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 effects of dried bonito stock aroma and taste on saltiness enhancement and palatability improvement in salt-reduced food.

Inclusion Criteria:

Staff or students of the Doshisha Women's College of Liberal Arts
Prior experience in sensory testing of various stocks and other foods
Informed consent was obtained.

Exclusion Criteria:

Not reported.

Description of Study Protocol:

Experiment 1

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 were prepared, each with a different kind of dried bonito (arabushi and karebushi). Each solution was used to prepare a set of five test samples of different NaCl concentrations. The stock of arabushi samples were prepared at 0.68% NaCl, 0.74% NaCl, 0.80% NaCl, 0.86% NaCl and 0.93% NaCl. The stock of karebushi samples were prepared at 0.62% NaCl, 0.70% NaCl, 0.80% NaCl, 0.90% NaCl and 1.00% NaCl.
As a control, water vapor was used in place of the dried bonito as the olfactory stimulant. The NaCl concentrations of the samples with water vapor were: 0.68% NaCl, 0.74% NaCl, 0.80% NaCl, 0.86% NaCl and 0.93% NaCl. The concentrations used were decided by a pilot study.
Each test sample was paired with a reference sample of 0.80% NaCl aqueous solution. The pairs were presented to the panelists at random. The panelists were instructed to taste and swallow each sample and sniff the aroma. They were asked which sample in the pair was saltier and which sample in the pair was more palatable.
The panelists participated in at least two of three kinds of sensory evaluations, namely, the evaluations with olfactory stimulation by the aroma of the stocks and water vapor.

Blinding Used

The panelists were not informed whether samples were test or reference samples. Color additives were used to adjust the color of samples to generate almost identical coloration.

Intervention

Stock of arabushi at five different concentrations of NaCl: 0.68% NaCl, 0.74% NaCl, 0.80% NaCl, 0.86% NaCl and 0.93% NaCl
Stock of karebushi at five different concentrations of NaCl: 0.62% NaCl, 0.70% NaCl, 0.80% NaCl, 0.90% NaCl and 1.00% NaCl.

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 or more palatable than the reference sample
A probit analysis was used to evaluate the concentration of NaCl at which 50% of the panelists could not differentiate the saltiness of an aqueous NaCl solution with olfactory stimulation from that of a reference NaCl aqueous solution with no olfactory stimulation.

Experiment 2

Design

A total of three stocks of y value (umami intensity) 0.12% were prepared (arabushi dried bonito stock, karebushi dried bonito stock and MSG aqueous solution). The y value of 0.12% was decided by a pilot study. For each stock, samples were prepared at five different concentrations of NaCl: 0.67%, 0.73%, 0.80%, 0.87% and 0.94%. The MSG aqueous solution was used as a control because MSG is tasteless, except for umami, at the concentration used in this experiment.
Each test sample was paired with a reference sample of 0.80% NaCl aqueous solution. The pairs were presented to the panelists at random. The panelists, who wore nose clips, were instructed to taste and swallow each sample. They were asked which sample in the pair was saltier and which sample in the pair was more palatable.
The panelists participated in at least two of three three kinds of sensory evaluations, namely, the evaluation of the dried bonito stocks and the MSG solution.

Blinding Used

Color additives were used to make sample colors indistinguishable from one another.

Intervention

Stock of arabushi at five different concentrations of NaCl: 0.67%, 0.73%, 0.80%, 0.87% and 0.94%
Stock of karebushi at five different concentrations of NaCl: 0.67%, 0.73%, 0.80%, 0.87% and 0.94%.

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 or more palatable than the reference sample
A probit analysis was used to evaluate the concentration of NaCl at which 50% of the panelists could not differentiate the saltiness of an aqueous NaCl solution from that of a reference NaCl aqueous solution.

Experiment 3

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

A test solution of y value (umami intensity) 0.12% was prepared using the stock of dried bonito and dried kelp. Using this stock, test samples were prepared at five different NaCl concentrations: 0.62%, 0.70%, 0.80%, 0.90% and 1.00%. These concentrations were decided by a pilot study.
Each test sample was paired with a reference sample of 0.80% NaCl aqueous solution. The pairs were presented to the panelists at random. The panelists were instructed to taste and swallow each sample. They were asked which sample in the pair was saltier and which sample in the pair was more palatable.

Intervention

Dried bonito and dried kelp stock at five different NaCl concentrations: 0.62%, 0.70%, 0.80%, 0.90% and 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 or more palatable than the reference sample
A probit analysis was used to evaluate the concentration of NaCl at which 50% of the panelists could not differentiate the saltiness of an aqueous NaCl solution from that of a reference NaCl aqueous solution.

Data Collection Summary:

Experiment 1

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

Stock of arabushi at five different concentrations of NaCl: 0.68%, 0.74%, 0.80%, 0.86% and 0.93%
Stock of karebushi at five different concentrations of NaCl: 0.62%, 0.70%, 0.80%, 0.90% and 1.00%.

Controlled Variables

NaCl aqueous solutions, with water vapor, at five different concentrations: 0.68% NaCl, 0.74% NaCl, 0.80% NaCl, 0.86% NaCl and 0.93% NaCl.

Experiment 2

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

Stock of arabushi at five different concentrations of NaCl: 0.67%, 0.73%, 0.80%, 0.87% and 0.94%
Stock of karebushi at five different concentrations of NaCl: 0.67%, 0.73%, 0.80%, 0.87% and 0.94%.

Controlled Variables

MSG aqueous solution with y value (umami intensity) of 0.12% at five different concentrations of NaCl: 0.67%, 0.73%, 0.80%, 0.87% and 0.94%.

Experiment 3

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

Dried bonito and dried kelp stock with y value (umami intensity) of 0.12% at five different NaCl concentrations: 0.62%, 0.70%, 0.80%, 0.90% and 1.00%. These concentrations were decided by a pilot study.

Description of Actual Data Sample:

Experiment 1

Initial N: 52 (52 females, zero males)
Attrition (final N): 52.

Experiment 2

Initial N: 61 (61 females, zero males)
Attrition (final N): 61.

Experiment 3

Initial N: 23 (23 females, zero males)
Attrition (final N): 23.

Age

21 to 25 years.

Location

Kyoto, Japan.

Summary of Results:

Key Findings

Experiment 1

Sensory Evaluation of Intensity of Saltiness and Palatability of NaCl Solution With Aroma of Dried Bonito Stocks
Test	Test Sample NaCl%	Size of Panel	Number of Panelists Judging Test Sample Saltier Than Reference Sample	Statistical Significance	Number of Panelists Judging Test Sample More Palatable Than Reference Sample	Statistical Significance
Water Vapor
1	0.68	52	6	P<0.05	24
2	0.74	52	10	P<0.05	26
3	0.80	52	27		21
4	0.86	52	36	P<0.05	22
5	0.93	52	43	P<0.05	8	P<0.05
Aroma of Stock of Arabushi
1	0.68	25	3	P<0.05	21	P<0.05
2	0.74	25	6	P<0.05	20	P<0.05
3	0.80	25	13		20	P<0.05
4	0.86	25	19	P<0.05	16
5	0.93	25	24		17
Aroma of Stock of Karebushi
1	0.62	25	2	P<0.05	23	P<0.05
2	0.70	25	9		21	P<0.05
3	0.80	25	14		22	P<0.05
4	0.90	25	16		21	P<0.05
5	1.00	25	23	P<0.05	16

The aroma of dried bonito does not enhance saltiness
The aroma of dried bonito, especially karebushi, improves the palatability of saltiness.

Experiment 2

Sensory Evaluation of Intensity of Saltiness and Palatability of Dried Bonito Stocks Without Aroma
Test	Test Sample NaCl%	Size of Panel	Number of Panelists Judging Test Sample Saltier Than Reference Sample	Statistical Significance	Number of Panelists Judging Test Sampe More Palatable Than Reference Sample	Statistical Significance
MSG
1	0.67	52	9	P<0.05	35	P<0.05
2	0.73	52	23		33
3	0.80	52	26		43	P<0.05
4	0.87	52	36	P<0.05	35	P<0.05
5	0.94	52	45	P<0.05	25
Stock of Arabushi
1	0.67	55	25		40	P<0.05
2	0.73	55	30		40	P<0.05
3	0.80	55	33		39	P<0.05
4	0.87	55	41	P<0.05	36	P<0.05
5	0.94	55	45	P<0.05	29
Stock of Karebushi
1	0.67	51	20		39	P<0.05
2	0.73	51	25		40	P<0.05
3	0.80	51	36	P<0.05	38	P<0.05
4	0.87	51	37	P<0.05	35	P<0.05
5	0.94	51	39	P<0.05	35	P<0.05

Tastants, other than umami substances, in dried bonito stocks have the ability to enhance saltiness.

Experiment 3

Sensory Evaluation of Intensity of Saltiness and Palatability of Karebushi-Dried Kelp Stocks
Test	Test Sample NaCl %	Size of Panel	Number of Panelists Judging Test Sample Saltier Than Reference Sample	Statistical Significance	Number of Panelists Judging Test Sample More	Statistical Significance
1	0.62	23	8		19	P<0.05
2	0.70	23	12		22	P<0.05
3	0.80	23	15		17	P<0.05
4	0.90	23	17	P<0.05	19	P<0.05
5	1.00	23	20	P<0.05	14

Stock prepared with dried bonito and dried kelp could effectively enhance saltiness and improve overall palatability of salt-reduced food.

Author Conclusion:

The saltiness enhancement of dried bonito stock was caused by the characteristic taste (with the exception of umami) of dried bonito stock and that its characteristic aroma and umami were involved in preventing the loss of palatability of low-salt diet
The characteristic aroma and taste of the stock of karebushi were effective in improving the palatability of food, regardless of the intensity of its saltiness
The karebushi-dried kelp stock, without the addition of MSG, effectively enhanced saltiness and improved the overall palatability of salt-reduced food.

Funding Source:

Government:	Japan Society for the Promotion of Science
University/Hospital:	Department of Food Science and Nutrition at 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)	N/A
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	N/A
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	N/A
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	N/A

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?	No
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?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	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?	No
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?	Yes
	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?		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?	Yes
	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?	N/A
	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)?	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?	Yes
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