7 authors, including: Serena Niro Università degli Studi del Molise 25

Production of functional Ricotta cheese

Three Ricotta cheese-making trials for each experimental group were conducted on laboratory scale. All the operations guaranteed the sterility and hygiene of the product. The whey, collected after the production of pasta filata cheese from cow milk (Barone farm Vinchiaturo CB,

Italy), was mixed with 10 % milk (v/v) previously heated to 45°C. Salt was then added to 0.1 % (w/v), and heating was carried out up to 80-85°C. At this stage a solution of

citric acid (0.11 g·L^–1) was added and a gentle stirring was provided. Following coagulation, the Ricotta cheese was left to stay for 20 min, picked up and homogenised for 1 min (Bimby Vorwerk). During homogenisation, prebiotics and/ or probiotics were added. In detail, inulin or chestnut flour were added to achieve 3 g·per serving size (about 100 g). The probiotic culture of Lb. paracasei subsp. paracasei

F19 was added to reach approximately 10⁹ cfu 100 g^–1. To prepare the microbial culture, cells were overnight revitalised in MRS broth (Oxoid) at 37°C, harvested by centrifugation (5000 rpm for 10 min), washed twice in a solution of 0.9 g·L^–1 NaCl and re-suspended in 10 mL of sterile skimmed milk (Oxoid) at 37°C.

Ricotta samples were then aseptically packaged in sterilised glass jars with a cap and then cooled to 5±1°C for 7 days (Figure 1).

The description of Ricotta samples is summarised into this plan:

of each Ricotta sample was aseptically transferred into a sterile stomacher bag, diluted with 90 mL of sterile physiological solution (NaCl 9 g·L^–1) and homogenised for 1 min in a Lab-blender 400 Stomacher (Seward Laboratory, London, UK). One mL of the first dilution was used to obtain tenfold serial dilutions, utilised for microbial counts, detailed as follows:

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  Lactic acid bacteria (LAB) were counted on MRS agar (Oxoid) after 48 h of incubation at 37°C;
  
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  Enterobacteriaceae were enumerated on VRBGA (Oxoid) after 36 h of incubation at 37°C;
  
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  Total and faecal coliforms were differentiated on VRBA (Oxoid) after 36 h of incubation at 37°C and 44°C, respectively;
  
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  Yeasts and moulds were detected on YPD (36) after 72 h of incubation at 25°C;
  
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  Total bacteria were counted on PCA (Oxoid) after 48 h at 28°C.