ESTIMATION OF THE TOTAL SOLIDS IN NATURAL JUICE AND NECTAR Dr. María José Frutos Fernández Agro-Food Technology Department Miguel Hernández University Orihuela (Alicante) Spain WORKSHOP ON ESTIMATION OF NATURAL JUICES IN NECTARS Cairo, egypt november 2014

TOTAL SOLUBLE SOLIDS (TSS) Total soluble solids (TSS) is an important index together with titratable acidity (TA) respect to juice and nectar quality. TSS refers to the total amount of soluble constituents of the juice. These are mainly sugars, with smaller amounts of organic acids, vitamins, proteins, free amino acids, essential oils and glucosides. Approximately 85% of the total soluble solids of citrus fruit are sugars STANDARD METHODS Estimation of soluble solids content. Refractometric method (UNE-EN 12143) Determination of Soluble Solids FU Analysis Federation of Fruit No. 8 (Rev. 2005) (indirect method by refractometry) _________________________________________________________________ _____

Determination of SoIFU Analysis Federation of Fruit No. 8 (Rev. 2005) (indirect method by refractometry) luble Solids General The result from a refractometer determination should be distinguished from that obtained by direct determination. Principle The dry soluble solids content of a sample is estimated from its refractive index, with reference to the refractive index of a pure sugar solution. The refractive index is proportional to the solution concentration (following the theory of Lorentz and Lorenz). In fruit juices the refractive index is therefore dependent upon sugar concentration and also upon the concentration of other soluble materials (organic acids, minerals, amino acids etc.)

Determination of soluble solids Apparatus Refractometer (Abbe type) - Scale divisions to at least 0,1% sucrose - Exact temperature control to 20 °C ± 0,5 °C - Calibration before each set of measurements, following the manufacturers' instructions Experimental procedure Sample preparation Determination Bring the sample to a temperature of ca. 20 °C (± 0,5 °C). This temperature should be checked before every measurement. The percentage sucrose content is read directly to the nearest 0,1%.

Determination of soluble solids Calculation: The content of soluble solids is usually expressed in grams of sucrose per 100 g of material. The result given is the percentage sugar according to the refractometric method. The value is read directly. In citrus juices and other juices containing high amounts of citric acid such as blackcurrant, a so- called 'acid correction' is usually made. The following addition is made to the refractometer reading: 0, ,193x - 0,0004 ⋅ x 2 where x = % total acid (pH 8,1), expressed as anhydrous citric acid (IFFJP method no. 3). The calculated values for this expression are given in Table A. Statement of result :The result is given as Soluble Solids (refr.) in g/100 g or°Brix, to one decimal place. If an acid correction has been applied, this should be indicated with the suffix «corr.»

Determination of soluble solids Table B. Relationship between °Brix (percent sucrose by weight), relative density (D 20/20 ) and total solids (kg/m 3, equivalent to g/litre) Table A: Acid Correction to the Brix value (Bx°) for high acid (Citrus) concentrates. The correction values given are added to the refractometer values (expressed in °Bx = grams of sucrose / 100 grams of sample), obtained at 20°C. ºBrixD 20/20 Total Solids (IFU Analysis No 8. Rev.2005)

JUICE RECONSTITUTION 1.°Brix Guidelines for Juice Reconstitution°Brix Guidelines for Juice Reconstitution 2.°Brix Reading of Reconstituted Juice°Brix Reading of Reconstituted Juice 3.Reconstitute a Predetermined Volume of JuiceReconstitute a Predetermined Volume of Juice 4.Reconstitute Juice from Concentrate of a known volumeReconstitute Juice from Concentrate of a known volume

MINIMUM BRIX14 LEVEL FOR RECONSTITUTED JUICE AND RECONSTITUTED PURÉE AND MINIMUM JUICE AND/OR PURÉE CONTENT FOR FRUIT NECTARS (% V/V)15 AT 20 O C From: Codex Stan 247 (2005) *It is recognized that in different countries, the Brix level may naturally differ from this value. In cases where the Brix level is consistently lower than this value, reconstituted juice of lower Brix from these countries introduced into international trade will be acceptable, provided it meets the authenticity methodology listed in the General Standard for Fruit Juices and Nectars and the level will not be bellow 10ºBrix for pineapple juice and apple juice ** ** Acid corrected as determined by method for total titratable acids in the Section on Methods of Analysis. BOTANICAL NAMEFruit’s Common name Minimum Brix level for Reconstituted Fruit Juices and Reconstituted Puree Minimum Juice and /or Purée content (% v/v) for Fruit Nectars Ananas comosus (L.) Merrill Ananas sativis, L. Schult.f. Pineapple12.8*40.0 Citrus reticulata BlancaMandarine / Tangerine 11.8**50.0

CALCULATION OF FRUIT JUICE CONTENT FORMULATION: X% fruit Nectar at Y ºBrix (100L of product). Fruit concentrate Z ºBrix. Calculation 1. Minimum % fruit juice (Directive 2012/12/EU) 2. Total soluble solids contribution 3. Concentrate equivalent (vol) required for 100 L of final product 4. Percentage of fruit juice content at standard strength.

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