Preparation and simulation of a taro flavor☆

Guangyong Zhu,Zuobing Xiao*,Rujun Zhou,Donghua Lei

School of Perfume and Aroma Technology,Shanghai Institute of Technology,Shanghai 201418,China

Keywords:Simulation Preparation Formulation Blend Flavor

ABSTRACT Flavors represent a small but signi ficant segment of food industry.Taro gives a pleasant nut-like odor when cooked.Taro flavor can be used in many products,so developing a taro flavor is of interests.This paper concentrates on preparation and simulation of taro flavor according to the notes of taro,which are distinct flavors or odor characteristics.The results show that the notes of taro flavor can be classi fied as caramellic note,roast note,milky note,beany note,green note,aldehydic note,sweet note,nutty note,vegetative note,and fruity note.According to the notes of cooked taro odor and the raw materials selected,a typical taro flavor formula is given.The taro flavor blended is pleasant,harmonious,and has characteristics of the odor of cooked natural taro.

1.Introduction

Taro is a tropical root crop belonging to the monocotyledonous family Araceae.It contains signi ficant amounts of starch, fiber,minerals and mucilages[1].Taro is an endemic food crop of Asia and Paci fic Islands.Taro tastes somewhat like potatoes but less sweet and a little coarser.Its taste is similar to that of buttered popcorn jellybeans,which is a rich flavor.Taro gives a pleasant nut-like odor when cooked(frying,baking,roasting,boiling,or steaming).

A flavor is a substance added to supplement,enhance,or modify the original taste and/or aroma of a food.Flavors represent a small but signi ficant segment of food industry,play an important role and have been widely used in many products such as foods,beverages and cigarettes.It has been demonstrated that sensory characteristics,such as taste and aroma,play an important role in consumer acceptance and preference[2].Consumers will buy a product again if it has good flavor.

The odor oftaro is delightfuland taro flavorcan be used in ice cream,tea,and other food products.However,taro flavorformula has notbeen reported.Therefore,developing a taro flavor is of interests.The technique for formulating a flavor is not unique and there are some general guidelines.A flavor usually contains many ingredients,which are typically organized in a flavor with speci fic role.These ingredients are roughly grouped as primary scents,modi fiers,blenders and fixatives.Note is a distinct flavor or odor characteristic[3-5].This article concentrates on the preparation of taro flavor according to the notes of taro.A taro flavor formulation will be obtained.

2.Experimental

2.1.Materials

All the raw materials for blending taro flavor were food-grade.The synthetic raw materials were purchased from Beijing Aroma Chemical Co.Ltd.The natural raw materials were purchased from Robert Company.

2.2.Methods

The note method for preparing flavor[3-5]was adopted to develop a taro flavor.In the experiment,taro flavorwasconstructed according to the notes of taro odor.Cooked taro was smelled by nose to identify the notes of odor.According to the sensory character in cooked taro,the notes of taro were obtained.Proper chemical ingredients were selected to imitate the odor of taro and make taro flavor.

3.Results and Discussion

3.1.Notes of taro flavor

Creation of a flavor is an art to a large extent,with some scienti fic basis.Identi fication of the notes of taro is one important step.The notes obtained by sensory characters of cooked taro can be classi fied as caramellic note,roast note,milky note,beany note,green note,aldehydic note,sweet note,nutty note,vegetative note,and fruity note.

3.2.Raw materials

According to the notes of taro,corresponding raw materials can be selected to imitate the odor of taro and to blend taro flavor.

Many nitrogen-and sulfur-containing heterocycles have been identi fied in the aroma fractions of foods.In roasted products and heat-treated foods,these heterocycles are formed from reducing sugars and simple or sulfur-containing amino acids by means of Maillard reactions.Thiazoles are examples ofnitrogen-and sulfur-containing heterocycles.Alkythiazoles give green,nutty,roasted,vegetable,or meaty notes.Trimethyl thiazole is reported to have a cocoa,nutty character.2-Isobutytl thiazole is one of the best known thiazoles and has a strong,green odor of tomato leaf.2,4-Dimethyl-5-vinyl thiazole has a nut-like odor.2-Acetyl thiazole is characterized as having a nutty,cereal,and popcorn flavor.4-Methyl-5-thiazoleethanol has a meaty,roast odor[6].These raw materials are selected to present green,nutty,roasted notes in taro flavor.

Pyrazines are also important raw materials to present roast and nutty notes.There has been a long-term interest in pyrazines due to their effects on the flavor of many thermally processed foods.The sensory properties of pyrazines are quite diverse.Alkyl pyrazines generally possess roasted,nut-like notes while methoxypyrazines often possess earthy,vegetable notes.2,3,5-Trimethylpyrazine has a baked potato or roasted nut aroma.2,3-Dimethylpyrazine has a nutty,cocoa-like odor and green note.2-Methoxy-3-methylpyrazine has a raw potato,earthy,bell pepper odor.The acetyl pyrazines typically have a popcorn character,and 2-acetonyl pyrazine has a toasted or burned note[6].Pyrazine compounds are the most important materials for taro flavor.

Pyridine compounds possess a wide range in odor properties.Their contribution to flavor is dependent on their individual structure and concentration in the food.At low concentrations,pyridines typically contribute very pleasant notes,but generally become harsh and offensive at higher concentrations.Green notes are quite common for pyridines.3-Methyl pyridine has a green odor.3-Methyl-4-ethyl pyridine has been characterized as sweet and nutty.2-Acetyl-pyridine is tobacco-like in odor.The three pyridines can be used in taro flavor to provide green,nutty notes.

A number of volatile aliphatic compounds containing nitrogen or sulfur atoms are important aroma constituents.Dialkyl sul fides,alkyl thiols and disul fides belong to this group and occur widely in foods and spices.

Lactones make a signi ficant contribution to flavor of food products,particularly dairy products and alcoholic beverages.They are intermolecular esters of corresponding hydroxyl fatty acids and contribute to the aroma of butter and fruits.Lactones are powerful and distinctive flavorants,responsible for many characteristic notes of fruits,such as peach and apricot.A comparison of odors of δ-and γ-lactones indicates that the increase in the size of the ring in δ-compound increases odor intensity while γ-lactones have some “green”nuances not present in δ-lactones.Many δ-lactones,such as δ-decalactone,δ-dodecalactone,δ-undecalactone,and δ-nonalactone,have a strong creamy,milk-like odor.

Furanones and pyranones are oxygen-containing heterocyclic compounds associated with both caramelized and Maillard flavors.The odor most common in this group of compounds would be caramellike,sweet,fruity,butter-scotch,nutty,or burnt.The caramel character is associated with a planar,contiguous C-alkyl-enol carbonyl group in the molecule.Maltol is one of the first compounds in this class.Ethyl maltol has a caramel odor but is approximately four to six times stronger in flavor strength than maltol.Furaneol,such as maltol and ethyl maltol,is a flavor enhancer for sweet products.Furaneol itself has a burnt pineapple odor.Cyclotene has a very sweet maple character.These materials can be used to impart sweet,caramel-like notes.

Aliphatic aldehydes are among the most important components in perfumery.The lower fatty aldehydes C2-C7 occur widely in nature and impart fruity and roast characters to flavor compositions.These lower aldehydes,such as acetaldehyde,isobutyraldehyde,isovaleraldehyde,and 2-methyl-butyraldehyde,can be used to blend taro flavor and add aldehydic note.

Hydroxyketone acetoin and diketone 2,3-butanedione are commercially important aroma substances.They are usually used for buttery and creamy notes.

Vanilla has a sweet,beany,ethereal odor and characteristic flavor.Vanilla extract is a solution in aqueous ethyl alcohol of the sapid and odorous principles extractable from vanilla beans.Vanilla extracts are used extensively in chocolate and baked products,but more in icecream.Vanillin is the most abundant volatile aromatic constituent of cured vanilla beans.Small quantities are used in perfumery to round and fix sweet,balsamic fragrances.Ethyl vanillin does not occur in nature.Its odor resembles that of vanillin but is approximately three times as strong.Ethyl vanillin gives a sweet,balsamic note to flowery and fruity perfume compositions.Vanilla extract,ethyl vanillin and vanillin can be used to present sweet,milky,and beany notes.

3.3.A typical taro flavor formulation

According to the notes of cooked taro odor and the raw materials selected,taro flavor was obtained.A typical taro flavor formula is shown in Table 1.Five pyrazine compounds in the formula impart roast and nutty notes.2,3,5-Trimethylpyrazine has a baked potato or roasted nut aroma and its taste characteristics are raw,musty,nutty and potato.2,3-Dimethylpyrazine has a nutty,cocoa-like odor and green note.Its taste characteristics are musty,nut skins,cocoa powdery,roasted coffee and bready.2-Methyl-3-methylthiopyrazine has a roasted almond,hazelnut and vegetable aroma.It provides nutty,roasted and earthy with coffee and corn nuances in the formula.2-Methoxy-3-methylpyrazine has a raw potato,earthy,bell pepper odor and its taste characteristics are roasted coffee,nut,cocoa,earthy with a caramellic and baked potato nuance.2-Acetylpyrazine has nutty,popcorn,bread crust odor and its taste characteristics are roasted,nutty,bready,yeasty with popcorn,corn chip nuance.These pyrazine compounds are employed in the taro flavor mainly to present roast and nutty notes[7].2-Acetylpyridine is a colorless liquid with tobacco-like aroma.Its taste characteristics are cornmeal with nutty,bready nuance.It is used with pyrazine compounds to enrich nutty note.Furthermore,it can give the grassy odor like tobacco.

3-(Methylthio)propanol has a powerful,sweet,soup or meat-like odor and flavor in high dilution.Its taste characteristics are metallic,tomato,potato,anchovy-like with savory brothy and malt-like nuances.3-(Methylthio)propionaldehyde has a powerful,onion,meat-like odor and a flavor reminiscent of potato chip.It has a pleasant,warm,meat and soup-like flavor at low levels.These two materials are adopted in the formula mainly to present vegetative note[7].Methyl sul fide has an intense,unpleasant odor,wild radish,cabbage-like.It can be tolerated as a green vegetable note only at very low levels(0.1×10-6to 3.0 × 10-6g·g-1).Aroma characteristics are sulfureous,dimethyl sulfide,creamy,tomato, fishy,scallop,berry fruity and vegetative nuances.Methyl sul fide is also used in the taro flavor mainly to impartvegetative note.

2,3-Butadione has a very strong buttery odor in very dilute solution,and has sweet,buttery,creamy and milky taste characteristics.It is a constituentof many fruitand food aromas and well-known as a constituent of butter.It is used mainly in aromas for buttery and milky notes.Butyl butyryl lactate has an odor similar to milk,mild cheese,butter and cream.Its taste characteristics are creamy mouthfeel,buttery dairy,waxy,milky with coconut and cheesy nuances.It is employed in the formula mainly to give buttery,milky and cheesy nuance.

Lactones are used in the formula for imparting milk-like,nutty and fruity odors.δ-Lactones can make the flavor odor soft and gentle.γ-Decalactone hasa pleasant,fruity,peach-like odor.Its taste characteristics are creamy,fatty,oily,buttery sweet,coconut,fruity and peach-like.δ-Decalactone has an oily,peach odor and taste,presenting waxy,coconut,lactonic,fatty,creamy,nutty and fruity characteristics.δ-Undecalactone has a creamy,peach-like aroma,and creamy,coconut,milky,creamy,lactonic and butter fat with a waxy,fruity nuance.γ-Nonalactone,socalled “aldehyde C18”,has a strong odor reminiscent of coconut and a fatty,peculiar taste,occurring in many foods and being a pale yellow liquid.It has wide applications,similar to those of gama-octalactone,in aroma compositions and perfumery.δ-Lactones,butadione,and butyl butyryl lactate construct the buttery,milky,nutty,fruity notes of taro flavor.

Table 1 A typical taro flavor formula

4-Methyl-5-thiazoleethanol has a disagreeable odor typical of thiazole compounds,somewhat pleasant,reminiscent of beef and nut-like on dilution.Sulfurol acetate has an odor reminiscent of meat.Its taste characteristics are meaty,brothy,bready and brown with a beefy,bloody and chicken note.The two materials can enrich taro flavor with meaty note and vegetative note.

Acetaldehyde is a colorless, flammable liquid with a characteristic pungent,penetrating,ethereal odor.As a flavor ingredient/enhancer,acetaldehyde helps create naturalness,fruitiness and juiciness.It imparts green and roast characters to a flavor.Its fresh character is appropriate in taro flavor.It can also add aldehydic note.

Maltol has a caramel-butterscotch odor and in solution it has a jamlike odor.It is also reported to have a suggestive of fruity,strawberry aroma in dilute solution.Its taste characteristics are sweet,caramellic,cotton candy,with jamy fruity and berry notes.It is used in aroma compositions with a caramel note and as a taste intensi fier in flavors.Ethyl maltol has a very sweet,fruit-like odor of immense tenacity and sweet,fruity taste with initial bitter-tart flavor.It is four to six times more potent than maltol.It is used in aroma compositions and as a flavor enhancer in food,beverages and tobacco.The two materials are employed in taro flavor to give caramel note.

Vanilla can act as a blender,a material that brings various flavor characteristics together.Vanilla tincture is used in taro flavor to present sweet,milky,and beany notes.It is a natural material and can enhance the natural feeling of taro flavor[6,8].

The flavor blended according to Table 1 has a pleasant,harmonious odor of natural cooked taro.

This paperconcentrates on the preparation ofa taro flavor according to the notes of cooked taro.Based on the odor of cooked taro,the notes oftaro flavorobtained are classi fied as caramellic note,roastnote,milky note,beany note,green note,aldehydic note,sweet note,nutty note,vegetative note,and fruity note.According to the notes of taro,corresponding raw materials are selected to develop a taro flavor.A typical taro flavor formula is given.The taro flavor blended according to the formula is pleasant,harmonious,and has characteristic odor of cooked natural taro.