Summary: A survey of 115
people from China showed that 87 of these (75.7%) answered the question “Do you
like the taste of soy milk (豆浆)?” with “Yes”.
Background: A recent
article by Verduci et
al. (2019) in the nutritional sciences journal Nutrients has stated that “Unfortunately, a well-known
disadvantage of soy milk preparation is a characteristic beany flavor” (Verduci et al. 2019) . This quite
obviously is a subjective claim – something that should not be presented as an
objective observation in the scientific context. Verduci et al. also made this
statement in the context of feeding infants who are not yet accustomed to
either the characteristic taste of soy milk or that of cow’s milk.
There are
different kinds of soy milk in China. Traditional soy milk (“soy pulp”,
Dòujiāng, 豆浆) is made from soy beans and water.
Sugar or salt may be added. There are other kinds of soy milk in China, and
these have different Chinese names. There is fermented soy milk, a specialty of
Beijing (“bean juice”, Dòuzhī, 豆汁; as far as I can tell this is made from mung beans, not soy beans),
and “colorful soy milk” (“grain soy milk”, Wǔgǔ dòujiāng, 五谷豆浆) which
includes many ingredients such as millet, black rice, buckwheat, oats, red
beans, sugar, etc. Processed soy milk may be called “Dòunǎi” (“soy milk”, 豆奶) – in contrast to freshly-made,
traditional soy milk (“soy pulp”, Dòujiāng, 豆浆).
It was the hypothesis
of this survey that the majority of participants would answer the question “Do
you like the taste of soy milk?” with “Yes”.
Methods: 135 people from
China received the following message on an internet language learning app: “Hi,
I’m doing a survey with people from China: Do you like the taste of soy milk (豆浆)?” All recipients of this question were from China, in this case
including Hong Kong and Taiwan, and were native speakers of Chinese (Mandarin).
Their age and gender information was taken from their profiles. The age given on
the profiles might not always have been completely accurate. Based on their
profile information almost all of the participants live in China, while a few
live in Europe (exact number not quantified). Based on their profile pictures
all participants were of what is commonly referred to as “Han Chinese”
ethnicity.
Answers classified
as “yes” or “no” were clear statements of “Yes, I like the taste” or “No, I do
not like the taste”. Answers with the following statements were classified as
“OK”: “neither like nor dislike”, “just so so”, “OK but not a big fan”, “OK but
not very like”, “OK but don’t love”, “OK with it”, and “I don’t hate it”.
Results: 116 recipients of
the question replied. One of these replied “I don’t know”. Out of the remaining
115 participants, around 62% were female, and around 38% were male.
Around 76% replied
“Yes”, while around 10% replied that the taste is “OK, but not great”, and
around 14% replied that they do not like the taste of soy milk. See tables
below.
Answers given by
participants (n = 115)
|
||
Answer
|
Number
|
Percentage
|
Yes
|
87
|
75,7
|
OK
|
12
|
10,4
|
No
|
16
|
13,9
|
Gender distribution of
participants (n = 115)
|
||
Gender
|
Number
|
Percentage
|
Female
|
71
|
61,7
|
Male
|
44
|
38,3
|
Age (years) distribution
of participants (n = 115)
|
|
Mean
|
25,0
|
Median
|
24,0
|
Standard deviation
|
6,2
|
Minimum
|
18
|
Maximum
|
53
|
There was no statistically
significant difference in age between the two genders (male/female). Kruskal
Wallis test, p-value = 0.947
Age (years)
distribution of participants by gender (n = 115)
|
|||
Gender
|
Number of participants
|
Average age
(= mean)
|
Standard deviation
|
Female
|
71
|
25,01
|
6,00
|
Male
|
44
|
25,09
|
6,58
|
There was no statistically significant
difference in age between the three answer groups (“yes”, “OK”, “no”). Kruskal
Wallis test, p-value = 0.881 
("OK" as in "The taste is OK".)
There was no statistically
significant difference in answers given between the two genders (male/female).
Chi-square test, p-value = 0.498
Answers given stratified by gender (n = 115)
|
|||
Answer
|
Female
|
Male
|
Both genders
|
No
|
12
|
4
|
16
|
OK
|
7
|
5
|
12
|
Yes
|
52
|
35
|
87
|
Total
|
71
|
44
|
115
|
There was no statistically
significant difference in answers given between the age group of <25 years
and ≥25 years. Chi-square test, p-value = 0.631
Answers given stratified by age group (n =
115)
|
|||
Answer
|
Number of participants
<25 years old
|
Number of participants
≥25 years old
|
Number of participants,
all ages
|
No
|
8
|
8
|
16
|
OK
|
8
|
4
|
12
|
Yes
|
46
|
41
|
87
|
Total
|
62
|
53
|
115
|
Discussion:
One limitation of
the survey is the relatively small number of participants. Another limitation
is that information on which Chinese provinces the participants came from was
not collected. A further limitation is the selection bias due to the fact that
all participants were users of a language learning app.
In a study in the
United States, Lawrence
et al. (2016) found that “Age had no effect on overall liking, while
ethnicity did (Caucasian/African American compared with Asian; P <
0.05). Caucasians/African Americans differentiated soymilks more than Asians [They
probably mean of East Asian ethnicity] and assigned a wider range of liking
scores than Asians (2.1 to 7.2 compared with 4.0 to 6.1). Three consumer
clusters were identified. Sweet taste with vanilla/vanillin and sweet
aromatic flavors and higher viscosity were preferred by most consumers […].
Drivers of dislike were not identified for Cluster 1 consumers while Clusters 2
and 3 consumers (n = 84, n = 80) disliked beany, green/grassy and meaty/brothy
flavors and astringency. […]
[…]
[…] Age had no
effect on U.S. consumer liking of soymilk, but ethnicity did have an effect.
Asians did not use the full range of the hedonic scale, and all overall liking
scores were centered around the middle of the scale, while Caucasian and
African American U.S. consumers used a much wider range of the hedonic scale.
[…] Universal drivers of liking were vanilla/vanillin and sweet aromatic
flavor, sweet taste, and a higher viscosity with differences among consumers
for sweet taste intensity and tolerance for beany and cereal flavors and bitter
taste. These findings can aid product developers to create a soymilk that is
appealing to a wide population, and also to reach segments of the population
that have not yet been accommodated.” (Lawrence et al. 2016)
What about the “beany flavor”?
Verduci et al.
2019 were referring to Sethi
et al. 2016 regarding the expression “beany flavor” – however, the beany
flavor has been discussed in the literature since the 1970s (Sethi et al. 2016) .
The Merriam Webster
dictionary states: “beany […] of an
oil: marked by an off-flavor suggestive of that of beans”.
--- Technical
stuff:
Sethi et al.
(2016) wrote: “Traditional
process of soy milk preparation leaves a product with limited shelf life
and a characteristic beany
flavor. Modern soy
milk production utilizes advanced technologies and equipments to
maximize nutritional value, shelf-life and convenience with reduced beany flavor
(Table 2). In view of its popularity, a wide array of variants is
available in the market. Based on solids concentration, available variants are
light, dairy like, and rich soy milk, with respect to formulation, sweetened,
original and flavored soy milk, with respect to fortification, regular,
enriched, and blended soy milk (Liu 2004).
Several methods were tested for their efficacy in removal of off flavor or
beany flavor. Some of the widely accepted methods in order to remove or
deodorize the beany flavor of soy milk are: vacuum treatment at high
temperature which results in stripping off of most volatile compounds (short
chain fatty acids, sterols, sulphur compounds etc.), leading to a better
acceptable product to the consumers, Cornell hot grinding method where soaked
soybeans were ground with boiling water or steam to obtain a slurry at a temperature
of 80 °C, the slurry was then kept at this temperature for 10 min in
order to inactivate lipoxygenase, Illinois pre-blanching method (Fig. 2) where soaked soybeans were blanched in boiling water to
inactivate lipoxygenase. Apart from these methods, alkaline soaking, use of
defatted flour, soy protein isolates and concentrates have reduced beany flavor
to some extent.
[…]
The consumption of
sesame milk can overcome the limitations associated with soy milk consumption
such as presence of flatulence causing factors, prevalence of allergies towards
soy proteins and beany or off flavor (Zahra et al. 2014). Sesame milk is commercially
available under the brand name Ecomil (Spain), Vegemil (South Korea)
etc.
[…]
Soy products are
gaining popularity as economical source of quality protein and their positive
effects on health but presence of disagreeable or beany or unpleasant flavor
needs to be eliminated or reduced in order to increase the acceptability of
products in terms of taste and flavor (Friedman and Brandon 2001). The two main reasons responsible
for off flavor are: presence of unsaturated fatty acids and the presence of
lipoxygenases (Maestri et al. 2000).
Substantial efforts have been made by several researchers in exploring
technologies and processes to eliminate beany flavor (Chiba et al. 1979;
Farkas and Goldblith 1962;
Fujimaki et al. 1965; Kon
et al. 1970;
Nelson et al. 1976;
Wilkens et al. 1967)
but, this area still needs a consideration with further exploration by the use
of newer and advanced technologies. Commonly practiced approaches to solve this problem are: inactivation
of enzymes, removal of off-flavours by deodourization and masking of
off-flavour by addition of artificial or natural flavourings
(Table 2). Lipoxidases catalyze the formation of nonvolatile
hydroperoxides from unsaturated fatty acids which, in turn, decompose into
medium-chain aldehydes and alcohols such as n-hexanal and n-hexanol
and are associated with beany or off flavor.
[…]
Thereafter,
organoleptic testing was carried out and a significant reduction in green beany
flavor was observed (Chiba et al. 1979). US
patent 4744524 issued on 17 May, 1988 described the equipment used to produce
soy milk with no beany flavor and bitter taste of traditionally processed soy
milk.
[…]
Further US patent 7258889 B2, describes a method
of preparing bean-less flavor soy milk using carbon dioxide in a state of
sublimation. The process did not involve thermal and
chemical treatment and comprised of various stages, holding soybeans with
deaerated water under an atmosphere of carbon dioxide for a combination of time
and temperature effective to allow soaking and swelling of soybeans, washing of
soaked and swollen soybeans with water to remove oligosaccharides and ripening
enzymes (as they are water soluble and gets dissolved in water used for
soaking), grinding of washed soybeans in an atmosphere of carbon dioxide by
bubbling in carbon dioxide in a sublimed state (−78 °C at atmospheric
pressure) to form a slurry followed by filtration of slurry to obtain soy milk.
The product obtained had high protein yields as process did not involve
denaturation due to thermal treatment and no beany or bitter flavor
(Alejandro 2007). The
advantages of this process are: little resident time, continuous process and
soft process conditions. The product need not to be homogenized as the soy milk
obtained was highly stable. It
is a well known fact that the modification of traditional processing method by
introducing steps like roasting, blanching and soaking in alkaline conditions
have been known to reduce beany flavor in legume based milk and hence, improved
the acceptability of the product. Addition of flavorings and sugar has been also found to
increase the overall acceptability of plant-based milk. Blending of legume milk with
cereal milk and nut milk have also helped in improving quality and wider
acceptability of plant-based milk.
[…]
Sprouting of
soybean increases protein content and also reduces fat, trypsin inhibitor and
phytic acid whose reduction otherwise requires intense heat treatment or
methods like ultrafiltration [.] The results inferred that apart from improved
nutritional profiles soy
milk from sprouted beans had higher soy milk index, good colour characteristics
and high sensory acceptability due to absence of beany flavour and odour.”
Conclusion: The results of
the survey confirm the hypothesis of the survey. The majority of participants indicated
that they do like the characteristic taste of soy milk which is typically more
pronounced in traditionally made, i.e. freshly made soy milk without added
flavorings.
References
Lawrence, S.
E.; Lopetcharat, K.; Drake, M. A. (2016): Preference Mapping of Soymilk with
Different U.S. Consumers. In Journal of food science 81 (2),
S463-76. DOI: 10.1111/1750-3841.13182.
Sethi, Swati;
Tyagi, S. K.; Anurag, Rahul K. (2016): Plant-based milk alternatives an
emerging segment of functional beverages: a review. In Journal of food science
and technology 53 (9), pp. 3408–3423. DOI:
10.1007/s13197-016-2328-3.
Verduci,
Elvira; D'Elios, Sofia; Cerrato, Lucia; Comberiati, Pasquale; Calvani, Mauro; Palazzo,
Samuele et al. (2019): Cow's Milk Substitutes for Children: Nutritional
Aspects of Milk from Different Mammalian Species, Special Formula and
Plant-Based Beverages. In Nutrients 11 (8). DOI:
10.3390/nu11081739.