Smells like choco­late ...

Re­searchers ob­tain choco­late aroma from jack­fruit seeds.

The Star Malaysia - Star2 - - Science - By EL­TON ALISSON

THE seeds of the hard jack­fruit (Ar­to­car­pus het­ero­phyl­lus Lam.) can be sub­sti­tuted for co­coa in the for­mu­la­tion of prod­ucts with choco­late aroma but with­out choco­late fla­vor.

A group of re­searchers at the Univer­sity of São Paulo’s Luiz de Queiroz Col­lege of Agri­cul­ture (ESALQ-USP), in col­lab­o­ra­tion with re­searchers at the Tech­nol­ogy Col­lege (FATEC) in Piraci­caba and Piraci­caba Methodist Univer­sity (UNIMEP) in Brazil and the Univer­sity of Read­ing in the UK, have dis­cov­ered that volatile com­pounds found in jack­fruit seeds pro­duce many of the aro­mas ob­tained from co­coa beans.

As a re­sult, these seeds, which are cheaper and more abun­dant, are po­ten­tial sub­sti­tutes for co­coa in prod­ucts with choco­late aroma, such as cos­met­ics, foods and bev­er­ages.

The study was de­scribed in an ar­ti­cle pub­lished in the Amer­i­can Chem­i­cal So­ci­ety’s Jour­nal of Agri­cul­tural and Food Chem­istry.

“We found that jack­fruit seeds con­tain large amounts of pyrazines, the main com­pounds that de­ter­mine choco­late aro­mas,” said Solange Guidolin Can­ni­atti Brazaca, a pro­fes­sor at ESALQ-USP and prin­ci­pal in­ves­ti­ga­tor for the project.

The dis­cov­ery was ac­ci­den­tal, Brazaca said: it hap­pened dur­ing a nu­tri­tion stu­dent’s sci­en­tific ini­ti­a­tion project at UNIMEP.

The aim of the project was to use jack­fruit seed flour to make cakes, bis­cuits and bread be­cause jack­fruit seeds con­tain high pro­por­tions of starch and pro­teins.

When they roasted the seeds as a first step to make flour, the re­searchers no­ticed that the seeds re­leased an aroma very sim­i­lar to that of choco­late.

The dis­cov­ery in­spired them to start a re­search project with the goal of iden­ti­fy­ing the volatile com­pounds in jack­fruit pulp and seeds in 2011.

They stud­ied both the hard and the soft va­ri­eties of jack­fruit. The hard va­ri­ety has larger fruit and firmer, crisper flesh. The re­sults showed that hard jack­fruit seeds had a more in­tense choco­late aroma.

To find the best method of ob­tain­ing flour with an aroma sim­i­lar to that of choco­late from roasted seeds of the hard jack­fruit, food sci­en­tist Fer­nanda Papa Spada un­der­took a PhD project with a schol­ar­ship from FAPESP, su­per­vi­sion by Brazaca, and col­lab­o­ra­tion with re­searchers at the Univer­sity of Read­ing.

Dur­ing the project, the re­searchers pro­duced flour from jack­fruit seeds that had been roasted and acid­i­fied or fer­mented be­fore dry­ing.

The dif­fer­ent batches of flour were roasted for dif­fer­ent lengths of time and at dif­fer­ent tem­per­a­tures, us­ing sim­i­lar roast­ing and fer­ment­ing pro­ce­dures to those used to ob­tain com­pounds with choco­late aroma from co­coa beans.

Anal­y­sis showed that fer­men­ta­tion was the best method to ob­tain flour with an aroma sim­i­lar to choco­late from jack­fruit seeds.

How­ever, the re­searchers ob­served that when seeds were only dried and roasted, with­out be­ing fer­mented or acid­i­fied, they also con­tained a large num­ber of com­pounds, and their high amino acid and sugar con­tents re­acted dur­ing roast­ing to pro­duce odours char­ac­ter­is­tic of choco­late.

“We tried acid­i­fy­ing roasted jack­fruit seeds to re­lease more pyrazine, but some un­de­sir­able resid­ual odours re­sulted from acid­i­fi­ca­tion,” Brazaca said. “So we left aside acid­i­fi­ca­tion and opted in­stead for nat­u­ral fer­men­ta­tion fol­lowed by dry­ing.”

Us­ing gas chro­matog­ra­phy cou­pled with mass spec­trom­e­try (a tech­nique em­ployed to sep­a­rate and an­a­lyse mix­tures of volatile sub­stances), the re­searchers also iden­ti­fied sev­eral com­pounds as­so­ci­ated with choco­late aroma in the jack­fruit seed flour, in­clud­ing 3-methylbu­tanal, 2,3-di­ethyl-5-methyl-pyrazine and 2-phenylethyl ac­etate.

They then used ol­fac­tom­e­try to an­a­lyse each of these volatile com­pounds and asked a panel of trained ex­perts to de­scribe the in­ten­sity and other char­ac­ter­is­tics of the com­pounds’ aro­mas.

The panel’s de­scrip­tions as­so­ci­ated fer­mented jack­fruit flour with more caramel, hazel­nut and fruity aro­mas than for acid­i­fied flour.

“Co­coa beans were found to con­tain more pyrazine com­pounds than co­coa, and fer­mented seeds had a more in­tense choco­late aroma ow­ing to the for­ma­tion of alde­hy­des and es­ters, which are char­ac­ter­is­tic of co­coa,” Spada said.

The re­searchers then added jack­fruit seed flour to a cap­puc­cino mix­ture to find out whether it could be used as a sub­sti­tute for choco­late aroma ex­tracted from co­coa.

The re­sults of the test showed that jack­fruit seed flour could be used as a sub­sti­tute for choco­late aroma from co­coa with­out in­ter­fer­ing with the drink’s cof­fee flavour.

“The tasters found no difference be­tween the choco­late aroma ob­tained from jack­fruit seeds and the choco­late aroma pro­duced by co­coa beans,” Brazaca said.

The re­searchers now plan to eval­u­ate the use of two micro­organ­isms cur­rently used to fer­ment co­coa – Kluyveromyces marx­i­anus and Sac­cha­romyces cere­visiae – in fer­ment­ing seeds of the hard jack­fruit and to es­ti­mate the micro­organ­isms’ ef­fect on the pro­duc­tion of the choco­late aroma.

“Our ini­tial idea was to pro­mote more com­plete use of the jack­fruit,” Brazaca said. “In Brazil, only the pulp is used, cor­re­spond­ing to 30% of its weight, and the re­main­ing 70%, con­sist­ing of the rind, cen­tral por­tion and seeds, is dis­carded.”

Boiled jack­fruit seeds are con­sumed in Asia, whereas in Brazil, which pro­duces more jack­fruit than any other coun­try in the Amer­i­cas, jack­fruit seeds are con­sid­ered waste, Brazaca noted. – Agên­cia FAPESP

— Vis­ual Hunt

A study shows com­pounds found in jack­fruit seeds pro­duce many of the aro­mas ex­tracted from co­coa beans and can be used in the man­u­fac­tur­ing of food prod­ucts and cos­met­ics.

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