martínez ◽  
Fermín I Milagro

2015 ◽  
Vol 26 (1) ◽  
pp. 5-15
Author(s):  
E. Kuta ◽  
C. Ryka

The aim of the present paper Was to test the value of various plant extracts (yeast barm, mature walnut embryos, coconut meal, young spinach leaves and tomato juice) used as the complementary elements of White's mineral nutrient for the culture <i>in vitro</i> of generative apices of winter wheat, rape and wetch. The results showed that the generative apices of investigated planits had various nutritive requirements which point to the necessity of a careful selection of a specific nutrient for particular plant material.


2008 ◽  
Vol 71 (8) ◽  
pp. 1580-1589 ◽  
Author(s):  
DENNIS J. D'AMICO ◽  
ERROL GROVES ◽  
CATHERINE W. DONNELLY

Overall milk quality and prevalence of four target pathogens in raw milk destined for farmstead cheesemaking was examined. Raw milk samples were collected weekly from June to September 2006 from 11 farmstead cheese operations manufacturing raw milk cheese from cow's, goat's, and sheep's milk. Samples were screened for Listeria monocytogenes, Staphylococcus aureus, Salmonella, and Escherichia coli O157:H7 both quantitatively (direct plating) and qualitatively (PCR). Overall, 96.8% of samples had standard plate counts of &lt;100,000 CFU/ml, 42.7% of which were &lt;1,000 CFU/ml. Although no federal standards exist for coliforms in raw milk, 61% of samples tested conformed to pasteurized milk standards under the U.S. Pasteurized Milk Ordinance (PMO) at &lt;10 CFU/ml. All cow and sheep milk samples and 93.8% of goat milk samples were within the limits dictated by the PMO for somatic cell counts. Of the 11 farms, 8 (73%) produced samples that were positive for S. aureus, which was detected in 34.6% (46 of 133) of milk samples. L. monocytogenes was isolated from three milk samples (2.3%), two of which were from the same farm. E. coli O157:H7 was recovered from one sample of goat's milk for an overall incidence of 0.75%. Salmonella was not recovered from any of the 133 samples. The findings of this study suggest that most raw milk intended for farmstead cheesemaking is of high microbiological quality with a low incidence of pathogens. These data will help inform risk assessments associated with the microbiological safety of farmstead cheeses, particularly those manufactured from raw milk.


2019 ◽  
Vol 9 (13) ◽  
pp. 2731 ◽  
Author(s):  
Davy Verheyen ◽  
Maria Baka ◽  
Jan F. M. Van Impe

Natural antimicrobials, such as grape seed extract (GSE) and garlic extract (GE), are often used as (a part of) novel food preservation technologies, especially due to their antilisterial effect. However, little is known on the extent of sublethal injury (SI) these extracts cause to Listeria monocytogenes, possibly leading to overestimated efficacies for such novel technologies. The influence of both extracts on the sublethal injury of L. monocytogenes strain LMG23775 was investigated, also using propidium iodide staining to investigate the nature of the injury. Minimum inhibitory concentrations were 500 mg gallic acid equivalents (GAE)/L and 7.5 μg allicin/mL for GSE and GE, respectively. These concentrations slowed down the growth of L. monocytogenes, while only causing a significant amount of SI for GSE. Pure extracts caused inactivation of the cells, with GSE being the most effective. Sublethal injury from pure GSE was mainly caused by membrane damage. In pure GE, a significant amount of SI, not caused by membrane damage, was also present, albeit less pronounced than in pure GSE. In conclusion, both extracts cause a significant amount of sublethal injury to L. monocytogenes, which is not taken into account in relevant studies investigating novel food preservation applications involving natural plant extracts.


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