Results of a recent pilot-scale ‘probiotic feta’ production trial were published in Food Microbiology. The research was conducted by a team from the Institute of Technology of Agricultural Products, Hellenic Agricultural Organisation DEMETER, Athens.
Addition of the bacterial strain Lactobacillus plantarum T571 as a co-starter culture in the production of a ‘probiotic feta’ cheese resulted in a product of high quality with sensory characteristics similar to those of conventional feta, the scientists revealed.
Numbers of L. plantarum in the product exceeded the threshold of 6 log colony forming units/gram (CFU/G) necessary to be classified as a probiotic food at the cold storage temperature of 4°C for nine months. Viable numbers of the strain were also maintained for 6 months (the normal commercial storage time) at the ‘abuse’ temperature of 12°C, which can occur during transportation, retail storage and household storage.
“In the present study, the performance of the new L. plantarum T571 strain with probiotic potential was tested as adjunct culture in Feta cheese manufacture, a widely consumed cheese in Greece and the entire world. L. plantarum T571 exhibited a satisfactory performance in Feta cheese, since there were no significant changes in the typical characteristics of the cheese. Furthermore, the strain was found viable and in appropriate amounts (~6.0 log CFU/g) at the end of the storage periods at 4 and 12°C,” commented corresponding author Nikos Chorianopoulos.
Probiotic inhibits pathogens
The scientists also tested the effect of the probiotic strain on pathogenic bacteria. They inoculated the probiotic product and a control cheese (lacking L. plantarum) with three strains of Listeria monocytogenes, which is widely recognised to cause severe, sometimes fatal, foodborne illnesses.
“The addition of the L. plantarum T571 strain in the samples inoculated with the three strain cocktail of the pathogen, resulted in the reduction of the pathogen in a shorter time period compared to the control samples,” said Chorianopoulos.
“During storage, L monocytogenes was found below detection limit of the enumeration method only in probiotic samples,” he added.
The study used Fourier Transform Infrared (FTIR) analysis to monitor the evolution of the microbiological characteristics of control and probiotic cheeses throughout manufacturing, ripening and long-term storage. This is the first time the technique has been used from ’end-to-end’ of the production process, the researchers explained. FTIR was also found to be valuable in predicting the sensory quality and shelf life of the cheese.
“However, to obtain better reliability of the results and examine the acceptance of the new probiotic cheeses, consumer studies should also be included in the near future,” the scientists acknowledged.
Given the global popularity of feta, combined with the growing demand for functional foods, a probiotic form of the cheese could have great potential, the researchers suggested.
“In today's global food industry, the probiotic market is encountering an unprecedented growth to conform with the consumer demand for new products with health beneficial effects. [The] Dairy industry can play a key role in the functional food production, since cheese can act as a suitable matrix for carrying probiotic microorganisms,
“Considering the growing global demand for healthy food, L. plantarum strain T571 is a promising adjunct candidate to develop functional feta cheese,” the scientists concluded.
Source: Food Microbiology
Volume: 74 (2018) pages 21-33, doi: 10.1016/j.fm.2018.02.005
“Greek functional Feta cheese: Enhancing quality and safety using a Lactobacillus plantarum strain with probiotic potential”
Authors: Olga S. Papadopoulou, Anthoula A. Argyri, Evangelos E. Varzakis, Chrysoula C. Tassou, Nikos G. Chorianopoulos.