Salt in Cheese: A Matter of Food Safety or Technology?

Salt in Cheese: A Matter of Food Safety orTechnology?Steve Labrie andMichel BrittenInstitute of nutrition and functionalfoods (INAF)Dairy Science and TechnologyCentre (STELA)Food Research and DevelopmentCentre (FRDC)Agriculture and Agri-Food Canada

The research team• Florie Aguer• Esthelle Berthet-Rayne• Josiane Caplette• Joanie Côté• Carl Cyr• Kathya Dupont• Vanessa Duval-Tougas• Valérie Goulet-Beaulieu• Augustin Goblet• Davy Grava• Justine Hell• Violaine Jan• Ingrid Kombou• Geneviève Lanouette• Marie-Hélène Lessard• Léa Maire• Geneviève Savoie• Emmanuelle Stephan• Émilie Tétreault• Marilyne Touchette• Marc-André Therrien• Mariette Beaudet• Gaétan Bélanger• Francis Boileau• Annie Caron• Nancy Graveline• Brïte Pauchet• Nathalie Rémillard• Sophie Turcot• Catherine Viel• Michel Britten• Ismail Fliss• Jacinthe Fortin• Steve Labrie• Daniel St-Gelais2

A project from the Dairy Cluster I3

HighlightsA. Why reduce sodium in food supply?1. Nutritional aspects2. The Health Canada’s sodium reduction strategyB. Challenges of sodium reduction in cheeses1. Roles of salt in food in cheese safety2. Technological role of sodium in cheese4

A. Why reduce sodium in thefood supply?5

A.1- Sodium in food - Nutritional aspects• Sodium is contained in salt andmany other ingredients• Sodium is essential in humandiet having many physiologicalrolesExcess of sodium, daily intake of 3 400 mg Na / dayNa excessHigh bloodpressure• CVD• Stroke• Kidney diseasesSources: Sodium reduction strategy for Canada. Marilyne Touchette (2013)6

Sodium reduction strategy for CanadaActual sodium intake : 3 400 mg / dayObjective 2016 : UL = 2 300 mg / day• Awarness and education• [Na] processed foods• Research• Monitoring and evaluationSource: Marilyne Touchette, Sodium reduction strategy for Canada7

Contribution of processed food8Source: Sodium reduction strategy for Canada

B. Challenges of Sodium Reductionin Food Supply10

IV. The roles of salt in cheese1. Acts as a barrier against pathogens2. Controls starter activity3. Modulates secondary flora and ripening flora4. Affects the activity of enzymes that areresponsible for ripening5. Controls the texture and functionalproperties of cheese6. Controls syneresis and moisture7. Adds to the taste11

Our research projectNatural cheeses, sodium reduced cheeses and salt substitutionSpeciality cheesesCheddarMozzarellaMicrobiological effect- Pathogens- Useful bacterial microflora-Starters- Adjunct cultures- Useful fungal microfloraPhysico-Chemical effect- Mineral equilibrium- Texture control- Salt distribution- Cohesion- Salt replacement- Melting propertiesÉvaluationsensorielle- Texture- Sensory profile- Cohesiviness- Élasticity12

Hurdles against pathogens• The pathogens growth could be affected bymany hurdles.pH13

Effect of sodium reduction on themicroflora• Pathogenic bacteria• Listeria monocytogenes• Staphylococcus aureus• Lactic acid bacteria• Lactococci• Lactobacilli• Streptococci• Fungal microorganisms• Penicillium camemberti• Geotrichum candidum14

Cheese model curd• Camembert• Cheddar15

L. monocytogenes -Camembert914 o C, 95% RH 4 o CListeria monocytogenes (log cfu/g)87654320 5 10 15 20 25 30 35Ripening time (days)16

Listeria monocytogenes - Cheddar17

Salt is not a major growth hurdlefor L. monocytogenes• NaCl reduction up to 30 % in Cheddar andCamembert cheeses generate similare growthprofiles.• New questions:• Other pathogens and spoiling bacteria?• In « real » cheese?18

In real cheese?19

Consequences of salt reductionpH20

Consequences of salt reductionpH21

Consequences of salt reductionpH22

Consequences of salt reductionpH23

Consequences of salt reductionpH24

Partial conclusion• Salt is a minor hurdle for the growth of Listeriamonocytogenes and Staphylococcus aureus.• Salt have an impact on the bacterial startercultures and the observed activity is straindependent• Fungal ripening culture seems only lightlyaffected by salt reduction.25

B.2- Technological roles of sodiumImpact of salt on cheese qualityTaste• Direct effect: salty taste• Indirect effect: enzyme activity• Proteolysis ↓ (especially ‐casein)Texture• Physicochemical contribution• Cheese salting: osmotic pressure (humidité ↓)• Protein hydration• Swelling (free water ↓)• Emulsifying activity (free oil ↓)• Colloidal calcium• Cation exchange ???• Enzymatic contribution• Proteolysis ↓26

Impact of salt on cheese qualityColor• Decrease whiteness• Swelling and fusion of paracasein « particles »(reduced interfacial area)… In addition to the salty taste,Salt reduces:-bitterness-moisture-free oil-opacitySalt increases:-firmnessSalt controls:-ripening(texture and flavor)27

Impact of salt on cheese rheology• Experimental approach• Pilot plant cheese productions• Target [NaCl]: 1.9, 1.6, 1.3%• Cheese analysis• Frequency sweep test at 22°C• Melting profile (5 à 90°C)• Rigidity complex modulus (G*) at 22°C• Melting temperature (G’ = G”)• Rigidity complex modulus(G*) at 75°C (melt)28

Impact of salt on cheese rheology• ResultsRigidity modulus 22°C18017070Melting temperatureRigidity modulus 75°C3,53,0G* 22°C (Kpa)16015014013012020%Temperature °C6560555°CG* 75°C (Kpa)2,52,01,51,060%1100,51001,9% 1,6% 1,3%[NaCl] %501,9% 1,6% 1,3%[NaCl] %0,01,9% 1,6% 1,3%[NaCl] %[NaCl] decrease from 1.9 to 1.3%1.7% moisture increase29

Model system to control cheese mineralcomposition• Diffusion cell• Production of non salted cheese• Cutting of cheese disc• Diffusion treatmentDiffusion buffer (UF whey permeate)Non salted cheese disc(70 x 3 mm)• Salt is added to diffusion buffer tomeet salt content target• Control final disc weight (moisture)• Vacuum packaging and saltdistribution equilibrium (4°C)Optimal conditions• Temperature 22°C• Contact time 60 min• Orbital shaking 50 rpm30

Model system to control cheese mineralcomposition• Diffusion cell• Amount of salt added to the bufferto meet salt/moisture target incheese[NaCl] buffer = (S/M target – 0.736)/0.498R 2 =0.9873• Moisture controlS/M (%)4,03,53,02,52,01,51,0• Control calcium equilibrium• Use of CaCl 2 , NaCit,phosphates…0,50,00 1 2 3 4 5[NaCl] buffer (%)31

Impact of salt and calcium equilibrium on cheesetexture (constant moisture)• Experimental approach• Factorial experimental design• [NaCl] in cheese (5): 0.4 à 2%• Colloidal calcium (3): 10 – 25 mg/g protein• Salts added to diffusion buffer: NaCl, CaCl 2 , NaCit• Analyses• Texture profile analysis (TPA)• Cheese rheology• Frequency sweep test at 22°C• Melting profile (5 à 90°C)32

Impact of salt and calcium equilibrium on cheesetexture (constant moisture)• ResultsTexture at 22°C170,58• Reduction in salt 1.75 à 0.35%• ↓ Firmness (25%)• non linear• ↑ Cohesion (7%)Firmness (N)16151413120,560,540,52Cohesion110,5• Colloidal calciumnon significant effect…21,5 1 0,5[NaCl] (%)033

Impact of salt and calcium equilibrium on cheesetexture (constant moisture)• ResultsRheology at 75°C (melt)• Salt reduction• ↓ Rigidity modulus• Increase colloidal calcium• ↑ Rigidity modulusG* 75°C (KPa)1,81,61,41,210,80,60,421,5 1 0,5[NaCl] (%)G* 75°C (KPa)1,61,51,41,31,21,110,90,8010 15 20 25[Ca coll ] (mg/g)Colloidal calcium "offsets" the loss of viscosity of melted cheesecaused by the reduction of salt content34

Conclusions• Reducing salt content induces significant texturechanges in cheese (loss of firmness, loss of meltviscosity);• These changes cannot be explained by highermoisture of reduced salt cheeses;• Colloidal calcium showed little effect on cheesetexture at room temperature, but significantlyincreased the viscosity of melted cheese.• May correct melting defects of low salt cheese…35

Thank you !