🍎 Total extract in fruit and vegetable products — refractometric, pycnometric and areometric methods, PN-A-75101-02

Food chemistry PN-A-75101-02

Overview

WHAT THE STANDARD COVERS. The “Scope” field of the PKN catalogue card, in full: “Three kinds of methods are established: refractometric, pycnometric and areometric. The refractometric method consists in measuring the refractive index of the solution with a refractometer and conversion tables, or in reading the extract content directly on the refractometer. The pycnometric method consists in measuring the density of the solution with a pycnometer and converting it using tables. The areometric method consists in measuring the density of the solution with an areometer and converting it using tables, or reading it directly on the areometer. The standard contains 2 annexes with 2 conversion tables”. On the card the Polish word for “pycnometric method” is written without a space (“Metodapiknometryczna”). The card states “Adopts: ISO 2173:1978 [IDT]”, i.e. the standard is the Polish edition of the international standard ISO 2173 of 1978.

STATUS (PKN cards as of 06.11.2026). The card of PN-A-75101-02:1990 (Polish version) has the header “Withdrawn and replaced by PN-EN 12143:2000 - Polish version”: publication 24-05-1990, “Withdrawal date: 02-12-2011”, 7 pages, Food, Agriculture and Forestry Sector, KT 38 Fruit and Vegetable Products, ICS 67.080.01, “Replaces: PN-A-75101:1971 - Polish version”, “Additional elements: PN-A-75101-02:1990/Az1:2002”. The amendment PN-A-75101-02:1990/Az1:2002 (Polish version) — according to its card an additional element with the header “Withdrawn”: publication 18-12-2002, “Withdrawal date: 02-12-2011”, 1 page, KT 38; the “Scope” field, in full: “The wording of point a) of clause 1 of the standard PN-90/A-75101.02 Fruit and vegetable products. Preparation of samples and methods of physicochemical testing. Determination of total extract content was changed”. The card does not say what point a) of clause 1 concerns. SUCCESSOR. The card of PN-EN 12143:2000 (Polish version) “Fruit and vegetable juices -- Estimation of soluble solids content -- Refractometric method” has the header “Withdrawn”: publication 11-01-2000, “Withdrawal date: 24-04-2024”, 12 pages, KT 38, ICS 67.160.20, “Adopts: EN 12143:1996 [IDT]”, “Replaces: PN-A-75101-02:1990 - Polish version”; it has no “Replaced by” field. Its “Scope” field, in full: “A method is presented for determining the soluble solids content of fruit and vegetable juices by measuring the refractive index of the product analysed and reading it in percent by mass of sucrose on the sugar scale of the refractometer. For citrus fruit juices, the way of performing the so-called “acidity correction” and the values of temperature corrections for refractometrically determined substances are given. Detailed data on interlaboratory tests of repeatability and reproducibility of the method using fruit juices and concentrated juices are also given”. The chain of cards thus ends at a withdrawn standard with no successor. What this changes for the result: the successor covers only fruit and vegetable juices (not jams, purées or other products) and only the refractometric method, and gives the result in percent by mass of sucrose read on the sugar scale of the refractometer; for products other than juices PKN currently names no standard, so laboratories continue to cite PN-A-75101-02. PN-EN 12143 has a separate entry in the Knowledge Base.

LEGISLATION — TOTAL EXTRACT THRESHOLDS IN JAMS AND SIMILAR PRODUCTS. Regulation of the Minister of Agriculture and Rural Development of 29 July 2003 on detailed commercial quality requirements for jams, conserves, jellies, marmalades, plum butter and sweetened chestnut purée (Journal of Laws No 143, item 1398), amended in 2004, 2017, 2020, 2022 and 2025 (we read § 2 of the original text and all five amending acts; the Sejm register of acts contains no announcement of a consolidated text), § 2(1) as worded from 14 June 2026 (Journal of Laws 2025 item 991): “Jam, extra jam, conserves, extra conserves, jelly, extra jelly, citrus fruit marmalade, jelly marmalade, hard marmalade from fruit other than citrus fruit and sweetened chestnut purée contain not less than 60 % total extract, determined refractometrically.” § 2(2) (2003 text without point 1, repealed in 2017): soft marmalade from fruit other than citrus fruit — not less than 57 %, plum butter — not less than 54 % total extract determined refractometrically. Exceptions: paragraphs 1 and 2 do not apply to products with a lower extract content in which sugars have been wholly or partly replaced by sweeteners or whose name is accompanied by the nutrition claim “reduced sugar” (§ 2(3) as worded in 2020 and 2025); the 54 % threshold does not apply to plum butter with the claim “no added sugars” (§ 2(4), added in 2022). The 2025 regulation transposes Directive (EU) 2024/1438, which in Annex I to Directive 2001/113/EC sets the same minimum — “at least 60 % total extract determined by the refractometric method” — and repeals Article 2(4) of Directive 2001/113/EC, which required the label to show the “total sugar content” as the value indicated by the refractometer in the finished product at 20 °C, with a tolerance of ± 3 refractometric degrees. Member States apply the new provisions from 14 June 2026; products placed on the market or labelled earlier may remain on the market until stocks are exhausted (Articles 5 and 6 of Directive 2024/1438; § 2 of the 2025 regulation). Neither the regulation nor the directive names a standard — they only require the extract to be determined refractometrically.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database from the production server of 02.11.2026, read on 06.11.2026). All notations of number 75101 with sheet 02 in the reference document field: 8 entries at 8 Polish laboratories (AB 079, AB 381, AB 444, AB 452, AB 704, AB 705, AB 775, AB 1095); there are no Czech laboratories with this standard in the copy. Notations: “PN-A-75101-02:1990” (AB 079, AB 452, AB 1095), “PN-90/A-75101/02” (AB 444, AB 705, AB 775), “PN-90/A-75101.02” (AB 381) and “PN-90/A-75101-02” (AB 704). The amendment Az1:2002 is added by all 8 laboratories, point 2 of the standard by four (AB 079, AB 381, AB 705, AB 775). The “Laboratories” tab recognises all these notations and shows the same 8 laboratories (the same query as the site’s search engine, run on the database copy on 06.11.2026). Current PCA scope documents of these 8 laboratories (read on 06.11.2026, issues from 30.10.2025 to 19.10.2026): each of the 8 entries stands in the valid issue with the same range as in the copy; these documents contain no suspension footnote.

WHAT THE LABORATORIES TEST (complete entries from the PCA documents). All 8 entries are “Total extract content” (at AB 452 “Total extract”) with the technique “Refractometric method” — the pycnometric and areometric methods of this standard do not appear in any scope. Subject: fruit and vegetable products (AB 444, AB 452, AB 705, AB 775, AB 1095), fruit-and-vegetable products (AB 079, AB 704), at AB 381 also fruit and vegetables and vegetable-and-meat products. Ranges: AB 079 — (4,0–40,0) % (m/m), AB 381 — (1,0–80) %, AB 444 — (1–85) %, AB 452 — (0,5–95,0) %, AB 704 — (5,0–70,0) %, AB 705 — (3,0–75,0) %, AB 775 — (4,0–75,0) %, AB 1095 — (1,0–85) %. Next to this standard: AB 452 also has, in the same place of its scope, “Soluble solids content” according to PN-EN 12143:2000, (0,2–95) %, by the refractometric method; AB 079, AB 452 and AB 704 determine the total extract of soft drinks according to PN-A-79033 (a separate entry in the Knowledge Base); AB 313 determines the total extract of products, juices, nectars, drinks and syrups refractometrically according to the in-house procedure PB-PAZ/FS-13, (0,2–64) °Bx (%).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — the method: the regulation speaks of extract “determined refractometrically”, while the standard has three methods; a pycnometric or areometric result is a result according to the same standard, but not the one the regulation asks for. It is worth stating the point of the standard or the name of the method in the test report, because “PN-A-75101-02” alone does not settle it. Second — the laboratory’s range: the thresholds in the regulation are 54, 57 and 60 %, while AB 079 has a range up to 40,0 % (m/m); a result for a jam or plum butter cannot be reported within the scope of accreditation by such a laboratory. Third — the exceptions in the regulation: a result below 60 % does not by itself mean non-conformity if the product is sweetened with sweeteners or carries the claim “reduced sugar”, and for plum butter — “no added sugars”. Fourth — the wording of the regulation: the 60 % threshold already stood in § 2(1) as worded in 2017; the 2025 amendment (from 14 June 2026) changes the product names (“marmalade” → “citrus fruit marmalade”) and the condition of the exception, and products manufactured and placed on the market earlier in accordance with the previous provisions may remain on the market until stocks are exhausted — when assessing, one needs to know which wording applies to the sample. Fifth — the old label: the former obligation to state the “total sugar content” read by a refractometer (with a tolerance of ± 3 degrees) has been repealed — comparing the result with such a declaration on a new label has no basis in the legislation.

WHAT WE DO NOT GIVE. We did not have the text of the standard or of the amendment Az1:2002 — PKN makes them available for a fee. We do not give sample preparation (dilution, homogenisation, filtration), the measuring temperature and temperature correction, requirements for the refractometer, pycnometer and areometer, the conversion tables from the annexes or precision. We did not read the text of ISO 2173:1978; nor did we check whether the newer edition of ISO 2173 differs from it.

Method principle

According to the card of the standard: in the refractometric method the refractive index of the solution is measured with a refractometer and converted to the extract content using tables, or the extract content is read directly on the refractometer scale; in the pycnometric and areometric methods the density of the solution is measured (with a pycnometer or an areometer) and converted using tables, and with an areometer it may also be read directly. Result in percent. We DO NOT GIVE the working conditions — we did not have the text of the standard.

Applications

• Fruit and vegetable products (title of the standard); in accreditation scopes also fruit and vegetables and vegetable-and-meat products (AB 381)
• Checking commercial quality thresholds: at least 60 % total extract determined refractometrically in jam, conserves, jelly, citrus fruit marmalade and sweetened chestnut purée, 57 % in soft marmalade from fruit other than citrus fruit, 54 % in plum butter (Regulation of the Minister of Agriculture and Rural Development of 29.07.2003, § 2)
• In accreditation scopes: 8 Polish laboratories, refractometric method only, ranges from 0,5 to 95,0 %

Key parameters

Standard

Standard number

PN-A-75101-02:1990 (Polish version) with amendment PN-A-75101-02:1990/Az1:2002

Title (PL)

Przetwory owocowe i warzywne — Przygotowanie próbek i metody badań fizykochemicznych — Oznaczanie zawartości ekstraktu ogólnego

Title (EN)

Fruit and vegetable products — Preparation of samples and methods of physicochemical testing — Determination of total extract content

Step-by-step procedure

1. Status of the document and choice of method

   PKN card: standard withdrawn 02-12-2011, replaced by PN-EN 12143:2000, which was also withdrawn on 24-04-2024, with no successor named on its card (status of the cards as of 06.11.2026). When the result is to be used for an assessment under the jam regulation — the refractometric method, because the regulation speaks of extract “determined refractometrically”.

2. Sample preparation

   We DO NOT GIVE the preparation — we did not have the text of the standard.

3. Measurement

   Refractometrically: refractive index of the solution and conversion using the table, or direct reading of the extract content; pycnometrically or areometrically: density of the solution and conversion using the table (from the card).

4. Result and assessment

   Total extract content in percent, with the name of the method. Assessment against the thresholds of 60, 57 or 54 % (Regulation of the Minister of Agriculture and Rural Development of 29.07.2003, § 2) — taking into account the exceptions for products with sweeteners and with the claims “reduced sugar” or “no added sugars” (plum butter) and the laboratory’s scope of accreditation.

Required equipment and apparatus

Health and safety (OHS)

• TECHNICAL NOTE: the regulation requires extract “determined refractometrically” — a result by the pycnometric or areometric method of the same standard does not confirm this requirement
• TECHNICAL NOTE: the laboratory’s range must cover the threshold — with a range up to 40 % (AB 079) a result for jam or plum butter is not reported within the scope of accreditation

Frequently asked questions