What is behind cereal flavour: Case studies on linking sensory and instrumental data Raija Liisa Heiniö, VTT Biotechnology, Finland ESN Conference Sensory evaluation More than just food 25 26 May 25, Madrid 1 RLH Outline of presentation Benefits of wholegrain products Formation and modification of flavour of cereal products Relating perceived flavour and flavour active chemical compounds Case studies 1. Stability of oats 2. Milling fractionation of rye: Flavour and bioactivity 3. Tailoring cereal flavour by bioprocessing 4. Enzyme aided flavour boosting 1
WHY WHOLE GRAIN? Rye and oat are consumed as whole grain Raw material for health beneficial foods Decreases risk to several diseases, e.g. diabetes, cardiovascular diseases and many cancers High fibre content, low fat content Good source of starch, valuable proteins, high vitamin and mineral content Several phytochemicals: lignans, plant sterols, alk(en)ylresorcinols (in rye), avenanthramides (in oats), phenolic acids; Most phenolic compounds bioactive & influence perceived flavour 3 RLH Consumer originated product development of cereal products Flavour & texture of cereal products must appeal to consumers and meet their expectations Desired flavour & texture to be ACTIVELY DESIGNED instead of just measuring sensory profiles of products Flavour & texture of cereal foods to be adjusted by DIFFERENT PROCESSING TECHNIQUES to produce ideal products 4 RLH 2
Formation and modification of flavour of cereal products Flavour of native grain is rather mild and bland Grain must be processed prior to use in human consumption Cereal flavour forms in processing Wheat Oat Rye Barley 5 RLH Flavour formation in cereal products What is 'cereal like' flavour? Rye like flavour = Flavour of rye bread? Oat like flavour = Flavour of oat porridge? All cereal have their characteristic flavour Oat flavour different from rye flavour Variety of grain, season and cultivation area influence flavour Oat cultivar Veli has sweeter, more oat like flavour than cv. Lisbeth 6 RLH 3
Tailoring desired flavour & texture to cereal products Mechanical milling fractionation of the grain Sourdough fermentation & baking Germination (malting) & drying Heat treatment: Extrusion, puffing in autoclave, IR roasting Enzymatic flavour boosting Fermentation & germination increase amounts of health beneficial phenolic compounds, concurrently influencing considerably perceived flavour Heat treatment important step for tailoring perceived flavour (Maillard reaction) 7 RLH Perception of flavour (odour & taste; mouthfeel) Nasal Retronasal Odour perception Taste perception 8 RLH 4
Chemistry behind flavour formation Components influencing the perceived flavour Volatile compounds Phenolic compounds Free amino acids, small peptides PERCEIVED FLAVOUR Free fatty acids, lipids Perceived flavour is influenced by 1 Flavour active compounds of grain aldehydes, alcohols, ketones, phenolic compounds 2 Flavour precursors in grain amino acids, sugars, fatty acids, phenolic compounds Sugars 9 RLH Flavour active compounds influence perceived flavour of a product, but In addition to volatile compounds, several non volatile components affect the perceived flavour Specific odour/ taste thresholds of the chemical compounds All chemical compounds are not responsible for flavour sensation Synergistic or suppressive effects of compounds Individual differences in sensitivity of odour/ flavour perception 1 RLH 5
PLS regression Relating perceived flavour and flavouractive chemical compounds by multivariate statistics Sensory assessment by descriptive profiling GC/MS quantification of e.g. volatile compounds Sitkeys Värin ruskeus 1 9 8 Rukiin maun voimakkuus 7 2 3 8 11 13 14 23 6 5 Kovuus 4 3 2 1 Paahtuneisuus Kas 141/28 Kas 141/29 Kas 141/3 Kas 141/31 7 1 18 25 17 Rapeus Makeus Kas 141/32 Kas 141/33 1 4 16 15 5 2 19 9 12 24 21 6 26 22 Huokoisuus Kitkeryys Jälkimaun voimakkuus Flavorin voimakkuus PLS regression Relating perceived flavour and flavouractive chemical compounds by multivariate statistics Perceived flavour and volatile compounds analysed separately LISBETH FREEZE DRIED.6 PC2.4.2.2.4 Limonene Cymene T Moist F Germ LISBETH 3 5 C F Bitter Isobutanal O Moist F Musty T Tough F Intense Aftertaste Butanone O Earthy F Rancid O Intense Dimethyl sulphides 2 Pentanone O Roast Isobutanol O Musty F Roast Butanal O Cereal F Cereal Pentanal Hexanal 2 Pentylfuran Methylbutanal.4.2 X expl: 65%,23% Y expl: 29%,12% VELI 3 5 C VELI FREEZE DRIED X loading Weights and Y loadings T Brittle F Sweet.2 F Nutty T Hard T Crisp.4 Impact of flavour active compounds to flavour of germinated, heat treated oat: Roasted, nutty, sweet flavour, crisp texture results when drying at 85 C LISBETH 65 95 C LISBETH 65 85 C VELI 65 85 C VELI 65 95 C PC1.6 Heiniö et al. Cereal Chem. 21 12 RLH 6
GC Olfactometry GC analysis combined with simultaneous odour perception GC Olfactometry Flavour extraction by SPME (compound specific fibres) Piece of GC Olfactometry chromatogram of a cereal product 14 RLH 7
CASE 1 Stability of oat Rancid and bitter flavour develops easily in oat during storage due to its high fat content Germination drying process can be used to adjust effectively the perceived flavour and to increase the flavour stability CASE 1 Relating perceived flavour and flavour active volatile compounds of stored oat 1.5 PC2 1..5.5 X loading Weights and Y loadings F BITTER F INTENSE O MUSTY AFTER TASTE Native 12 Germinated 6 O INTENSE Native 9 F RANCID Germinated 9 F MUSTY F NUTTY Germinated 12 Pentanal F ROASTED Native 6 n Butylfuran Pentylfuran O EARTHY O ROASTED 1 Hexanal F CEREAL Phenyl acetate 1 Pentanol O MOIST 3 Pentanone F SWEET 1 Hexanol O CEREAL Methylpropanal Germinated Heptanal Methylbutanal Dimethylsulphide 2 Heptanone Belzaldehyde F GERMLIKE Native 2 Ethylfuran 1. PC1.4.2.2.4 Heiniö et.6 al. Cereal Chem..8 22 1. 16 RLH 8
CASE 1 Stability of oat Musty, earthy odour and bitter, rancid flavour in stored, deteriorated oat; these attributes closely correlate with free fatty acids and volatile compounds related to lipid oxidation However, phenolic compounds and volatile compounds derived from protein degradation are related to favourable roasted flavour CASE 2 Milling fractionation of rye: Flavour and bioactivity In mechanical milling fractionation rye kernel is separated into fractions, each of them having their characteristic flavour Shorts 9
CASE 2 Flavour of milling fractionationated rye grain Flavour components unevenly distributed to different layers of rye grain Endosperm: Mild flavour Shorts: Rye like flavour without bitterness Bran: Strong, bitter flavour Between mild tasting innermost part and bitter tasting outer bran fraction, rye like flavour without bitterness is observed This shorts fraction contains significant amounts of health beneficial, nonvolatile phenolic compounds (phenolic acids, alk(en)ylresorcinols and lignans), which may have input to perceived flavour Heiniö R L et al. LWT 23a 19 RLH CASE 2 Flavour and bioactivity of fractionationated rye: Flavour vs. Free phenolic acids 1. PC2 X loading Weights and Y loadings SWEETNESS.8.6.4.2 C Flour.2 Shorts.4 B Flour FRESHNESS 1st Bran CEREAL FLAVOUR AFTERTASTE Vanillic acid Veratric acid FLAVOUR INTENSITY BITTERNESS Syringic acid p OH Benzoic acid GERM LIKE FLAVOUR Ferulic acid.6 Sinapic acid PC1.2.1.1.2.3.4.5 X expl: 81%,14% Y expl: 55%,15% 3rd Bran 1
1..8.6 CASE 2 Flavour and bioactivity of fractionationated rye: Flavour vs. Alk(en)ylresorcinols PC2 X loading Weights and Y loadings 1st Bran CEREAL FLAVOUR AlkrC21: SWEETNESS AFTERTASTE FLAVOUR INTENSITY.4 BITTERNESS.2 B Flour C Flour.2.4 Shorts FRESHNESS AlkrC25: GERM LIKE FLAVOUR AlkrC21: AlkrC19: AlkrC17: Alkr unknown AlkrC19:1 3rd Bran PC1.1.2.3.4.5 X expl: 97%,2% Y expl: 66%,16% CASE 2 Flavour and bioactivity of fractionationated rye: Flavour vs. Lignans 4 PC2 X loading Weights and Y loadings 3 FRESHNESS B Flour C Flour 2 1 1 Shorts CEREAL FLAVOUR GERM LIKE FLAVOUR Syringaresinol Secoisolariresinol Isolariresinol Matairesinol FLAVOUR INT. Lariresinol AFTERTASTE 1st Bran Pinoresinol SWEETNESS 3rd Bran 2 BITTERNESS PC1.2.1.1.2.3.4.5 X expl: 98%,1% Y expl: 47%,2% 11
CASE 3 Tailoring cereal flavour by bioprocessing Different volatile compounds evaporate from same raw material depending on the applied bioprocessing technique Thus, sourdough fermented, germinated and milled rye extrudates deviate from each other both in their sensory attributes and their volatile compounds CASE 3 Tailoring cereal flavour by bioprocessing MilledExtruded Amilo MilledExtruded Akusti X loading Weights and Y loadings.4 PC2.2.2 2 Et furan Hexanal Isobutanal T TOUGH F SWEET Pentanal 2 Me furan Butadione 4 Me 3 penten 2 Butanone 1 Pentanol Butanal 1 Penten 3 ol F ROAST 2 Pentylfuran 3 Furancarboxya 2 Me 2 butenal DMDS 2 Heptanone 3 Pentanon Et.propanoate 2 Me butylaceta 1 Hexanol F CEREAL F FRESH 2 Me butanal T HARD T CRISP Et.acetate Furfural F SOUR 2 Me butanol T POROUS AFTERTASTE F INTENSE 3 Me butanol SourdoughExtruded Amilo SourdoughExtruded Akusti.4 DMS Pretreatment milling (M), germination (G) or sourdough.6 GerminatedExtruded Akusti fermentation (S) dominates GerminatedExtruded Amilo flavour of extruded 3 Me butanal (E) rye.8 PC1.4.2.2.4.6 Heiniö et al. LWT 23b 24 RLH 12
CASE 4 Enzyme aided flavour boosting Enzymatic treatment is a new approach for modifying flavour Intensive, bitter flavour of rye may be caused by small peptides and phenolic compounds, and can be studied by enzyme aided processing Bitterness could be blocked by A Breakdown/ polymerisation of compounds influencing harmfully on flavour B Formation of flavour beneficial flavour precursors, e.g. for Maillard reaction Sensory assessment of enzyme boosted rye Sensory profiles of rye water suspensions with high enzyme dosages (n=2 x 9) O FRESH (F=5.3 p<.1) 1, AFTERTASTE INTENSITY (F=3.37 p<.1) 8, O RYELIKE (F=1.73 ns) 6, 4, F BITTER (F=2.52 p<.5) 2,, O MALT (F=3.65 p<.1) Pectinase Sellulase B glucosidase Protease Amyloglucosidase Reference F CHEMICAL (F=12.41 p<.1) T THICKNESS (F=4.39 p<.1) F SWEET (F=.41 ns) F RYELIKE (F=4.35 p<.1) RLH 26 Most intense bitterness in rye water suspensions caused by protease 13
CASE 4 Enzyme aided flavour boosting Perceived bitterness Bitterness of flour and cracker after Corolase additions (n=2 x 9 1) 5 4 3 2 1 Bitternesss 1 2 Whole rye Whole rye+corolase Endospermic rye Endospermic rye+corolase Endospermic wheat Endospermic wheat+corolase 3 4 5 Flour Cracker CASE 4 Enzyme aided flavour boosting Bitterness, soluble proteins and total phenolics 9, 2, 8, 7, Endospermic wheat+corolase 1,8 1,6 Soluble protein mg/ml 6, 5, 4, 3, Whole rye Whole rye+corolase Endospermic rye+corolase 1,4 1,2 1,,8,6 Total phenolics g/l 2, 1, Endosper mic wheat Endospermic rye,4,2,, 5, 4, 3, 2, 1,, 1, 2, 3, 4, 5, Bitterness ( 5... 5) Soluble protein Total phenolics 14
Conclusions Cereal flavour influenced by volatile and phenolic compounds, amino acids, sugars and fatty acids Tools for relating perceived flavour and flavous active chemical compounds: PLS regression & GC olfactometry Flavour of native grain is mild > Processing required: milling fractionation,sourdough fermentation & baking, germination, heat and enzymatic treatments New tools for developing novel, palatable, healthbeneficial breakfast & snack applications from cereal 29 RLH 15