4. Ash and Mineral Analysis .pdf

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9/23/24 Definition of Terms ØAsh Content ASH AND MINERALS §The inorganic residue remaining after ignition or complete oxidation of the organic matter in ANALYSIS food ØMineral content §measure of the amount of specific inorganic FST 102 component present within a food (eg. % Ca, % Na, % K, % Cl) 9/23/24 3 1 3 Importance Importance a. Nutritional labeling b. Quality assessment Ø Na is associated with hypertension ex. sardines – formation of struvite Ø Ca is needed in calcification of bones (white crystals like broken glass) Ø Fe is important component of hemoglobin that (NH4)MgPO4٠6H2O carries oxygen from lungs to other parts of the PO4 – naturally present in sea foods body Mg – present in H2O ØZn helps immune system and metabolism function NH4 – produced due to high heat or Ø Cu helps maintain healthy bones, blood vessels, from contamination nerves, and immune function h t t p s :/ / w w w.g o o g le.c o m / u r l? s a = i& u r l= h t t p s % 3 A % 2 F % 2 F w w w.n o r t h w e s t k a y a k a n g le r s.c o m % 2 F in d e x.p h p % 3 F t o p ic % 3 D 1 8 8 1 3.0 & p s ig = A O v V a w 2 _ h n X IA o g H R Ie Jx b 0 3 - h t t p s :/ / w w w.g o o g le.c o m / u r l? s a = i& u r l= h t t p s % 3 A % 2 F % 2 F w w w.n o r t h w e s t k a y a k a n g le r s.c o m % 2 F in d e x.p h p % 3 F t o p ic % 3 D 1 8 8 1 3.0 & p s ig = A O v V a w 2 _ h n X IA o g H R Ie Jx b 0 3 - h X h & u s t = 1 6 1 4 0 8 5 6 1 3 2 8 7 0 0 0 & s o u r c e = i m a g e s & c d = v f e & v e d = 0 C A 0 Q jh x q F w o T C J D c h t L H _ e 4 C F Q A A A A A d A A A A A B A I h X h & u s t = 1 6 1 4 0 8 5 6 1 3 2 8 7 0 0 0 & s o u r c e = i m a g e s & c d = v f e & v e d = 0 C A 0 Q jh x q F w o T C J D c h t L H _ e 4 C F Q A A A A A d A A A A A B A I 9/23/24 4 9/23/24 5 4 5 1  9/23/24 Importance Sample Preparation c. Microbiological quality consideration 1. Properly reduced the amount and Ø some minerals are used to minimize microbial proliferation particle size of the sample Ø increase in mineral content decreases the Aw of food 2. Pre-dry the sample if high in moisture d. food safety 3. De-fat the sample if high in fat Ø elemental analysis of toxic heavy metals Ø analysis of transition metals in lipid rich food 9/23/24 6 9/23/24 7 6 7 Methods Crucibles as sample container 1. Dry Ashing Quartz Ø use a muffle furnace capable of maintaining Ø resistant to acid and halogens at ↑T˚ but not to T˚ of 550 to 600˚C alkaline Ø minerals are converted to oxides, sulfates, Vycor® glass chlorides and silicates without flaming Ø Stable up to 900˚C Ø Fe, Se, Pb and Hg are partially volatilized Pyrex Ø Maximum temp at 500˚C Platinum Ø most inert, but too expensive h t t p s :/ / w w w.g o o g le.c o m / u r l? s a = i& u r l= h t t p s % 3 A % 2 F % 2 F w w w.in d ia m a r t.c o m % 2 F p r o d d e t a il% 2 F p la t in u m - c r u c ib le - a n d - lid - 1 2 0 8 6 1 7 7 5 6 2.h t m l& p s ig = A O v V a w 2 o Y E p v 0 h q a K R B a g X Q 3 W _ x F & u s t = 1 6 1 4 1 2 6 9 0 9 6 0 4 0 0 0 & s o u r c e = im a g e s & c d = v f e & v e d = 0 C A 0 Q jh x q F w o T C IiN 9 L z h _ u 4 C F Q A A A A A d A A A A A B A D h t t p s :/ / w w w.g o o g le.c o m / u r l? s a = i& u r l= h t t p s % 3 A % 2 F % 2 F w w w.f is h e r s c i.c o m % 2 F s h o p % 2 F p r o d u c t s % 2 F p y r e x - g o o c h - t y p e - f ilt e r in g - c r u c ib le s - lo w - f o r m - m e d iu m - 3 0 m l% 2 F 0 8 2 3 6 1 b & p s ig = A O v V a w 3 P x I3 N r Q e 4 Z 9 o d q S V 8 1 t f T & u s t = 1 6 1 4 1 2 6 9 3 5 7 0 5 0 0 0 & s o u r c e = im a g e s & c d = v f e & v e d = 0 C A 0 Q jh x q F w o T C N C 2 2 M z h _ u 4 C F Q A A A A A d A A A A A B A D h t t p s :/ / w w w.g o o g le.c o m / u r l? s a = i& u r l= h t t p s % 3 A % 2 F % 2 F w w w.s ig m a a ld r ic h.c o m % 2 F c a t a lo g % 2 F p r o d u c t % 2 F a ld r ic h % 2 F z 1 3 8 8 4 3 % 3 F la n g % 3 D n u ll% 2 6 r e g io n % 3 D n u ll& p s ig = A O v V a w 0 M f q M H V m 9/23/24 8 9/23/24 0 s Q 1 m u G a t R M R s u & u s t = 1 6 1 4 1 2 7 0 1 4 5 7 3 0 0 0 & s o u r c e = im a g e s & c d = v f e & v e d = 0 C A 0 Q jh x q F w o T C P jW z P D h _ u 4 C F Q A A A A A d A A A A A B A D h t t p s :/ / w w w.g o o g le.c o m / u r l? s a = i& u r l= h t t p s % 3 A % 2 F % 2 F w w w.a lib a b a.c o m % 2 F p r o d u c t - d e t a il% 2 F H ig h - p u r it y - 9 9 - 9 9 - O p a q u e - 9 F u s e d _ 6 0 6 5 7 3 7 3 3 8 9.h t m l& p s ig = A O v V a w 2 E V R d _ D k lt n iS R w e K h g E _ L & u s t = 1 6 1 4 1 2 7 1 4 7 2 8 1 0 0 0 & s o u r c e = im a g e s & c d = v f e & v e d = 0 C A 0 Q jh x q F w o T C M iv p L v i_ u 4 C F Q A A A A A d A A A A A B A D 8 9 2  9/23/24 Crucibles as sample container Advantages and Disadvantages Porcelain Advantages: Ø maximum temp at 1200˚C; widely used (cheap) Safe, no reagents needed, not labor intensive, many Ø not resistant to high temperature fluctuation samples can be analyzed simultaneously, the resultant Steel ash can be used for specific mineral analysis Ø Resistant to acid and base Disadvantages: Ø made up of iron, nickel and chromium which may be source Expensive initial cost of equipment, loss of volatiles of of contamination As, B, Cd, Cr, Cu, Fe, Pb, Hg, Ne, P, V and Zn; high Quartz Fiber moisture, fat and sugar samples needs pre-treatment Ø disposable, unbreakable, and can withstand temperatures up to 1,000 °C h t t p s :/ / w w w.g o o g le.c o m / u r l? s a = i& u r l= h t t p s % 3 A % 2 F % 2 F w w w.f lin n s c i.c o m % 2 F s t a in le s s - s t e e l- c r u c ib le - w it h - c o v e r - 3 0 - m l% 2 F a p 7 6 1 5 % 2 F & p s ig = A O v V a w 1 jy B V H E L n F D 2 5 e f F n Ik b h p & u s t = 1 6 1 4 1 2 6 7 6 7 5 4 1 0 0 0 & s o u r c e = im a g e s & c d = v f e & v e d = 0 C A 0 Q jh x q F w o T C M iA 2 f r g _ u 4 C F Q A A A A A d A A A A A B A D h t t p s :/ / w w w.g o o g le.c o m / u r l? s a = i& u r l= h t t p s % 3 A % 2 F % 2 F w w w.f is h e r s c i.c o m % 2 F s h o p % 2 F p r o d u c t s % 2 F 1 0 0 m l- q u a r t z - c r u c ib le - 1 6 - c s % 2 F n c 9 1 3 9 5 8 3 & p s ig = A O v V a w 0 h A R u K J u 4 R c O n E Y K w io B i- & u s t = 1 6 1 4 1 2 6 7 2 5 3 7 0 0 0 0 & s o u r c e = i m a g e s & c d = v f e & v e d = 0 C A 0 Q jh x q F w o T C I D t y J L h _ u 4 C F Q A A A A A d A A A A A B A D h t t p s :/ / w w w.g o o g le.c o m / u r l? s a = i& u r l= h t t p s % 3 A % 2 F % 2 F w w w.u t e s t.c o m.t r % 2 F e n % 2 F 3 9 1 7 4 % 2 F P o r c e la in - C r u c i b l e & p s i g = A O v V a w 0 I K B C C f g 4 0 N Y n C S K k v J R 1 i & u s t = 1 6 1 4 1 2 6 8 4 2 9 8 3 0 0 0 & s o u r c e = i m a g e s & c d = v f e & v e d = 0 C A 0 Q jh x q F w o T C N jn w Z v h _ u 4 C F Q A A A A A d A A A A A B A J 9/23/24 10 9/23/24 11 10 11 Methods Procedure 2. Wet Ashing Ø Weighed sample in flask with strong acid and oxidizing agent ØWet oxidation or wet digestion Ø Heat until organic matter is completely digested, leaving ØCommonly used prior to specific mineral analysis mineral oxides in the solution (end point clear solution) ØMinerals stay dissolved in the solution with little or no loss from volatilization due to use of low temperature Reagent combination: HNO 3/H 2SO 4 ØUtilizes acid to break down the organic matrix of the sample H 2O 2/H 2SO 4 Nitric acid – oxidant (volatile) HNO 3/HClO 4 Sulfuric acid – digestion Perchloric acid – digestion 9/23/24 12 9/23/24 13 12 13 3  9/23/24 Advantages and Disadvantages Methods Advantages: 3. Microwave Dry Ashing ØLittle or no loss of volatile minerals Used for both wet ashing and dry ashing ØRapid than dry ashing can ash samples in minutes, decreasing analysis time by as much as 97 % Disadvantages: can reach temperatures of up to 1200 °C and be programmed ØLabor intensive (constant operator attention needed) with various methods to automatically warm up and cool down ØSmall number of samples can be handled at one time 9/23/24 14 9/23/24 Free template from www.brainybetty.com 15 14 15 Methods Methods 3. Microwave Ashing ØCan be performed safely in either an open- or 3. Plasma Ashing closed-vessel microwave system - food samples are oxidized in a partial vacuum using § closed vessels can withstand higher nascent oxygen pressures up to 1,500 psi, allowing acids be ¶Nascent oxygen-free radical form of oxygen which is heated above boiling to ensure complete very reactive dissolution of hard-to-digest substances § Open-vessel digestion systems are used often for larger sample sizes (up to 10 g) and for samples that generate substantial amounts of gas as they are digested. h t t p s :/ / w w w.g o o g le.c o m / u r l? s a = i& u r l= h t t p s % 3 A % 2 F % 2 F q t e c h c o r p.c o m % 2 F p r o d u c t % 2 F q w a v e - 1 8 0 0 % 2 F & p s ig = A O v V a w 3 s M O U g N O X B E 6 A D 2 k 0 jm u v u & u s t = 1 6 1 4 1 2 7 7 3 7 0 5 2 0 0 0 & s o u r c e = im a g e s & c d = v f e & v e d = 0 C A 0 Q jh x q F w o T C K iP 0 N 7 k _ u 4 C F Q A A A A A d A A A A A B A z h t t p s :/ / w w w.g o o g le.c o m / u r l? s a = i& u r l= h t t p % 3 A % 2 F % 2 F w w w.s p e c ia t io n.n e t % 2 F D a t a b a s e % 2 F In s t r u m e n t s % 2 F M ile s t o n e - S r l% 2 F P Y R O - S A - S u lp h a t e - A s h in g - S y s t e m - % 3 B i 1 1 0 5 & p s i g = A O v V a w 3 s M O U g N O X B E 6 A D 2 k 0 jm u v u & u s t = 1 6 1 4 1 2 7 7 3 7 0 5 2 0 0 0 & s o u r c e = i m a g e s & c d = v f e & v e d = 0 C A 0 Q jh x q F w o T C K i P 0 N 7 k _ u 4 C F Q A A A A A d A A A A A B B F 9/23/24 16 9/23/24 17 16 17 4  9/23/24 Features: a. Temperature used is < 150˚C to prevent Advantages and Disadvantages volatilization of most minerals Advantage: b. Sample is placed in a vacuum glass chamber, small amount of O2 is introduced Less chance of losing trace elements by volatilization and broken down to nascent oxygen due to application EMR. Disadvantages: O2 EMR 2O Small sample capacity, expensive equipment c. The organic matter is oxidized by 2O and moisture evaporates because of elevated temperature. 9/23/24 18 9/23/24 19 18 19 Other Ash Measurement Other Ash Measurement a. Soluble and insoluble ash in water b. Ash insoluble in acid Øserves as index of fruit content of preserves and jellies Ø measure of surface contamination Ø presence of insoluble ash in the water-soluble portion is an Ø contaminants are insoluble in acid (in the form of silicates) indicator that extra fruit is added to the product Ø ↑insoluble ash in acid ↑silicate content Ø ↑insoluble ash ↑ amount of fruit Ø after dry ashing + acid, stir and filter; residue is the measure Ø After dry ashing + 10mL dH2O, stir and filter; residue is of ash insoluble in acid measured as insoluble ash 9/23/24 20 9/23/24 21 20 21 5  9/23/24 Other Ash Measurement Other ash measurement c. Alkalinity of Ash d. Sulfated Ash Ø use to measure the acid-base balance of the food Ø indication of adulteration applied mostly to sugars, syrups, and color additives Ø Acid forming elements: P, S, Cl measures the amount of residual substance not Ø Base forming elements: K, Na, Ca, & Mg volatilized when the sample is ignited in the presence Ø Minerals in fruits and vegetables are usually alkaline while in meats and of sulfuric acid cereals are acidic Ø After dry ashing + Acid solution of known concentration then titrate with Alkaline solution of the same concentration until neutralized 9/23/24 22 9/23/24 23 22 23 SPECIFIC MINERAL ANALYSIS Classification of minerals based on required dietary requirement § Determination of specific mineral content in food require the minerals to be in an aqueous solution a. Macro minerals - > 100 mg/day § Ashing must be done prior to analysis eg. Ca, K, P, Na, Mg, Cl, S § The ashing procedure must not alter the mineral b. Trace elements - < 100 mg/day concentration eg. Fe, I, Zn, Cu, Cr, Mn, Mo, F, Se, Si § Contamination must also be prevented by using deionized or ultrapure water c. Ultra trace minerals – V, Ni, Ar, B, Sn d. Toxic – Pb, Hg, Cd, Al 9/23/24 24 9/23/24 Free template from www.brainybetty.com 25 24 25 6  9/23/24 Minerals in food processing Basic considerations a. preservative (salt) a. Physicochemical properties of minerals that distinguish it b. enrichment (iron in flour) from the food matix c. fortification (Ca, Fe, Zn in breakfast cereals) i. low volatility – minerals like ash do not decompose at ↑T˚ Øsome processing methods remove minerals in food ii. capable of producing measurable changes when treated with specific chemical reagent eg. removal of bran from rice iii. unique electromagnetic spectrum acid treatment in cottage cheese removes Ca 9/23/24 Free template from www.brainybetty.com 26 9/23/24 27 26 27 Basic considerations Basic considerations b. Sample Preparation ii. Water to be used should be ultrapure water, deionized water, i. ash sample (dry, wet or low T˚ ashing) 3x distilled water; water of highest purity/ no tap water Ø wet ashing is the easiest because it would not require distilled – atomic form of elements are removed expensive treatment deionized – ions are removed Ø low T˚ is advantageous but uses expensive treatment iii. use plastic wares rather than glass wares Øthe minerals have high tendency to adhere to the walls of a glass resulting in ↑contamination 9/23/24 Free template from www.brainybetty.com 28 9/23/24 Free template from www.brainybetty.com 29 28 29 7  9/23/24 Methods Methods a. Gravimetric Analysis b. Colorimetric method Ø Target mineral is precipitated from the solution Ø Based on the change in color of a reagent when it reacts by addition of a reagent with a specific mineral in a solution Ø Formation of an insoluble complex with known Ø Can be quantified by measuring the solution’s absorbance chemical formula using a spectrometer Ø Precipitate can be filtered, dried and weighed e.g. Orthophosphate + ammonium molybdate + antimony eg. Fe3+ → Fe(OH)3 → FeO3 potassium tartrate →antimony-phosphomolybdate complex e.g. Mohr Method: (Chlorides) ØAscorbic acid is added to reduce the complex producing a NaCl + AgNO3 →AgCl(s) + NaNO3 blue color 2Ag+ (Excess)+ CrO4 2- →Ag2 CrO4(s) 9/23/24 30 9/23/24 31 30 31 Methods c. Titration method Ø The analyte is titrated with a reagent capable of forming a complex with the analyte ØAnalyte-titrant interaction is stronger than indicator-titrant interaction EDTA e.g. EDTA titration for Ca or Mg analysis Ca 2++EDTA indicator: Eriochrome Black T (EBT); Calmagite Ca 2++EBT EBT=blue changes color if bound to an ion 9/23/24 32 32 8