GB/T 20886.1-2021 PDF English
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Quality requirements for yeast products -- Part 1:Yeast for food processing
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GB/T 20886.1-2021: PDF in English (GBT 20886.1-2021) GB/T 20886.1-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 67.040
CCS X 69
Replacing GB/T 20886-2007
Quality requirements for yeast products - Part 1.Yeast for
food processing
ISSUED ON. DECEMBER 31, 2021
IMPLEMENTED ON. JULY 01, 2022
Issued by. State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword... 3
Introduction... 4
1 Scope... 5
2 Normative references... 5
3 Terms and definitions... 6
4 Product classification... 8
5 Requirements... 9
6 Test methods... 11
7 Test rules... 12
8 Marking, packaging, transportation and storage... 13
Appendix A (Normative) Determination of fermentation activities... 15
Appendix B (Normative) Determination of alcoholic rate from fermentation starch. 20
Appendix C (Normative) Determination of acidity... 23
Appendix D (Normative) Determination of cell viability... 25
Appendix E (Normative) Conversion table of alcohol-water solution temperature and
alcohol (ethanol) content... 27
Appendix F (Normative) Determination of starch content in corn flour... 31
Quality requirements for yeast products - Part 1.Yeast for
food processing
1 Scope
This document specifies the terms and definitions, product classification, requirements,
test methods, inspection rules and marking, packaging, transportation and storage of
yeast for food processing.
This document applies to the production, inspection and sale of yeast for food
processing, and does not apply to yeast produced for self-use.
2 Normative references
The following documents are referred to in the text in such a way that some or all of
their content constitutes requirements of this document. For dated references, only the
version corresponding to that date is applicable to this document; for undated references,
the latest version (including all amendments) is applicable to this document.
GB/T 191, Packaging - Pictorial marking for handling of goods
GB/T 317, White granulated sugar
GB/T 601, Chemical reagent - Preparations of reference titration solutions
GB/T 602, Chemical reagent - Preparations of standard solutions for impurity
GB/T 603, Chemical reagent - Preparations of reagent solutions for use in test
methods
GB/T 1355, Wheat flour
GB 4789.15-2016, National food safety standard - Food microbiological
examination. Enumeration of moulds and yeasts
GB 5009.3-2016, National Food Safety Standard - Determination of Moisture
Content in Foods
GB 5009.4, National food safety standard- Determination of ash in foods
GB 5009.5-2016, National food safety standard - Determination of protein in foods
6 Test methods
6.1 General requirements
The water used in this method, unless otherwise specified, shall comply with the
requirements for Grade-III water in GB/T 6682-2008; all reagents used, unless
otherwise specified, are analytical reagents. The standard titration solution, the standard
solutions, preparations and products for impurity determination, which are used in the
analysis, shall be all prepared in accordance with the provisions of GB/T 601, GB/T
602, and GB/T 603, when no other requirements are specified. The solution used in the
test, if not indicated which solvent is used, refers to aqueous solution.
6.2 Sensory requirements
Take an appropriate amount of sample; put it in a colorless, clean, dry glass (or white
porcelain plate); place it in a bright place; observe its form and color with the naked
eye under natural light; smell its odor; check whether there are impurities visible with
normal vision.
6.3 Fermentation activities
Determine according to Appendix A.
6.4 Alcoholic rate from fermentation starch
Determine according to Appendix B.
6.5 Moisture
Determine according to the “direct drying method” in GB 5009.3-2016.
6.6 Acidity
Determine according to Appendix C.
6.7 Cell viability
Determine according to Appendix D.
6.8 Protein
Determine according to method I of GB 5009.5-2016, taking the conversion coefficient
F of 6.25.
6.9 Total ash
Determine according to GB 5009.4.
6.10 Viable count
Determine according to the yeast counting method in GB 4789.15-2016.
7 Test rules
7.1 Batching
Products of the same raw materials, the same formula, the same process, which are
continuously produced on the same production line and are of uniform quality are one
batch.
7.2 Sampling
7.2.1 Products are sampled by batch. When the batch is not more than 600 pieces,
samples are taken from no less than 3 packages; when the batch is more than 600 pieces,
samples are taken from no less than 0.5% of the packages. The total amount of each
sample is not less than three times the test quantity.
7.2.2 For barreled products, samples shall be taken from 10 cm below the surface. The
sampler shall be clean and dry.
7.2.3 Take two samples, seal them, and mark the sample information. One is sent for
inspection, and the other is sealed and kept for half a month for future reference. When
conducting microbiological tests, the sampler and glass bottle shall be sterilized in
advance (the sample shall not contact the bottle mouth). When the total amount of
samples is less than 200 g, the sampling ratio shall be appropriately increased.
7.3 Exit-factory inspection
7.3.1 Product shall be inspected batch by batch according to the provisions of this
document before leaving the factory. Products can only leave the factory after the
inspection meets the requirements of this document.
7.3.2 Exit-factory inspection items.
-- Baker’s yeast. sensory, fermentation activities, and moisture.
-- Brewing yeast. sensory, alcoholic rate from fermentation starch, and moisture.
-- Active edible yeast. sensory, protein, moisture, and viable count.
-- Inactive edible yeast. sensory, protein, and moisture.
7.4 Type inspection
7.4.1 Type inspection items. all items specified in this document.
7.4.2 In general, type inspection shall be carried out at least once a year. Type inspection
shall also be carried out in any of the following situations.
a) When there are major changes in raw and auxiliary materials;
b) When there are changes on critical processes or equipment;
c) When the new product is trial-manufactured, or the normal production product
is stopped for three months and resumed;
d) When the delivery inspection is significantly different from the previous type
inspection result;
e) When the national supervision and institution carries out a spot inspection
according to relevant regulations.
7.5 Determination rules
7.5.1 When all inspection items of the sampled products meet the requirements,
determine that the batch of products conforms to this document.
7.5.2 If one or two of the inspection items do not meet the requirements, double the
number of samples shall be taken from the same batch of products for re-inspection,
and the re-inspection results shall prevail; if one item still does not meet the
requirements, the batch of products shall be judged to be non-compliant with this
document. If there are three or more non-compliance indicators with requirements in
the inspection results, determine that the batch of products does not comply with this
document.
8 Marking, packaging, transportation and storage
8.1 Marking
8.1.1 When labels are used on sales packages, the product classification shall also be
indicated.
8.1.2 The pictorial marking for handling of goods shall comply with the provisions of
GB/T 191.
8.2 Packaging
Packaging containers shall be clean and undamaged and shall comply with relevant
national regulations.
8.3 Transportation
The means of transport shall be clean. Products shall not be mixed or transported with
toxic, harmful, corrosive or odorous items, and shall be kept away from moisture,
C – 1 000 mL glass measuring cylinder;
D – constant-temperature water bath.
Figure A.1 – Device for determination of fermentation activities
A.3.3 Constant-temperature water bath. temperature control accuracy ±0.2 ℃.
A.3.4 Balance. sensitivity 0.01 g.
A.3.5 Dough mixer.
A.3.6 Thermometer. graduation value 0.1 ℃.
A.3.7 Constant temperature box.
A.3.8 Vacuum pump.
A.3.9 Buchner funnel.
A.3.10 Filter bottle.
A.3.11 Medium-speed qualitative filter paper.
A.4 Test procedure
A.4.1 Fresh yeast and cream yeast
A.4.1.1 Sample processing
A.4.1.1.1 Cream yeast processing
Place two layers of medium-speed filter paper in the Buchner funnel; turn on the
vacuum pump; add a small amount of water to make the filter paper and the bottom of
the funnel stick together. Use a measuring cylinder to measure about 50 mL of cream
yeast; pour it into the Buchner funnel; filter for 5 minutes; add about 50 mL of deionized
water to the Buchner funnel; continue to filter for 25 minutes until there is no liquid
dripping from the bottom of the funnel. Take it out for later use.
A.4.1.1.2 Fresh yeast in block, granular or powdered form can be tested directly.
A.4.1.2 Dough preparation
A.4.1.2.1 Dough containing no sugar (low-sugar yeast)
Weigh 4.0 g of sodium chloride; add about 145 mL of water to dissolve it to make a salt
water solution (hereinafter referred to as salt water). Weigh 280.0 g of special grade-II
wheat flour; pour it into the dough mixer. Weigh 6.0 g of fresh yeast sample (the sample,
if refrigerated, shall be placed at 30 ℃ for 1 h in advance) into a 50 mL small beaker;
use a small amount of the above salt water to dissolve the fresh yeast; pour the dissolved
fresh yeast into the dough mixer; use a small amount of salt water to wash the small
beaker twice; pour the washing liquid and the remaining salt water into the dough mixer
together; mix and stir for 5 minutes. The dough temperature shall be 30 ℃ ± 0.2 ℃.
A.4.1.2.2 Dough containing 16% sugar (high-sugar yeast)
Weigh 2.80 g of sodium chloride and 44.8 g of white granulated sugar; add about 125
mL of water to dissolve, and make it the sugar-and-salt-water. Weigh 280.0 g of special
grade-II wheat flour; pour it into the dough mixer. Weigh 9.0 g of fresh yeast sample
(the sample, if refrigerated, shall be placed at 30 ℃ for 1 h in advance) into a 50 mL
small beaker; use a small amount of the above sugar-and-salt-water to dissolve the fresh
yeast; pour the dissolved fresh yeast into the dough mixer; use a small amount of sugar-
and-salt-water to wash the small beaker twice; pour the washing liquid and the
remaining sugar-and-salt-water into the dough mixer together; mix and stir for 5
minutes. The dough temperature shall be 30 ℃ ± 0.2 ℃.
Note. The content of each component can be increased or decreased proportionally
according to the volume of the fermentation chamber of different equipment;
the dough can also be cut into small doughs and placed in the fermentation
chamber for testing of fermentation activities, and the results need to be
converted in inverse proportion.
A.4.1.3 Determination
A.4.1.3.1 Method I (Arbitration method)
Place the dough in the instrument's test container and place it into the fermentation
instrument (A.3.1) vitality chamber. The fermentation temperature is 30 ℃ ± 0.5 ℃.
Adjust the recorder to zero and close the air release hole. Start timing from the 8th
minute from kneading the dough to the time the dough is placed in the instrument.
Record the amount of carbon dioxide gas produced by the dough in the first hour, which
is the fermentation activities of the yeast.
A.4.1.3.2 Method II
The measuring device is shown in Figure A.1.Put the prepared dough into bottle A
immediately; place bottle A into a constant temperature water bath at 30 ℃ ± 0.5 ℃;
connect bottle B (bottle B contains 2 000 mL of drainage liquid). Start timing from the
8th minute from kneading the dough to putting the dough into bottle A. Record the
drainage volume in the first hour, which is the amount of carbon dioxide gas produced
by the dough; record it as the fermentation activities of the yeast.
Note. If the content of each component is increased or decreased proportionally, the
gas production per hour needs to be converted in inverse proportion; for
example. if each component in the test is one tenth of the component shown in
Appendix B
(Normative)
Determination of alcoholic rate from fermentation starch
B.1 Reagents and materials
B.1.1 Yellow corn flour or white corn flour.
B.1.2 Sucrose solution. 20 g/L.
B.1.3 α-amylase.
B.1.4 Glucoamylase.
B.1.5 Defoaming agent. edible oil.
B.1.6 Sulfuric acid solution. 10% (volume fraction).
B.1.7 Sodium hydroxide solution. 4 mol/L.
B.2 Instruments and apparatuses
B.2.1 High pressure steam sterilizer.
B.2.2 Erlenmeyer flask. 500 mL.
B.2.3 Constant temperature box. temperature control accuracy ±0.5 ℃.
B.2.4 Precision alcohol meter. accuracy 0.2% (volume fraction).
B.2.5 Volumetric flask. 100 mL.
B.2.6 Distillation flask. 1 000 mL.
B.2.7 Electronic balance. sensitivity 0.1 mg.
B.3 Analysis steps
B.3.1 Preparation of yeast activation solution
Weigh 1.0 g (accurate to 0.000 1 g) of brewing yeast or instant dry yeast; add 16 mL of
sucrose solution; shake well; place in a 32 °C constant temperature box for activation
for 1 h; set aside for later use.
B.3.2 Liquefaction
Weigh 50 g of corn starch that has passed through a 0.425 mm sieve; put it in a 500 mL
Erlenmeyer flask; add α-amylase (80 U ~ 100 U) per gram of corn starch; add 175 mL
of hot water; stir well. Adjust the pH to 6.0 ~ 6.5; heat on an electric stove while stirring.
Stop heating after boiling; use tap water to rinse the corn paste on the wall of the
Erlenmeyer flask, so that the total mass of the contents is 250 g. Put it in a 70 ℃ ~ 85 ℃
constant temperature box to liquefy for 30 min.
B.3.3 Cooking
Seal the Erlenmeyer flask containing the liquefied corn paste with cotton plugs and
waterproof paper; put it into a high-pressure steam sterilizer; maintain the pressure at
0.1 MPa for 1 hour. Take it out and cool it to 60 ℃.
B.3.4 Saccharification
Use sulfuric acid solution (B.1.6) to adjust the pH of the cooking liquid to about 4.5.
Add glucoamylase (150 U ~ 200 U) per gram of corn flour and stir well. Place it in a
60 ℃ constant temperature box and saccharify for 60 minutes. Cool to 30 ℃ ~ 35 ℃.
B.3.5 Fermentation
Add 2.0 mL of yeast activation solution (see B.3.1) to each flask; shake well; cover.
Place the Erlenmeyer flask in a 32 ℃ constant temperature box and ferment for 65
hours. When measuring high temperature resistant dry yeast, place the Erlenmeyer flask
in a 40 ℃ constant temperature box and ferment for 65 hours.
B.3.6 Distillation
Use sodium hydroxide solution to neutralize the fermentation mash to pH 6.0 ~ 7.0;
pour all the fermentation mash into a 1 000 mL distillation flask. Use 100 mL of water
to rinse the Erlenmeyer flask several times; pour the washings into the distillation flask;
add 1 ~ 2 drops of defoaming agent; distill. Use a 100 mL volumetric flask (with an ice-
water bath) to receive the distillate. When distilled to 95 mL, stop distillation and
remove it. After the temperature is balanced to room temperature, dilute to 100 mL.
B.3.7 Measuring alcohol content
Pour all the distillate after volume adjustment into a clean, dry 100 mL measuring
cylinder; let it stand for a few minutes; after the bubbles in the wine disappear, put it
into a clean and dry precision alcohol meter. After standing, observe the scale value at
the tangent point of the meniscus horizontally; at the same time, insert a thermometer
to record the temperature. According to the measured alcohol content and temperature,
convert it to the alcohol content at 20 ℃ according to Appendix E.
B.4 Test data processing
Calculate the alcoholic rate from fermentation starch according to Formula (B.1) and
express its value in %.
Appendix D
(Normative)
Determination of cell viability
D.1 Method summary
Living yeast cells can reduce the dye that enters the cells without being stained, and the
number of living cells in the yeast can be calculated and quantified.
D.2 Solution
D.2.1 Sterile normal saline.
D.2.2 Methylene blue staining solution. Weigh 0.025 g of methylene blue, 0.042 g of
potassium chloride, 0.048 g of calcium chloride hexahydrate, 0.02 g of sodium
bicarbonate and 1.0 g of glucose; mix them; add sterile normal saline to fix the volume
to 100 mL.
D.3 Instruments and apparatuses
D.3.1 Microscope.
D.3.2 Blood counting chamber. 16×25.
D.3.3 Electronic balance. sensitivity 0.1 mg.
D.3.4 Constant-temperature water bath. temperature control accuracy ±0.5℃.
D.4 Yeast activation
Weigh 0.1 g of instant dry yeast or 0.3 g of fresh yeast (accurate to 0.000 1 g; if the
sample has been refrigerated, place it at 30 °C for 1 h in advance); add it to 20 mL of
sterile normal saline (38 °C ~ 40 °C); activate it in a constant temperature water bath at
32 °C for 1 h.
D.5 Determination of cell viability
Vortex the activation solution evenly; aspirate 0.1 mL of yeast activation solution; add
0.9 mL of staining solution; shake well; stain at room temperature for 10 minutes;
immediately count using a blood counting chamber under a microscope.
D.6 Analysis steps
D.6.1 Place the coverslip on the blood counting chamber, making sure it covers the
blood counting chamber tightly; draw 0.1 mL of the dyed solution; put 0.02 mL of the
dyed solution into the blood counting chamber from the junction of the blood cell
counting plate and the cover glass (put 0.02 mL from the top of the graduated pipette
Appendix F
(Normative)
Determination of starch content in corn flour
F.1 Principle
The starch in corn flour is hydrolyzed into reducing monosaccharides by acid. After the
hydrolysate is treated to remove impurities, determine the reducing sugar content by
direct titration and then multiply by a coefficient to convert it into starch content.
F.2 Reagents and solutions
F.2.1 Hydrochloric acid.
F.2.2 Hydrochloric acid solution [c(HCl) = 1.5 mol/L]. prepared according to GB/T 601.
F.2.3 Sodium hydroxide solution (400 g/L). Weigh 40 g of sodium hydroxide; dissolve
it in water; fix the volume to 100 mL.
F.2.4 Lead acetate solution (200 g/L). Weigh 20 g of lead acetate; dissolve it in water;
fix the volume to 100 mL.
F.2.5 Sodium sulfate solution (100 g/L). Weigh 10 g of sodium sulfate; dissolve it in
water; fix the volume to 100 mL.
F.2.6 Alkaline cupric tartrate solution A. Weigh 15 g of copper sulfate (CuSO4·5H2O)
and 0.5 g of methylene blue; add water to dissolve; fix the volume to 1 000 mL; store
it in a brown glass bottle.
F.2.7 Alkaline cupric tartrate solution B. Weigh 50 g of sodium potassium tartrate and
75 g of sodium hydroxide; dissolve in water; then, add 4 g of potassium ferrocyanide.
After it is completely dissolved, add water to dilute and fix the volume to 1 000 mL;
store in a rubber-stoppered glass bottle.
F.2.8 Glucose standard solution (1 g/L). Weigh 1.000 g of anhydrous glucose that has
been dried to constant weight at 98 ℃ ~ 100 ℃; dissolve it in 500 mL of water; add 5
mL of hydrochloric acid (F.2.1); add water to dilute, and fix the volume to 1 000 mL.
F.2.9 Methyl red indicator. Weigh 0.2 g of methyl red; dissolve it in 95% ethanol; fix
the volume to 100 mL.
F.3 Instruments and apparatuses
F.3.1 Water bath. temperature 0 ℃ ~ 100 ℃.
F.3.2 Erlenmeyer flask.
...... Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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