EAL

UM: Umami Compounds and Sodium (2013)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To examine the effect of the flavor of dried bonito stock on saltiness enhancement. The study consisted of two experiments:

Experiment One: The effect was evaluated in a model solution
Experiment Two: The effect was evaluated in two everyday Japanese foods.

Inclusion Criteria:

Staff or students of the Department of Food Science and Nutrition at Doshisha Women's College of Liberal Arts
Selected by the results of a pre-experiment on NaCl threshold and had experience in sensory tests on various stocks and other foods
Informed consent was obtained.

Exclusion Criteria:

Not reported.

Description of Study Protocol:

Experiment One

Recruitment

Study panelists were staff or students of the Department of Food Science and Nutrition at Doshisha Women's College of Liberal Arts who volunteered to participate in the experiment.

Design

Two test solutions of y value (umami intensity) 0.12% were prepared:
- 6% dried bonito stock
- 0.12% MSG aqueous solution
Each solution was used to prepare a set of 5 test samples of different NaCl concentrations:
- 0.62% NaCl
- 0.70% NaCl
- 0.80% NaCl
- 0.90% NaCl
- 1.00% NaCl
MSG aqueous solution was used as a control because MSG does not have any flavor except umami at the concentration used in this experiment
Each test sample was paired with a reference sample consisting of 0.80% NaCl aqueous solution. The pairs were presented to the panelists at random. The panelists were instructed to taste each sample in the pair and indicate which was saltier.

Intervention

6% dried bonito stock at five different concentrations of NaCl:

0.62%
0.70%
0.80%
0.90%
1.00%.

Statistical Analysis

A paired comparison test (two-sided test) was used to determine statistical significance related to the number of panelists who judged the test sample saltier than the reference sample
A probit analysis was used to evaluate the concentration of NaCl at which 50% of the panelists could barely differentiate the dried bonito stock or the MSG solution in saltiness from the reference 0.80% aqueous solution. An X² test was used to determine significance.

Experiment Two

Recruitment

Study panelists were staff or students of the Department of Food Science and Nutrition at Doshisha Women's College of Liberal Arts who volunteered to participate in the experiment.

Design

Session One: Traditional Japanese clear soup was prepared using 2% dried bonito stock (the concentration usually used for everyday Japanese foods) at five different concentrations of NaCl: 0.58%, 0.64%, 0.70%, 0.76% and 0.83%. Using 0.0094% MSG aqueous solution in place of the dried bonito stock, another set of test samples were prepared at the same concentrations of NaCl. Each test sample was paired with a reference sample of 0.70% NaCl aqueous solution, the standard concentration of NaCl in traditional Japanese clear soup.
Session Two: Steamed egg custard was prepared using 2% dried bonito stock (the concentration usually used for everyday Japanese foods) at five different concentrations of NaCl: 0.75%, 0.82%, 0.90%, 0.98% and 1.07%. Using 0.0094% MSG aqueous solution in place of the dried bonito stock, another set of test samples were prepared at the same concentrations of NaCl. Each test sample was paired with a reference sample consisting of stock-free steamed egg custard containing 0.90% NaCl, the standard concentration of NaCl in steamed custard.
In each session, the pairs were presented to the panelists at random. The panelists were instructed to taste each sample in the pair and indicate which was saltier. Panelists were also asked to score each test sample for palatability on a seven-point scale from extremely palatable (+3) to extremely unpalatable (-3).

Intervention

Session One (traditional Japanese clear soup): 2% dried bonito stock at five different concentrations of NaCl: 0.58%, 0.64%, 0.70%, 0.76% and 0.83%
Session Two (egg custard): 2% dried bonito stock at five different concentrations of NaCl: 0.75%, 0.82% , 0.90%, 0.98% and 1.07%.

Statistical Analysis

A paired comparison test (two-sided test) was used to determine statistical significance related to the number of panelists who judged the test sample saltier than the reference sample.
A probit analysis was used to evaluate the concentration of NaCl at which 50% of the panelists could barely differentiate the test sample in saltiness from the reference sample. ANOVA with Tukey's method was used to analyze the data on palatability. An X² test was used to determine significance.

Data Collection Summary:

Evaluation One

Timing of Measurements

Sensory evaluations were conducted one time for each panelist.

Dependent Variables

Perception of saltiness (self-reported).

Independent Variables

6% dried bonito stock at five different concentrations of NaCl:

0.62%
0.70%
0.80%
0.90%
1.00%.

Controlled Variables

0.12% MSG aqueous solution at 5 different concentrations of NaCl:

0.62%
0.70%
0.80%
0.90%
1.00%.

Evaluation Two

Timing of Measurements

Sensory evaluations were conducted one time for each panelist.

Dependent Variables

Perception of saltiness (self-reported)
Palatability ratings (self-reported).

Independent Variables

Session One (traditional Japanese clear soup): 2% dried bonito stock at five different concentrations of NaCl: 0.58%, 0.64%, 0.70%, 0.76% and 0.83%
Session 2 (egg custard): 2% dried bonito stock at five different concentrations of NaCl: 0.75%, 0.82%, 0.90%, 0.98% and 1.07%.

Controlled Variables

Session One (traditional Japanese clear soup): 0.0094% MSG aqueous solution at five different concentrations of NaCl: 0.58%, 0.64%, 0.70%, 0.76% and 0.83%
Session Two (egg custard): 0.0094% MSG aqueous solution at five different concentrations of NaCl: 0.75%, 0.82 %, 0.90%, 0.98% and 1.07%.

Description of Actual Data Sample:

Initial N

Experiment One: 23 (23 females, zero males)
Experiment Two: 96 (96 females, zero males).

Attrition (final N):

Experiment One: 23
Experiment Two: 96.

Age

21 to 25 years.

Location

Kyoto, Japan.

Summary of Results:

Key Findings

Experiment 1

Test	Test Sample NaCl %	Percentage of Panelists Judging the Test Sample Saltier Than the Reference Sample	Statistical Significance
MSG
1	0.62	8.7	P<0.05
2	0.70	17.4	P<0.05
3	0.80	39.1
4	0.90	73.9	P<0.05
5	1.00	95.7	P<0.05
Dried bonito stock
1	0.62	39.1
2	0.70	52.2
3	0.80	69.6
4	0.90	73.9	P<0.05
5	1.00	82.6	P<0.05

Panelists could not distinguish the intensity of saltiness of the test sample prepared with 0.12% MSG solution from that of the reference sample in test three, but could make the distinction in tests one, two, four and five
Panelists could not distinguish the intensity of saltiness of the test sample prepared with 6% dried bonito stock from that of the reference sample in tests one and two, but could make the distinction in tests three, four and five
Saltiness enhancement could not be detected in the 0.12% MSG solution but was detectable in 6% dried bonito stock.

Experiment Two

Traditional Japanese Clear Soup
Test	Test Sample NaCl %	Percentage of Panelists Judging the Test Sample Saltier Than the Reference Sample	Statistical Significance
MSG
1	0.58	14.4	P<0.05
2	0.64	22.9	P<0.05
3	0.70	45.7
4	0.76	54.3

In test two, MSG from that of the reference sample (P<0.01). The test sample prepared with 2% bonito stock did not show a significant difference in intensity of saltiness from the reference sample
Saltiness enhancement by dried bonito stock could not be clearly identified in traditional Japanese clear soup
The test samples of MSG soup and dried bonito soup did not differ significantly in palatability.

Steamed Egg Custard
Test	Test Sample NaCl %	Percentage of Panelists Judging the Test Sample Saltier Than the Reference Sample	Statistical Significance
MSG
1	0.75	6.9	P<0.05
2	0.82	27.6	P<0.05
3	0.90	44.8
4	0.98	72.4	P<0.05
5	1.07	86.2	P<0.05
Dried Bonito Stock
1	0.75	20.7	P<0.05
2	0.82	58.6
3	0.90	65.5
4	0.98	89.7	P<0.05
5	1.07	100.0	P<0.05

Panelists did not discriminate the intensity of saltiness of the test sample prepared with 2% dried bonito stock from that of the reference sample in tests two and three
The test sample prepared with 0.0094% MSG solution was distinguished from the reference sample in tests one, two, four and five
Palatability of dried bonito sample was generally superior to that of the MSG sample
Dried bonito stock enhanced saltiness and improved palatability in the egg custard samples
The characteristic flavor, other than umami, of dried bonito stock probably contributed to the positive effects, because MSG solution did not show the same effects.

Author Conclusion:

The characteristic flavor of dried bonito stock induced saltiness enhancement. In everyday Japanese food, the flavor of dried bonito stock could enhance saltiness and prevent the loss of palatability that would otherwise result from reduced salt content.

Funding Source:

University/Hospital:

Doshisha Women's College of Liberal Arts

Reviewer Comments:

Study reported "health was checked," but did not elaborate
Population sampled not diverse, with females only (unclear if this would affect results).

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?	???
2.	Was the selection of study subjects/patients free from bias?		No
	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?	No
	2.2.	Were criteria applied equally to all study groups?	No
	2.3.	Were health, demographics, and other characteristics of subjects described?	No
	2.4.	Were the subjects/patients a representative sample of the relevant population?	???
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?	N/A
	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?		Yes
	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.)	Yes
	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?		N/A
	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?	N/A
	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?	N/A
	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)?	N/A
	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