salt, sodium reduction, and food safety

Implications of Sodium Reduction on Food Safety

and Quality

Peter J. Taormina, Ph.D., RM(NRCM)Principal Microbiologist, John Morrell Food Group

Southern California Food Industry Conference

March 6, 2013

P. Taormina - March 6, 2013

Outline

Salt and sodium reduction is now reality Review of antimicrobial effects of salts Replacement of sodium chloride with

other chloride salts Sodium reduction research and modeling Research needs


At Issue: Sodium Intake

High sodium intake increases blood pressure. Dickinson and Havas, 2007. Arch. Intern. Med.

167:1460-1468; Karppanen and Mervaala, 2006. Prog. Cardiovasc. Dis. 49:59-75; Cutler and Roccella, 2006. Hyptertension. 48:818-819.

Ave. U.S. adult - 4,000 mg/day per 2,000 calories USDA, ARS Data Tables. 1994-96 diet and health

knowledge survey. Amer. Heart Assoc. recommends <2,300 mg

salt/day


Campaigns for “Salt” Reduction

World Action on Salt and Health (WASH) Reduction in dietary salt intake of 10-15g/day

to the World Health Organization (WHO) target of 5g/day (about 2,000 mg)

Food Standards Agency, UK “No more than 6g”

Center for Science and the Public Interest FDA petition to revoke GRAS status of NaCl Reclassify NaCl as “food additive”


At Issue: Sodium Intake

Roughly 80% of daily intake from processed foods and restaurant foods. Mattes and Donnelly,

1991. J. Am. Coll. Nutr. 10:383-393

2010 Dietary Guidelines, USDA & USDHHS. www.dietaryguidelines.gov


2010 Dietary Guidelines

Reduce daily sodium intake to < 2,300 mg

Further reduce intake to 1,500 mg for about half of the U.S. population Children Majority of adults:

51 and older African American have hypertension, diabetes, or chronic kidney

disease


Sodium Intake in the United States


A Brief History of Salt

Most ancient known food preservative. Historically used to preserve meat, fish , vegetables,

fruit. Of crucial economic importance in ancient times.

Served as currency in various places at various times. Wars have been fought over it.

Roman soldiers received salt as part of their pay. “salarium argentum” → en. salary, pt. salário, es. salario

Historical association with meat and other foods. Lat. sal (salt), salsus (salty), salsicus (seasoned with salt)

en. sausage, fr. saucisse, pt. salsicha, es. salchicha en. salad, fr. salade, pt. salada, es. ensalada en. sauce, fr. sauce, pt. salsa, es. salsa

Slide courtesy of Dr. Rodrigo Tarté


Physiology of Salt

Essential mineral; must be consumed in adequate amounts.

Key roles Proper balance and acid-base

balance of body fluids. Regulation of movement of

fluids into and out of cells (together with potassium).

Regulation of blood volume and pressure.

Nerve function and muscle contraction.

11

NaSodium (Natrium)

22.98976928



Food Contributors to Sodium Intake

United States, 2007-2008*

* 75% of total intake; does not include sodium from salt added in the home during food preparation or at the table, estimated at 20% of total intake

Source: What We Eat in America, NHANES 2007-2008, Day 1 dietary intake weighted.



Food Contributors to Sodium Intake

Canada, 2004

Source: Sodium Reduction Strategy for Canada (2010) [Data from: CCHS 2.2 (Fischer PWF, Vigneault M, Huang R, Arvaniti K, Roach P (2009). Sodium food sources in the Canadian diet. Appl Physiol Nutr Metab 34:884-92)]



Current National Recommendations

United States, cont. Institute of Medicine, National Academy of Sciences

Research Need Areas Understanding of how salty taste preferences develop

throughout the lifespan. Development of innovative methods to reduce

sodium in foods while maintaining palatability, physical properties, and safety.

Enhancement of current understanding of factors that impact consumer awareness and behavior relative to sodium reduction.



Questions for Discussion

Question 2. Would reducing the salt content of food, even in a modest way, impact the safety or quality of various foods given the wide variety of technical functions for which salt is used in food?

FDA; 21 CFR Part 15; Salt and Sodium: Petition to Revised the Regulatory Status of Salt and Establish Food Labeling Requirements Regarding Salt and Sodium Public Hearing; Request for Comments


Questions for Discussion

Question 2a. How feasible would it be to mitigate this impact if true? Could it be mitigated by, for example, the addition of other ingredients?

FDA; 21 CFR Part 15; Salt and Sodium: Petition to Revised the Regulatory Status of Salt and Establish Food Labeling Requirements Regarding Salt and Sodium Public Hearing; Request

for Comments


Examples of Foods Microbiologically Preserved

by Added Sodium Chloride Ready-to-eat, refrigerated

Deli meats, bacon, hot dogs, roasts, hams, etc. Prepared salads and spreads Cottage cheese, Cheddar cheese, aged cheeses, soft

cheeses

Ready-to-eat, shelf stable Dry sausages, dry cured ham, smoked fish Processed cheese foods and spreads Pre-cooked bacon Canned foods (soups, broths, chilies, sauces, beans,

vegetables) Salad dressings, condiments


Examples of Foods Not Microbiologically Preserved by

Added Sodium Chloride* Baked breads, cereals Dry snack products

Crackers, chips, popcorn, etc. Prepared foods (boxed)

Rice packages, macaroni and cheese Frozen foods

*When foods stored properly in final packaged form


Examples of Foods in Which Preservative Properties of Sodium

Chloride is Unclear

Foods Prepared and Immediately (<1hr) Consumed at Restaurants

Foods Prepared but Not Immediately Consumed at Restaurants? Inhibition of growth during hot holding? Inhibition of growth during refrigerated

storage?


Other Sources of Added Sodium


Other Sodium Preservatives

Sodium lactate Sodium acetate and diacetate Calcium di-sodium EDTA Sodium hexametaphosphate Sodium propionate Sodium benzoate Sodium sulfite Sodium nitrite


Some sodium-containing preservative molecules used in processed foods and their contribution to total sodium per serving

Sodium-Containing Ingredient

Formula Molar Mass (g/mole)

Molar Ratio of

Na+

Typical AdditionLevels (g / 100g

serving)

mg Na+ / 100g

- chloride NaCl 58.44 0.3934 2.0 786.790

trisodium phosphate Na3PO4 163.94 0.4207 1.0 420.703

disodium phosphate Na2HPO4 141.96 0.3239 1.0 323.894

sodium tripolyphosphate Na5P3O10 367.86 0.3125 1.0 312.483

- lactate NaC3H5O3 112.06 0.2052 1.5 307.737

monosodium phosphate NaH2PO4 119.98 0.1916 1.0 191.615

- hexametaphosphate (NaPO3)6 611.77 0.2255 0.75 169.108

- metabisulfite Na2S2O5 190.11 0.2419 0.2 48.372

- citrate Na3C6H5O7 258.07 0.2673 0.15 40.088

- acetate NaC2H3O2 136.08 0.1689 0.15 25.342

- diacetate NaC4H7O4 142.09 0.1618 0.15 24.270

- propionate NaC3H5O2 96.07 0.2393 0.025 5.983

- erythorbate NaC6H7O6 198.11 0.1160 0.05 5.802

- nitrite NaNO2 68.99 0.3332 0.017 5.665

- benzoate NaC6H5CO2 144.11 0.1595 0.025 3.988

- ascorbate NaC6H7O6 198.11 0.1160 0.01 1.160

(Taormina. 2010. Crit. Rev. Food Sci. Nutr.)


Sodium-Containing Molecule

Primarily Used as Preservative

Primarily Used for Other Non-Preserving Function

Essentially Dual Use Purpose

-Chloride Shelf stable meats, fish

Processed meats, cheeses

-Nitrite Processed meats

-Lactate Processed meats

-Acetate (Diacetate)

Processed meats

-Citrate Beverages

-Polyposphates RTD beverages, syrups, sauces

Processed meats, Moisture enhanced fresh meat and poultry

-Erythorbate Processed meats

-Glutamate Various foods

-Ascorbate Various foods and beverages


Sodium Chloride: Mechanism of Action

Lowering of aw Plasmolysis

Interference with substrate utilization (3-7% NaCl [w/v]) Phosphohexose

isomerase Isocitrate

dehydrogenase Aldolase

Chloride ion


TEM (28,500x) of 24-h E. coli O157:H7 cultures in BHI with

NaCl at 0%, 5%, and 10%

M. Hajmeer et al. 2006. Food Microbiology 23: 446–452

0% NaCl 5% NaCl 10% NaCl


TEM (28,500x) of 24-h S. aureus culture in BHI with NaCl at 0%, 5%, and 10%


0% NaCl 5% NaCl 10% NaCl


Effect of NaCl on Cells

Extra coarse grade NaCl seemed to have a milder effect compared to fine grade with respect to cell damage

24h cells were more affected than 12h cells



Main Intrinsic Properties of Perishable Foods That Affect

Microorganisms Moisture

% Moisture Water activity (aw)

Equivalent Relative Humidity Vapor pressure product / vapor pressure water

Moisture:Protein ratio % Brine Concentration (Water-Phase Salt)

Acidity pH

Preservatives Salt Benzoate, sorbate, lactates, diacetate, nitrite, etc. Polyphosphates


Influence of Solute on Minimum aw for Bacterial Growth

Organism Min. aw for growth in

NaCl Glucose* Glycerol

Clostridium perfringens 0.970 0.960 0.950

Clostridium botulinum type E 0.970 - 0.940

Lactobacillus helveticus 0.963 0.966 0.928

Streptococcus lactis 0.965 0.949 0.924

Pseudomonas fluorescens 0.957 - 0.940

Vibrio parahaemolyticus 0.948 0.984 0.937

Adapted from: Sperber, 1983. J. Food Prot. 46:142-150

* Glucose not sterilized separately from media; inhibitory nonenzymatic browning products may have been present


Death Rates of Pathogens in Natural Sheep Casings at 20ºC at Different aw

Levels

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.7 0.8 0.9 1

aw-levels

De

ath

Ra

te (

log

CF

U/d

ay

)

E. coli O157:H7

S. Typhimurium

L. monocytogenes

S. aureus

Adapted from Wijnker et al., 2006. Food Microbiol. 23:657


Clostridium perfringens Growth During Cooling of Ham and Beef

3% NaCl completely inhibited growth during exponentially declining temperatures from 54.4 to 8.5°C in 21h

≤ 2% NaCl permitted growth in ham cooled in ≥18h and in beef cooled in ≥15h

Zaika, 2003. J. Food Prot. 66:1599-1603


aw Suppression with Binders

Shelf stable fish sausage with 3.2% salt was formulated to aw of 0. 97-0.92 with egg white solids and combinations of egg white solids, non-fat dry milk, propylene glycol, and soy protein isolate.

Spores of PA 3679 germinated at 0.924, but did not grow at < 0.950

Macromolecular food binders viable alternative to high levels of salts

Nieto and Toledo. 1989. J. Food Sci. 54:1129-1135.


Firmness of Reduced Sodium Sausages with Carrageenan

Ruusunen et al., 2003


Saltiness of Reduced Sodium Sausages with Carrageenan



Flavor Intensity of Reduced Sodium Sausages with Carrageenan



Reduced-Sodium Processed Cheese Foods and Spreads

Incorporation of delta-gluconolactone as a delayed acidulant reduced the pH of cheeses to 5.26, which contributed to inhibition of C. botulinum.

All potassium emulsifiers allowed toxin production suggesting that sodium and potassium ions are not equivalent in effecting inhibition of C. botulinum.

Karahadian et al., 1984. J. Food Prot. 48:63-69


Ion Replacement – Spoilage Organisms

Nielsen and Zeuthen. 1987. Intl. J. Food Microbiol. 4:13-24


Ion Replacement - Pathogens

Nielsen and Zeuthen. 1987. Intl. J. Food Microbiol. 4:13-24


Ion Replacement - Pathogens

Nielsen and Zeuthen, 1987. Intl. J. Food Microbiol. 4:13-24


Ionic Strength Comparisons When ionic strength equivalents of KCl and

MgCl2 were compared with NaCl at 2.50 and 1.25% against Micrococcus, Moraxella, and Lactobacillus inoculated into ground pork there were no significant differences between ions after ten days of storage at 5°C.

Highest reduction of the aerobic mesophilic microflora of pork sausage by CaCl2 followed by NaCl>KCl.

Terrell, R. N., M. Quintanilla, C. Vanderzant, and F. A. Gardner. 1983. J. Food Sci. 48:122-124


Comparisons of Ionic Strengths

Challenge study data was used to construct an Anti-yersinial index (AI) to represent the comparative inhibitory properties of chloride salts against Yersinia enterocolitica in pork.

The index reflected that CaCl2 was most efficient against serotype O:3 while the higher concentrations of KCl (1.8 and 2.2% w/w Cl¯) were most efficient against serotype O:8.

Raccach, M., and E. C. Henningsen. 1997. Food Microbiol. 14:431-438.


Battey et al., 2002. Appl. Environ. Microbiol. 68:1901-1906

The Effects of pH and Sodium Benzoate on Probability of Growth of a C. lipolytica, S.

cerevisiae, and Z. bailii Cocktail - Model Bev. 100ppm Potassium Sorbate, 8wks


Sodium Benzoate in Beverages

Decreasing the pH of the beverage would permit less potassium sorbate and/or sodium benzoate to achieve the same probability of yeast growth.

Conversely, increasing preservative levels provides microbial stability at increased pH levels.

Potassium benzoate vs. sodium benzoate Successful preservation in non-caloric beverages Offsets sodium per serving due to non-caloric

sweeteners


Effect of NaCl and Sucrose Concentrations on the Growth Response

of Yeasts at Different pH Values

Praphailong and Fleet. 1997. Food Microbiol. 14:459-568.


NaCl and Heat Resistance

Juneja and Eblen, 1995. J. Food Prot. 58:813-816

Z values

10.08

8.82

8.47



Bacillus cereus strains exposed to increasing concentrations of NaCl for 30min; thermotolerance assessed at 50ºC Both strains showed enhanced

thermotolerance after pre-exposure to non- lethal salt stress conditions in the exponential phase; less pronounced for stationary phase cells.

de Besten et al., 2006. Appl. Environ. Microbiol.



Organism Effect of Added NaCl on Heat Resistance

Reference

Escherichia coli Increased Calhoun and Frazier, 1966

Staphylococcus aureus Increased

Pseudomonas fluorescense Decreased

Salmonella (heat sensitive) Increased Baird-Parker et al., 1970

Salmonella (heat resistant) Decreased


What if?

“A reasonable interim target is a 50% reduction in sodium in processed foods.”

Stephen Havas, MD, MPH, MS

Barry D. Dickinson, PhD

Modena Wilson, MD, MPH

JAMA, Vol. 298, No. 12


What if 50% Reduction in Sodium? – PMP 7.0 Modeling

CSPI, 2005. Salt Assault: Brand Name Comparisons of Processed Foods Selected food

examples

Modeled with reported NaCl and 50% reduced NaCl


What if 50% Reduction in Sodium? – PMP 7.0 Growth Modeling

96% Fat Free Honey Roasted and White Turkey Breast. 1180 mg sodium / 100g

Pathogen PMP Growth Conditions

Time to Growth, Regular NaCl

Time to Growth, 50% Reduced NaCl

L. monocytogenes Broth culture (aerobic); 7.2ºC; 1-log increase

60.9 h 57.7 h

S. aureus Broth culture (aerobic); 19ºC; 3-log increase

25.2 22.8 h


Inhibition of L. monocytogenes on Regular & Reduced Sodium Ham Slices as Affected by Formulated Inhibitors and NaCl:KCl (Lite Salt)

During Vacuum-Packaged Storage at 4.4oC (40oF)



Hardwood smoked bacon; 2070 mg sodium / 100g


Time to Growth, Regular NaCl

Time to Growth, 50% Reduced NaCl

S. aureus Broth culture (aerobic); pH 6.0; 42ºC; 3-log increase

10.4 h 10.1 h

C. perfringens Broth culture (anaerobic); pH 6.0; 42ºC; 1-log increase

5.1 h 2.9 h



Pasteurized prepared cheese product (unrefrigerated); 1570 mg/100g


Max. Probability of Growth, Regular NaCl

Max. Probability of Growth, 50% Reduced NaCl

Proteolytic

C. botulinum

Broth culture (anaerobic); pH 6.5; 25ºC

0.52 0.58


Antimicrobial Alternatives Plant Derived

Glucosinolates (Isothiocyanates) – Cruciferaceae Lignans Saponins (Yucca, asparagus) Catechins (EGCG) – Green tea Hops beta-acids Fruit juices & extracts (acids & phytochemicals) Spices - essential oils & solvent extracts


Antimicrobial Alternatives

Plant Derived Spices - Essential oils & solvent extracts

Source Antimicrobial Components

Cinnamon Cinnamic Acid, Cinnamaldehyde

Clove Eugenol

Garlic Allicin

Mustard Allyl-isothiocyanate

Oregano Carvacrol, thymol

Vanilla Vanillin

Thyme Thymol

Rosemary α- Pinene, Camphor, Verbenone, 1, 8-Cineole


Antimicrobial Alternatives Chemical

Inorganic salts: NaCl, KCl, MgCl, CaCl2, NaNO2

Organic salts: lactate, diacetate, citrate, propionate

Organic acids: lactic, acetic, citric, propionic, malic etc.

Fatty acid based: lauric arginate, octanoic acid Weak acids: benzoic, sorbic Phenolics: smoke fractions, synthetic phenolics Other: hexametaphosphate, metasilicate,

sulfite, EDTA


Antimicrobial Alternatives

Microbial Derived Bacteriocins

nisin, pediocin, sakacin, reuterin, leucocin Fermentation products (combinations of acids,

peptides & bacteriocins) Antimycotics

natamycin “Live” microorganisms

Lactic acid bacteria, Carnobacterium maltaromaticum Phage

Virus that infects bacteria Listeriaphage, coliphage, etc.


Synergistic effect of an oregano-and-cranberry mixture on inhibition of L. monocytogenes on beef slices, pH 6.0

Lin et al., 2004. Appl. Environ. Microbiol. 70(9):5672


Conclusions

Salt (Sodium chloride) is the oldest and most widely used inhibitory compound in foods.

Reduction of NaCl from processed foods should be based on results of appropriate research. Research on impact of salt reduction on restaurant

foods is particularly lacking. Hot holding Cooling and cold storage Reheating

Replacement of NaCl with antimicrobial herbs and spices has not been thoroughly researched.


Conclusions Other sources of sodium should be considered. Reduced sodium products should be validated

with challenge studies. For thorough reviews on Salt, Sodium and Food

Safety see: Doyle and Glass, 2010. Comp. Rev. Food Sci. and

Food Safety. 9:44-56. Taormina, 2010. Crit. Rev. Food Sci. and Nut., 50: 3,

209-227. Sofos, 1983. J. Food Safety. 6:45-78. Reddy and Marth, 1991. J. Food Prot. 54:138-150.

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