UM: Umami Compounds and Sodium (2013)
To demonstrate whether or not it would be possible to reduce the NaCl content in standard Western European foods by replacing NaCl with naturally brewed soy sauce without decreasing the consumer acceptance of these foods.
- Healthy and not on a prescribed diet
- Not subject to food allergies
- In good command of the Dutch language
- All participants were compensated for participating in the study.
Not described.
Recruitment
Subjects between the ages of 18 and 60 years were selected by a local recruitment agency.
Design
Randomized controlled trial. All samples were coded with random three-digit numbers and were presented in random order to each person.
Intervention
- Three types of food were investigated: Salad dressing, soup and stir-fried pork
- An exchange rate was by which NaCl can be replaced with soy sauce without a significant change in the overall taste intensity was established per product type, by means of alternative forced choice tests
- The same consumers evaluated five samples per product type with varying NaCl and soy sauce content on pleasantness and several sensory attributes.
Statistical Analysis
- The data from the two-AFC tests were analyzed using beta-binomial statistics
- Analysis of variance was performed on the ratings of pleasantness and attribute intensity
- Once the F-test indicated a significant difference between product means, post-hoc LSD comparison of mean tests was performed to determine which means were significantly different
- Significance of differences was defined as P<0.05
- The ANOVA and post-hoc tests were performed using SPSS v 16.0.
Timing of Measurements
- Tasting sessions were conducted in the sensory laboratory of the Restaurant of the Future, Wageningen, The Netherlands
- Per product category, the consumers participated in two tasting sessions of 60 minutes each
- Per product type, first and second panel sessions were held within one week
- In the first session, the subjects were asked to perform five two alternative forced choice 2-AFC tests. The aim of the 2-AFC tests was to establish the exchange rate (ER) by which NaCl can be replaced with soy sauce without a significant change in the overall taste intensity.
- After the first session, the ER was calculated from the results of the paired comparisons and this ER was used to calculate the concentrations for the second testing session
- In the second session, panelists evaluated five samples with varying table salt and or soy sauce content twice. The aim of the second session was to establish the optimal exchange rate (OER) by which NaCL can be replaced with soy sauce in products without significant losses in both overall taste intensity and in the degree of product liking.
Dependent Variables
- Consumer acceptance of foods with decreased NaCl content:
- Subjects were asked to compare the taste and acceptance of different sample with varied NaCl content
- Subjects were asked to compare the product with the standard NaCl content with one out of five products with different soy sauce concentrations. They were asked which of the two samples had the stronger overall taste.
- Subjects evaluated five samples per product type with varying NaCl and soy sauce content on pleasantness and several sensory attributes
- An exchange rate was by which NaCl can be replaced with soy sauce without a significant change in the overall taste intensity was established per product type, by means of alternative forced choice tests.
Independent Variables
Three types of food were investigated: Salad dressing, soup and stir-fried pork.
- Commercially available liquid soy sauce was used in the preparation of the salad dressings, whereas dried Kikkoman powdered soy sauce KU-20 was used in the preparation of the soups and stir-fried pork
- All samples were coded with random three-digit numbers and were presented in random order per person
- Panelists were instructed to rinse their mouth with water and to eat cream crackers between the samples. The inter-stimulus interval was four minutes.
- Initial N: 180 subjects (60 consumers per each product category: salad dressing, soup, and stir-fried pork)
- Attrition: 165 (56 in the salad dressing category, 52 in the soup category and 57 in the stir-fried category)
- 56 subjects for salad dressing (28 male, 28 female)
- 52 subjects for soup (26 male, 26 female)
- 57 subjects for pork (26 male, 31 female)
- Age: Mean age was 38, range from 18 to 57 years
- Ethnicity: Dutch or Caucasian
- Location: The Netherlands.
Key Findings
- In pairs one to four of the salad dressing test, the overall taste of soy sauce variants was significantly perceived as stronger than that of the NaCl standard
- No significant difference in overall taste intensity was reported for pair five
- For pair one and pair two of the stir-fried pork test, the overall taste of the soy sauce variant was significantly perceived as a stronger than that of the NaCl standard
- For pair three, no significant difference in overall taste intensity was observed, whereas for pair four and pair five, the salt standard was reported to have a stronger overall taste
- Salad dressings prepared with 2% sodium chloride tasted equally intense as that prepared with 1% sodium chloride and soy sauce
- Soups prepared with 0.9% sodium chloride tasted equally intense as that prepared with 0.75% sodium chloride and soy sauce
- Stir-fried pork prepared with 0.7% sodium chloride tasted equally intense as that prepared with 0.5% sodium chloride and soy sauce
- These results can be translated into a NaCl reduction in the tested real food products of 50%, 17%, and 29% without compromising the intensity of the overall taste
- The results from the Optimal Exchange Ratio (OER) can be translated to a NaCl reduction in the tested real food products of 50%, 17%, and 29% without leading to significant losses in either overall taste intensity or product pleasantness.
The results of the present study are strong enough to support the claim that it is possible to replace NaCl in foods with naturally brewed soy sauce without lowering the overall taste intensity and to reduce the total sodium content in these foods without decreasing their consumer acceptance.
Other: | Center for Innovative Consumer Studies, Wageningen, The Netherlands |
Quality Criteria Checklist: Primary Research
|
|||
Relevance Questions | |||
1. | Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) | Yes | |
2. | Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? | Yes | |
3. | Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? | Yes | |
4. | Is the intervention or procedure feasible? (NA for some epidemiological studies) | Yes | |
Validity Questions | |||
1. | Was the research question clearly stated? | Yes | |
1.1. | Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? | Yes | |
1.2. | Was (were) the outcome(s) [dependent variable(s)] clearly indicated? | Yes | |
1.3. | Were the target population and setting specified? | Yes | |
2. | Was the selection of study subjects/patients free from bias? | Yes | |
2.1. | Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? | Yes | |
2.2. | Were criteria applied equally to all study groups? | Yes | |
2.3. | Were health, demographics, and other characteristics of subjects described? | Yes | |
2.4. | Were the subjects/patients a representative sample of the relevant population? | Yes | |
3. | Were study groups comparable? | Yes | |
3.1. | Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) | Yes | |
3.2. | Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? | Yes | |
3.3. | Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) | Yes | |
3.4. | If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? | N/A | |
3.5. | If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) | N/A | |
3.6. | If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? | N/A | |
4. | Was method of handling withdrawals described? | Yes | |
4.1. | Were follow-up methods described and the same for all groups? | Yes | |
4.2. | Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) | Yes | |
4.3. | Were all enrolled subjects/patients (in the original sample) accounted for? | Yes | |
4.4. | Were reasons for withdrawals similar across groups? | Yes | |
4.5. | If diagnostic test, was decision to perform reference test not dependent on results of test under study? | N/A | |
5. | Was blinding used to prevent introduction of bias? | No | |
5.1. | In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? | No | |
5.2. | Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) | No | |
5.3. | In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? | N/A | |
5.4. | In case control study, was case definition explicit and case ascertainment not influenced by exposure status? | N/A | |
5.5. | In diagnostic study, were test results blinded to patient history and other test results? | N/A | |
6. | Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? | Yes | |
6.1. | In RCT or other intervention trial, were protocols described for all regimens studied? | Yes | |
6.2. | In observational study, were interventions, study settings, and clinicians/provider described? | N/A | |
6.3. | Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? | Yes | |
6.4. | Was the amount of exposure and, if relevant, subject/patient compliance measured? | Yes | |
6.5. | Were co-interventions (e.g., ancillary treatments, other therapies) described? | Yes | |
6.6. | Were extra or unplanned treatments described? | Yes | |
6.7. | Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? | Yes | |
6.8. | In diagnostic study, were details of test administration and replication sufficient? | N/A | |
7. | Were outcomes clearly defined and the measurements valid and reliable? | Yes | |
7.1. | Were primary and secondary endpoints described and relevant to the question? | Yes | |
7.2. | Were nutrition measures appropriate to question and outcomes of concern? | Yes | |
7.3. | Was the period of follow-up long enough for important outcome(s) to occur? | Yes | |
7.4. | Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? | Yes | |
7.5. | Was the measurement of effect at an appropriate level of precision? | Yes | |
7.6. | Were other factors accounted for (measured) that could affect outcomes? | Yes | |
7.7. | Were the measurements conducted consistently across groups? | Yes | |
8. | Was the statistical analysis appropriate for the study design and type of outcome indicators? | Yes | |
8.1. | Were statistical analyses adequately described and the results reported appropriately? | Yes | |
8.2. | Were correct statistical tests used and assumptions of test not violated? | Yes | |
8.3. | Were statistics reported with levels of significance and/or confidence intervals? | Yes | |
8.4. | Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? | No | |
8.5. | Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? | Yes | |
8.6. | Was clinical significance as well as statistical significance reported? | Yes | |
8.7. | If negative findings, was a power calculation reported to address type 2 error? | N/A | |
9. | Are conclusions supported by results with biases and limitations taken into consideration? | Yes | |
9.1. | Is there a discussion of findings? | Yes | |
9.2. | Are biases and study limitations identified and discussed? | Yes | |
10. | Is bias due to study's funding or sponsorship unlikely? | Yes | |
10.1. | Were sources of funding and investigators' affiliations described? | Yes | |
10.2. | Was the study free from apparent conflict of interest? | Yes | |