A techno-economic perspective on a microwave extraction process for efficient protein recovery from agri-food wastes

Indus ial C ops & P oduc s 186 (2022) 115166 A ailable online 8 June 2022 0926-6690/© 2022 The Au ho (s). Published by Else ie B.V. This is an open access a icle unde he CC BY-NC-ND license (h p://c ea i ecommons.o g/licenses/by- nc-nd/4.0/). A echno-economic pe spec i e on a mic owa e ex ac ion p ocess o e icien p o ein eco e y om ag i- ood was es C is ina Ba ios a , b , Ma ina Fe n´ andez-Delgado a , b , Juan C. L´ opez-Lina es a , b , Ma ía Te esa Ga cía-Cube o a , b , M´ onica Coca a , b , Susana Lucas a , b , * a Ins i u e o Sus ainable P ocesses, D . Me gelina s/n, 47011 Valladolid, Spain b Depa men o Chemical Enginee ing and En i onmen al Technology, School o Indus ial Enginee ing, Uni e si y o Valladolid, D . Me gelina, s/n, 47011 Valladolid, Spain ARTICLE INFO Keywo ds: Ag i- ood was e P o ein eco e y Mic owa e-assis ed ex ac ion Economic analysis ABSTRACT Di e en ag i- ood was es (b ewe ´s spen g ain (BSG), spen co ee g ound (SCG) and kale s ems) ha e been p oposed as excellen sou ces o p o ein-en iched ex ac s wi h an an ioxidan capaci y. The op imiza ion o he mic owa e-assis ed hyd o he mal and alkali ex ac ion has been compa ed in his s udy. F om a echnical and economic poin o iew, he ex ac ion o BSG unde op imal condi ions (110 ºC, 10 min and 0.5 M NaOH) p o ided he bes ex ac wi h a con en o 14.6 kg p o ein/100 kg BSG (d y ma e ), 13.8 g/L o o al suga s and an an ioxidan ac i i y (DPPH me hod) o 17.1 mg olox equi alen s (TE)/g BSG. This ex ac had he lowes p oduc ion cos (29.9 € /kg) and a minimum selling p ice o 51.7 € /kg, es ima ed o an ex ac ion pilo plan o 15 kg/h o BSG. The mic owa e-assis ed hyd o he mal ex ac ion o kale s ems, a no el was e in he bio e ine y con ex , also p o ides bioac i e and g een ex ac s o comme cial in e es . The e is a need o speci ic esea ch s udies ela ed o bio e ining o ag i- ood was es o p oduce p o eins o ood, con ibu ing o he de elopmen o a u u e sus ainable and clima e-neu al ag icul u e. The p oposed echno-economic assessmen ep esen s an impo an ad ance in esea ch and scaling-up o mic owa e-assis ed ex ac ion p ocesses o p o ein eco e y om ag i- ood was es. 1. In oduc ion Eno mous amoun s o ag i- ood was e (AFW) a e gene a ed in a ious s ages o he en i e ag i- ood supply chain (including p ocessing) (Bha , 2021). AFW is an excellen sou ce o bioac i e compounds o exploi , including p o eins, suga s, lipids, and phenolics (Popo ic e al., 2022). Acco ding o Ma i´ c e al. (2018), Eu ope gene a es abou 100 million onnes o was e each yea in he ood p ocessing indus y. The concep o conside ing by-p oduc s as a aw ma e ial o he eco e y and p oduc ion o se e al co-p oduc s using g een me hods wi hin he in eg a ed bio e ine y model has g ea in e es and po en ial (Fie ascu e al., 2020) conce ning he ci cula economy policies. In his con ex , b ewe s’ spen g ain (BSG) is he mos abundan by-p oduc in he bee b ewing p ocess and is a ailable h oughou he yea (Pa chami e al., 2021). This ma e ial consis s o he ba ley g ain husks ob ained as solid esidue a e he p oduc ion o wo . I comp ises app oxima ely 85% o he o al was e gene a ed in his indus y (Li e al., 2021); p oducing 0.2 kg we BSG pe li e o bee (Pa chami e al., 2021). In 2019, 38.2 million me ic ons o we BSG we e p oduced wo ldwide (Pa chami e al., 2021). This esidue con ains a ela i ely la ge amoun o p o ein (18–31% w/w) and ibe , suga s, and mine als. This was e is no mally only used as animal eed o is di ec ly disca ded (Li e al., 2021). Ano he in e es ing AFW is spen co ee g ounds (SCG). Co ee is one o he mos consumed comme cial oods and he second mos expo ed p oduc by eme ging coun ies (Ribei o e al., 2021). The co ee indus y p oduces a la ge amoun o was e which, acco ding o Valdes e al. (2020), may ep esen somewhe e o e 50% o he mass o all he co ee beans in he p oducing coun ies. The wo ld p oduc ion o co ee in 2018 was a ound 9.5 million ons (de O ´ alo a e al., 2020) and app oxima ely 0.91 g o SCG is p oduced o 1 g o co ee g ound (Tun e al., 2020). SCG con ains signi ican p o ein con en (up o 12% w/w) (Mussa o e al., 2011; Ribei o e al., 2021). On he o he hand, kale, a ege able om he B assica genus, has been a ac ing a en ion o he las ew decades due o i s high an ioxidan and die a y ibe con en (Casajús e al., 2021). B assica genus c ops a e one o he en mos economically essen ial ege ables in global ag icul u e and ma ke s. In * Co espondence o: Depa men o Chemical Enginee ing and En i onmen al Technology, Uni e si y o Valladolid, D . Me gelina s/n, 47011 Valladolid, Spain. E-mail add ess: [email p o ec ed] (S. Lucas). Con en s lis s a ailable a ScienceDi ec Indus ial C ops & P oduc s jou nal homepage: www.else ie .com/loca e/indc op h ps://doi.o g/10.1016/j.indc op.2022.115166 Recei ed 9 Feb ua y 2022; Recei ed in e ised o m 5 May 2022; Accep ed 28 May 2022 Indus ial C ops & P oduc s 186 (2022) 115166 2 2012, he global p oduc ion o B assica c ops was almos 92 million me ic onnes, g own in 150 di e en coun ies and occupying 5.4 million hec a es. Spain, Mexico, I aly, F ance, and he USA p oduce o e 0.2 million me ic onnes pe yea . A ound 7% o his ege able is dis- ca ded as was e (F ancisco e al., 2017). Acco ding o Megías-P´ e ez e al. (2020), he a e age composi ion o kale is wa e (89%), ibe (4%), p o eins (3%), lipids (1.5%), and low molecula weigh ca bohyd a es (1%). So esh kale has mode a e le els o p o ein (1.6–5.9 g/100 g). In ecen yea s, he ood indus y has ocused on s udying he an- si ion om he use o animal p o eins o plan -based p o eins (Yang and Sagis, 2021). This de elopmen is due o he en i onmen al aspec s o mea p oduc ion and he need o new p o ein sou ces o he highe global popula ion (Pa chami e al., 2021). Ex ac ed p o eins ha e p ope ies ha a e bo h bio unc ional (nu i ional p ope ies o appli- ca ion in eed/ ood and pha maceu ical sec o s) and echno- unc ional (s uc u es echnical applica ions such as packaging wi h solubili y o ne wo k o ma ion and iscosi y) (Yada e al., 2020). So i is necessa y o ind an al e na i e, less esou ce-in ensi e sou ce o p o ein o ood, as well as o o he applica ions. The con en ional p o ein ex ac ion me hod has some d awbacks, such as he ac ha i equi es a la ge amoun o wa e and ene gy, he p o ein ex ac ion yield dec eases when high pu i y p o ein ex ac s a e ob ained, o he p ocess may al e he p o ein s uc u e (Yang and Sagis, 2021). The p oblem o ex ac ing p o ein in his ype o was e wi h high yields is ha se e al componen s, such as cellulose and lignin, o m a complex ne wo k and ap he p o ein inside (Li e al., 2021). The e o e, chemical ea men s ha e been applied. Con en ional alkali ex ac ion has been p o ed o be an app op ia e p o ein ex ac ion me hod, bu i also has he disad an age o a long ex ac ion ime (Li e al., 2021). Fo his eason, physical me hods a e gene ally used oge he wi h he chemical me hod o o e come he abo emen ioned disad an ages. Mic owa e-assis ed ex ac ion (MAE) could be a cos -e ec i e, e icien and s aigh o wa d me hod o assis in p o ein ex ac ion. Mic owa e echnology has been conside ed a g een and eco- iendly me hod o dis up he cell wall wi h ela i ely low ene gy inpu , a apid ea men ime and he a oidance o he u iliza ion o haza dous subs ances. Mi- c owa es in e ac selec i ely wi h pola molecules and induce in a- cellula hea ing. This hea and p essu e loca ed in he cell walls lead o cell dis up ion allowing and imp o ing he ex ac ion o in acellula p o eins. MAE was hus applied o enhance he e icacy o p o ein ex ac ion and he co-ex ac ion o phenolic compounds om se e al AFW, such as BSG, SCG, and kale s ems. The p esen wo k a emp s o s udy he use o se e al was es om he ood and be e age indus y (BSG, SCG, and kale s ems) o achie e bioac i e p o ein-en iched ex ac s wi h an ioxidan ac i i y. In his con ex , he MAE p ocess was p oposed, in which he in luence o h ee pa ame e s ( empe a u e, ime, and NaOH concen a ion), as well as he compa ison o alkali and hyd o he mal ex ac ion, a e e alua ed using he esponse su ace me hodology. The e alua ed maximizing esponse was he p o ein eco e y. On he o he hand, he o al phenolic con en (TPC), o al la onoid con en (TFC), and an ioxidan ac i i y (DPPH me hod) we e measu ed a he op imum alue o each scena io e alu- a ed. In addi ion, a p elimina y economic s udy was ca ied ou o compa e he op imal scena ios o p o ein ex ac ion om AFW. Fo his pu pose, he o al cos s o he ex ac ion and a e sa ile plan wi h a capaci y o 15 kg/h o ag o-was e o p o ein eco e y om AFW, along wi h he ma ke alue o he p o ein ha could be heo e ically p o- duced, we e es ima ed. This esea ch s udy ep esen s a signi ican ad ance in he de el- opmen o new s a egies o he p oduc ion, ex ac ion, p ocessing and ma ke ing o new al e na i e p o eins om new sou ces ha could be conside ed o animal eed and di ec human consump ion. I is wo h men ioning ha his s udy is he i s o compa e, om a echnical and economic poin o iew, he mic owa e-assis ed hyd o he mal and al- kali ex ac ion o p o ein om a ious AFW. Mo eo e , a ew e e ences we e ound ela ed o p o ein ex ac ion om BSG and SCG, bu none abou kale was e o i s alo iza ion. 2. Ma e ials and me hods 2.1. Raw ma e ials In his case, AFW was used, namely BSG, SCG, and kale s ems. The SCG was p o ided by PROSOL P oduc os Solubles (Ven a de Ba˜ nos, Spain), he BSG was dona ed by he B ewe y Mahou San Miguel (Bu gos, Spain), and he kale s ems we e supplied by Na u Snacks (Ped ajas de San Es eban, Spain). The h ee aw ma e ials we e d ied a 60 ◦C in an o en and milled using a co ee g inde (Tau us A oma ic, 150 W). In his way, a pa icle size lowe han 1 mm and mois u e con en lowe han 3% o he h ee cases was achie ed. 2.2. Mic owa e-assis ed alkali ex ac ion A mul iwa e PRO SOLV eac o 50 Hz wi h Ro o ype 16HF100 (An on Paa GmbH, Aus ia, Eu ope) was used o ex ac he p o ein om he AFW, wi h a solid o liquid a io o 10% (w/ ). I is ope a ed wi h con inuous empe a u e con ol o he applied mic owa e ene gy ( o mo e de ails, see L´ opez-Lina es e al., 2019). The aw ma e ials and sol en we e mixed (5 g d y weigh aw ma e ial and 50 mL o sol en ) in each o he p essu e essels o he mul iwa e eac o . The eac o wa med up and he ex ac ion ime was ini ia ed when each un a ained he equi ed empe a u e. When he expe imen al uns we e inished, he mic owa e equipmen cooled he p essu e essels o he eac o down o a empe a u e o 50 ◦C. The slu y was acuum il e ed (when he sol en was wa e ), o cen i uged a 10,000 pm o 10 min (in he case o alkali sol en ), o sepa a e he solid and liquid phases. In addi ion, he solid phase was washed wi h dis illed wa e and d ied a 50 ºC o 48 h. The solid was hen weighed o de e mine he solid eco e y (SR) (g solid ac ion/100 g d y aw ma- e ial). The TPC, TFC, DPPH, and o al suga con en we e de e mined in he liquid phase. Finally, he p o ein in he solid phase was analyzed. 2.3. Expe imen al design In o de o selec he op imal condi ions o p o ein ex ac ion using mic owa e-assis ed (alkali o hyd o he mal) ea men om he h ee chosen aw ma e ials, a cen al composi e expe imen al design was used. The ac o s we e empe a u e, ime, and sodium hyd oxide con- cen a ion. Acco ding o li e a u e (Qin e al., 2018; Con e as e al., 2019; Du e al., 2020; Samsalee and So ho n i , 2021; Ribei o e al., 2021), highe p o ein ex ac ion yields we e achie ed ope a ing in a basic medium, being NaOH he mos widely employed sol en . Sol en concen a ions used a e usually less han 1 M and ex ac ion empe a- u es below 120ºC in o de o a oid possible p o ein dena u a ion, deg ada ion o p ecipi a ion p ocesses. Sho ex ac ion imes a e equi ed using mic owa e echnology (<15 min). Table 1 shows he coded and uncoded alues o ac o s in he expe imen al designs whose da a we e p ocessed and analyzed wi h he so wa e S a g aphics Cen u ion XVIII. 2.4. Analy ical me hods 2.4.1. Raw ma e ial composi ion The composi ion o he p oposed aw ma e ials, i.e., ex ac i es, s uc u al ca bohyd a es (cellulose and hemicellulose), lignin, and ash con en we e measu ed using he analy ical me hodology o he Na ional Renewable Ene gy Labo a o y (NREL) (Slui e e al., 2005, 2008, 2011). The expe imen s we e ca ied ou in iplica e and he a e ages o he esul s a e shown. The o al p o ein con en o he aw ma e ial and ex ac ed solids was analyzed by he Kjeldahl acid diges ion me hod o P abhuzan ye e al. (2019). The SR om he ex ac ions was de e mined acco ding o C. Ba ios e al. Indus ial C ops & P oduc s 186 (2022) 115166 3 L´ opez-Lina es e al. (2021). 2.4.2. Chemical cha ac e iza ion o he liquid ex ac s The o al suga concen a ion was de e mined by he Phenol-Sul u ic Acid Me hod, a colo ime ic me hod ha uses D-glucose as s anda d (Nielsen, 2017). The esul s a e exp essed as g o o al suga L −1 o he liquid ex ac . The Folin-Ciocal eu me hod (Single on and Rossi, 1965) was used o analyze he TPC. This me hod uses gallic acid as s anda d, and he e- sul s a e exp essed as mg gallic acid equi alen s (GAE) g −1 o he d y aw ma e ial. On he o he hand, o analyze he TFC, he colo ime ic me hod desc ibed by Zhishen e al., (1999) was employed, using ca echin as s anda d. The TFC is exp essed as mg o ca echin equi alen s (CE) g −1 o he d y aw ma e ial. In o de o measu e he an ioxidan capaci y o he liquid ex ac s ob ained om he ea men wi h mic owa es, he DPPH adical sca - enging me hod desc ibed by B and-Williams e al. (1995) was used. The s anda d used was T olox (6-hyd oxy-2, 5,7,8- e ame hylch ome-2-ca - boxylic acid), and he esul s a e shown as mg o T olox equi alen s (TE) g-1 o he d y aw ma e ial. The analy ical de e mina ions we e ca ied ou in iplica e, and he a e age esul s we e indica ed. Rela i e s anda d de ia ions we e below 2%. 2.4.3. Calcula ion o p o ein ex ac ion yield The p o ein ex ac ion yield was calcula ed as he a io o he ex ac ed p o ein o he ini ial p o ein in he aw ma e ial (RM), using Eq. (1). P o ein ex ac ion yield (%) = Ini ial p o ein in RM −solid p o ein Ini ial p o ein in RM ⋅100 (1) 2.5. De ini ion o scena ios The p o ein ex ac ion p ocess om AFW has wo s ages: he i s is a solid-liquid MAE, ob aining a slu y s eam. The nex s age sepa a es he liquid and solid phases o ob ain wo s eams; he liquid s eam being ich in p o eins and phenols, while solid s eam is was e. Fou scena ios ha e been conside ed o e alua e he bes ope a ing condi ions o p o ein ex ac ion. In addi ion, an economic e alua ion was ca ied ou . Scena io 1 (BSG-NaOH), Scena io 2 (SCG-NaOH), and Scena io 3 (kale-NaOH) consis in a MAE using an alkali solu ion as he sol en . Scena io 4 (kale-H 2 O) comp ises a MAE using wa e as he sol en . A e ex ac ion, all ou scena ios conside a liquid and solid phase sepa a ion s age. The ope a ing condi ions o he MAE we e selec ed based on p e i- ously published esul s and p e ious expe imen al esul s (da a no shown). Two esponse a iables ha e been compa ed: he p o ein Table 1 Expe imen al design o he ou scena ios p oposed. Run Tempe a u e (◦C) Time (min) NaOH concen a ion (M) Run Tempe a u e (◦C) Time (min) NaOH concen a ion (M) Coded Real Coded Real Coded Real Coded Real Coded Real Coded Real (A) (B) Scena io 1 (BSG-NaOH) 1 0 90 0 6.25 0 0.3 Scena io 2 (SCG-NaOH) 1 0 90 0 10 1.682 1.31 2 1 110 -1 2.50 1 0.5 2 -1 70 1 15 1 1 3 0 90 0 6.25 1.682 0.64 3 0 90 1.682 18.41 0 0.55 4 -1.682 56 0 6.25 0 0.3 4 1 110 1 15 -1 0.1 5 -1 70 1 10.00 -1 0.1 5 1.682 124 0 10 0 0.55 6 0 90 0 6.25 0 0.3 6 0 90 0 10 -1.682 0 7 -1 70 -1 2.50 1 0.5 7 1 110 1 15 1 1 8 1 110 -1 2.50 -1 0.1 8 -1 70 1 15 -1 0.1 9 0 90 0 6.25 0 0.3 9 0 90 0 10 0 0.55 10 0 90 -1.682 0.00 0 0.3 10 -1 70 -1 5 -1 0.1 11 1 110 1 10.00 1 0.5 11 1 110 -1 5 -1 0.1 12 0 90 0 6.25 0 0.3 12 -1 70 -1 5 1 1 13 -1 70 -1 2.50 -1 0.1 13 1 110 -1 5 1 1 14 0 90 1.682 12.56 0 0.3 14 -1.682 56 0 10 0 0.55 15 -1 70 1 10.00 1 0.5 15 0 90 0 10 0 0.55 16 0 90 0 6.25 0 0.3 16 0 90 -1.682 1.59 0 0.55 17 1 110 1 10.00 -1 0.1 18 0 90 0 6.25 0 0.3 19 0 90 0 6.25 -1.682 0 20 1.682 124 0 6.25 0 0.3 Run Tempe a u e (◦C) Time (min) NaOH concen a ion (M) Run Tempe a u e (◦C) Time (min) NaOH concen a ion (M) Coded Real Coded Real Coded Real Coded Real Coded Real Coded Real (C) (D) 1 -1.414 62 0 10 – 0 Scena io 3 (kale-NaOH) 1 0 90 0 10 0 1 Scena io 4 (kale-wa e ) 2 0 90 0 10 – 0 2 0 90 0 10 0 1 3 0 90 0 10 – 0 3 1.682 124 0 10 0 1 4 -1 70 1 15 – 0 4 -1.682 56 0 10 0 1 5 1 110 1 15 – 0 5 1 110 -1 5 -1 0.5 6 -1 70 -1 5 – 0 6 -1 70 -1 5 1 1.5 7 0 90 -1.414 2.93 – 0 7 0 90 0 10 1.682 1.84 8 1.414 118 0 10 – 0 8 0 90 1.682 18.41 0 1 9 1 110 -1 5 – 0 9 1 110 1 15 1 1.5 10 0 90 1.414 17.07 – 0 10 -1 70 -1 5 -1 0.5 11 0 90 -1.682 1.59 0 1 12 -1 70 1 15 -1 0.5 13 1 110 1 15 -1 0.5 14 -1 70 1 15 1 1.5 15 1 110 -1 5 1 1.5 16 0 90 0 10 -1.682 0.16 C. Ba ios e al. Indus ial C ops & P oduc s 186 (2022) 115166 4 eco e y in o he was es (ag o-indus ial and ui / ege able was es) and he sol en used (alkali ex ac ion o wa e ). The p ocess low conside ed is p esen ed in Fig. 1. 2.6. Economic e alua ion A p elimina y and compa a i e economic s udy o an indus ial plan o p o ein ex ac ion-pu i ica ion om di e en AFW was ca ied ou . A plan wi h a p oduc ion capaci y o 15 kg/h o aw ma e ial (BSG, SCG, and kale s ems) and a humidi y o 20% w/w was selec ed as he basis o he economic analysis. This low a e was chosen based on he lowes p oduc ion o he h ee aw ma e ials in Cas ile & Le´ on (Spain) o ensu e con inuous yea - ound p oduc ion. In his case, only 280 o kale we e p oduced in his egion in 2020 (MAPA, 2021). In o de o es ima e he minimum selling p ice o p o ein, wo s ages ha e been conside ed. Fi s , he ups eam (ex ac ion +cen i uga ion) has been igo ously designed based on he labo a o y da a using he op imal condi ions o each scena io; he ela ed equipmen cos s we e also calcula ed. Second, he cos o he pu i ica ion sec ion (p ecipi a ion and sp ay-d ying) was es ima ed. The downs eam p ocesses a e he mos expensi e pa o he p o ein ex ac ion-pu i ica ion p ocess, and hei associa ed cos can be a ound 70% o he o al plan cos s (K uschi z and Nide zky, 2020; Łojewska e al., 2016). The heo e ical p o ein p oduc ion was calcu- la ed on his basis, conside ing ha he o al p ecipi a ed p o ein was 70% o he heo e ical. The ma ke alue o he bioac i e p o ein ex ac was es ima ed in o de o e i y whe he he p ocess could become economically iable and i he selling p ice could be compe i i e. The Lang ac o s me hod, ex ensi ely used in indus ial enginee ing o calcula e he di e en plan cos s, was applied o his p elimina y economic s udy. A comple e me hod is desc ibed in he li e a u e (Sinno , 2005). Fi s , he ups eam equipmen was designed and he associa ed equipmen cos (PCE) was es ima ed using he CAPCOST so wa e. To calcula e he o al plan PCE, he ups eam PCE was di ided by 0.3 in o de o be able o apply he Lang Fac o me hod o calcula e he To al In es men Cos (TIC) o he whole p ocess. A e ha , he TIC was calcula ed using he solid-liquid c i e ia o he Lang ac o me hod. Eqs. (2)–(4) we e used o es ima e he plan cos s. Physical Plan Cos (PPC) =PCE * 3⋅15 (2) Fixed Capi al Cos (FCC) =PPC * 1⋅40 (3) TIC =FCC * 1⋅05 (4) The cos s o he p oposed aw ma e ials we e es ima ed om he li e a u e: p ocess wa e : 3.16 € /m 3 (Aqua all, 2017), and NaOH: 4 € /kg (Sinno , 2005). The a e age cos conside ed o he AFW was 20 € / because he ange o he BSG cos was 20 – 35 € / (Fe n´ andez-Delgado e al., 2019), while he SCG cos was a ound 20–60 $/ (A abani e al., 2019, Kamil e al., 2019), hough no da a we e ound o kale. The ollowing assump ions we e necessa y o es ima e he plan p o i s and he minimum selling p ice o he p o ein ex ac . All sce- na ios and equipmen amo iza ion had a plan li e ime o 10 yea s. The annual p oduc ion cos s pe kg o p o ein we e es ima ed conside ing ha he plan wo ks 8000 h/y. Finally, he minimum sale p ice could be calcula ed, conside ing a ne p esen alue (NPV) o he plan o 0 € and an in e nal a e o e u n (IRR) o 10% (Fe n´ andez-Delgado e al., 2022). Fig. 1. Flow diag am o he p oposed scena ios. Flow diag ams elabo a ed acco ding o UNE ISO 10628:2015. C. Ba ios e al. Indus ial C ops & P oduc s 186 (2022) 115166 5 3. Resul s and discussion 3.1. Cha ac e iza ion o ag i- ood was es Fi s ly, he composi ion achie ed o SCG was he ollowing (% w/w d y ma e ): cellulose, 16.3 ±0.1; hemicellulose, 27.7 ±0.7, acid- insoluble lignin (AIL), 38.5 ±0.7; acid-soluble lignin (ASL), 0.7 ±0.1; ex ac i es, 12.4 ±0.4 (glucose in ex ac i es, 0.0 ±0.0); ash, 0.1 ±0.0; ace yl g oups, 0.4 ±0.0 and p o ein, 12.1 ±0.4 (Lopez-Lina es e al., 2021). On he o he hand, he composi ion was (% w/w d y ma e ) o BSG: cellulose, 32.6 ±0.6; hemicellulose, 23.2 ±0.1, AIL, 13.0 ±0.5 ASL, 1.3 ±0.0; ex ac i es, 14.2 ±0.3 (glucose in ex ac- i es, 0.8 ±0.0); ash, 13.0 ±0.1; ace yl g oups, 0.8 ±0.0; and p o ein, 22.04 ±0.2. Finally, he composi ion o kale s ems was (% w/w d y ma e ): cellulose, 15.0 ±0.0; hemicellulose, 13.0 ±0.1, AIL, 2.1 ±0.3; ASL, 1.8 ±0.0; ex ac i es, 46.9 ±0.7 (glucose in ex ac i es, 7.5 ±0.6); ash, 19.3 ±0.1; ace yl g oups, 0.3 ±0.0; and p o ein, 15.7 ±0.2. 3.2. E ec o ope a ion condi ions on p o ein ex ac ion yield In o de o e alua e he e ec o he ope a ing condi ions on he p o ein ex ac ion yield, he esul s o scena ios 1, 2, and 3 we e analyzed. The cen al composi e expe imen al designs analyzed he e - ec s o h ee ac o s: namely empe a u e, ime, and he NaOH con- cen a ion. Table 2 shows he expe imen al esul s ob ained o he con en o solid p o ein a e he MAE and he p o ein ex ac ion yield esponses o each expe imen al un and each scena io. As can be app ecia ed in Table 2, he p o ein ex ac ion yield anged be ween 14.1% ( un 19) and 93.7% ( un 11) o BSG, be ween 9.6% ( un 6) and 60.3% ( un 7) o SCG, and be ween 69.4% ( un 16) and 95.4% ( un 15) o kale. A ound he cen al poin o each scena io (Scena io 1: 90ºC, 6.25 min and 0.3 M NaOH ( uns 1, 6, 9, 10, 12, 16 and 18); sce- na io 2: 90ºC, 10 min and 0.55 M NaOH ( uns 9 and 15); and scena io 3: 90ºC, 10 min and 1 M NaOH ( uns 1 and 2)), an a e age p o ein ex ac ion yield o 71.7%, 32.3%, and 90.5% was measu ed o scena ios 1, 2, and 3, espec i ely. Second-o de polynomial equa ions adjus ed he p o ein ex ac ion yield esponses (Eq. (5) o scena io 1, Eq. (6) o scena io 2, and Eq. (7) o scena io 3): P o ein ex ac ion yield = − 175.737 +3.959 T+0.633 +198.404 C−0.021 T2+0.646 TC −225.692 C2 (R2=0.993;R2adjus =0.986)(5) P o ein ex ac ion yield =56.668 −0.866 T−19.379 C +0.501 TC (R2=0.983;R2adjus =0.957)(6) P o ein ex ac ion yield = − 7.823 +1.185 T+0.164 +50.523 C −0.004 T2−14.602 C2 (R2=0.963;R2adjus =0.907)(7) whe e "T" is he empe a u e (ºC), " " is he ime (min), and "C" is he NaOH concen a ion (M). In all he modeling, he alues o R 2 and adjus ed R 2 (Eqs. (1)−(3)), as well as he con idence le els (90%, p <0.05), show a easonable adjus men be ween he expe imen al and p edic ed da a. As obse ed in Eqs. (5)–(7) and Table 2, he mos signi ican e ec is he NaOH concen a ion in he h ee scena ios, his e ec being posi i e o scena ios 1 and 3, and nega i e o scena io 2. In he case o BSG and kale (scena ios 1 and 3), in o de o impo ance, he empe a u e and ime we e also posi i e e ec s, bu he e was a big di e ence be ween hese and he NaOH concen a ion e ec (and e en mo e o BSG). Thus, high alues o NaOH concen a ion could lead o an inc ease in he p o ein ex ac ion yield o BSG and kale. The ime e ec was insigni - ican in SCG (scena io 2). On he o he hand, conce ning he in e ac ions be ween he di e en ac o s (Eqs. (5)–(7) and Fig. 2), a sligh posi i e in e ac ion be ween he empe a u e and he NaOH concen a ion ac o s can be obse ed in scena ios 1 and 2 (BSG and SCG). This end can also be obse ed in he Deleu e al. (2019) s udy, indica ing ha he alkali ex ac ion condi ions gene ally inc ease he p o ein ex ac ion yield by b eaking down he ma ix in which p o eins a e p esen and making he p o ein o ce eals and pseudo-ce eals mo e soluble. In his way, p o eins om ba ley we e also ex ac ed using he alkaline ex ac ion (23ºC, 0.5 M NaOH and 2 h), achie ing 57.1% o p o ein eco e y yield, wi h a p o ein con en o 33 g/100 g aw ma e- ial (Houde e al., 2018). Li e al. (2021) demons a ed ha ul asound alkali ex ac ion imp o es he p o ein yield om BSG e sus con en- ional alkali ex ac ion (86.16 s. 45.71%), a a concen a ion o 110 mM NaOH and 1:15 (w/ ) solid o liquid a io o 20 min unde ul asound ea men . Acco ding o Pa chami e al. (2021), 48% o he ini ial p o ein in BSG was solubilized using a hyd o he mal p e ea men (180 ℃ and 30 min), which is a lowe alue han ha men ioned be o e using alkalis. In his con ex , Con e as e al. (2019) also obse ed a signi ican posi i e e ec when NaOH was added as a sol en , wi h concen a ions up o 0.4 M; poin ing ou ha he solid- o-liquid a io, ex ac ion ime, pH, empe a u e, and alkali concen a ion a e c ucial condi ions, wi h he absolu e amoun o applied alkali being he c i ical ac o . 3.3. E ec o sol en ype on ex ac ion yield In his case, o e alua e he e ec o he sol en ype on he p o ein ex ac ion yield, he expe imen al esul s o scena ios 3 and 4 we e analyzed. The p o ein concen a ion and p o ein ex ac ion yield e- sponses o each expe imen and scena io a e shown in Table 2. As can be seen in Table 2, and compa ing he expe imen al alues o scena ios 3 and 4, he p o ein ex ac ion yield anged be ween 69.4% ( un 16) and 95.4% ( un 15) o alkali ex ac ion and be ween 68.6% Table 2 P o ein composi ion o ex ac ed solids and ex ac ion yields. Run Scena io 1 (BSG- NaOH) Scena io 2 (SCG- NaOH) Scena io 3 (kale-NaOH) Scena io 4 (kale-H 2 O) g/kg RM Yield (%) g/kg RM Yield (%) g/kg RM Yield (%) g/kg RM Yield (%) 1 10.6 69.9 9.9 48.9 1.9 92.4 7.9 68.7 2 3.6 89.7 13.7 29.3 2.9 88.5 7.1 71.7 3 3.6 89.9 12.2 36.8 1.5 94.1 7.0 72.2 4 22.3 36.7 13.8 28.8 5.6 77.8 7.3 71.0 5 27.1 23.1 9.4 51.5 4.0 83.9 6.8 73.0 6 10.2 71.1 17.5 9.6 4.3 82.9 7.9 68.6 7 12.2 65.4 7.7 60.3 2.1 91.8 7.7 69.4 8 24.9 29.5 16.0 17.0 1.9 92.5 7.2 71.3 9 8.4 76.1 12.3 36.1 1.5 94.0 7.4 70.5 10 10.1 71.3 15.4 20.1 6.6 73.6 7.0 72.0 11 2.2 93.7 14.3 26.1 2.9 88.3 12 10.2 71.1 13.6 29.7 7.4 70.6 13 27.6 21.9 9.1 52.7 3.0 87.9 14 8.8 75.0 14.6 24.3 2.9 88.5 15 7.5 78.8 13.8 28.6 1.1 95.4 16 9.4 73.4 13.8 28.3 7.7 69.4 17 23.3 34.0 18 11.1 68.5 19 30.3 14.1 20 2.6 92.6 C. Ba ios e al. Indus ial C ops & P oduc s 186 (2022) 115166 6 ( un 6) and 73.0% ( un 5) o aqueous ex ac ion. The a e age p o ein ex ac ion yield a ound he cen al poin (scena io 3: 90ºC, 10 min and 1 M NaOH ( uns 1 and 2); and scena io 4: 90ºC and 10 min ( uns 2 and 3)), was 90.5% o alkali ex ac ion (scena io 3) and 71.9% o wa e ex ac ion (scena io 4). The p o ein ex ac ion yield esponses we e also adjus ed by he second-o de polynomial equa ion (Eq. (8) o scena io 4): P o ein ex ac ion yield =46.039 +0.437 T+0.594 −0.002 T2 (R2=0.962;R2adjus =0.917)(8) whe e "T" is he empe a u e (ºC), and " " is he ime (min). The alues o R 2 and adjus ed R 2 (Eq. (4)), as well as he con idence le els (90%, p<0.05), also show a easonable adjus men be ween he expe imen al and p edic ed da a in his case. As men ioned abo e and looking a he equa ions (Eqs. (7) and (8)) and Table 2, he mos signi ican posi i e e ec in he case o alkaline ex ac ion is he NaOH concen a ion, and e y sligh ly he empe a u e and ime. On he o he hand, in aqueous ex ac ion, he mos signi ican posi i e e ec is he ime, ollowed by he empe a u e (bo h e y simila ), while e y low e ec s we e ound by compa ing wi h he NaOH concen a ion e ec obse ed o alkaline ex ac ion. This beha io can also be seen in Fig. 2(C-D), espec i ely. This is due o he NaOH ac ing as a acili a ing agen in he ex ac ion p ocess when alkalis a e used. In con as , he e ec is compensa ed o e ime in aqueous ex ac ion, acco ding o Con e as e al. (2019), which indica es ha alkaline ex ac ion gene ally shows highe yields han acid o hyd o he mal ex ac ion. Mo eo e , i is wo h highligh ing ha , by compa ing wi h con en ional ex ac ion me hods, mic owa e-assis ed ex ac ion is able o inc ease he p o ein ex ac ion yield by up o 1.54 imes (Con e as e al., 2019). 3.4. Op imiza ion o ex ac ion condi ions The MAE op imiza ion om h ee AFW (BSG, SCG, and kale) was ca ied ou , maximizing he p o ein ex ac ion yield as he s udied esponse. Thus, he op imal expe imen al condi ions ound by he model o he ou scena ios ( empe a u e, ime, and NaOH concen a ion in he case o alkali ex ac ion) a e included in Table 3. The model was alida ed by pe o ming a con i ma o y expe imen al un in op imal condi ions. As can be obse ed in Table 3, a easonable adjus men o he model was ound o he ou scena ios, since he de ia ions be ween he p edic ed and expe imen al alues we e less han 3% in all ou cases. By compa ing he h ee AFW (BSG, SCG and kale), i can be obse ed ha he bes p o ein ex ac ion yields (92–95%) we e achie ed o BSG and kale when he mic owa e assis ed alkaline ex ac ion was ca ied ou . Howe e , a p o ein ex ac ion yield lowe han 59% was ob ained o SCG using he same alkaline ex ac ion me hod. On he o he hand, by compa ing bo h he hyd o he mal and alkaline ex ac ion me hods o kale, bo h assis ed by he mic owa e echnique; an inc ease in he p o ein ex ac ion yield o up o 22.64% was a ained h ough he alkaline ex ac ion echnique. As desc ibed p e iously, alkaline ex ac ion gene ally shows highe p o ein ex ac- ion yields han acid o hyd o he mal ex ac ion (Con e as e al., 2019). In addi ion, unde hese op imal ex ac ion condi ions, he TPC, TFC, Fig. 2. Su ace esponses o he mos signi ican pa ame e s o each scena io. C. Ba ios e al. Indus ial C ops & P oduc s 186 (2022) 115166 7 an ioxidan capaci y, and o al suga con en we e de e mined (Table 3). As can be app ecia ed, excep o SCG, abou 14–15 g/L o al suga s can be ob ained o bo h BSG and kale aw ma e ials, independen ly o he ca alys (wa e o alkalis) used. Rega ding TPC, simila concen a ions (abou 48–52 mg GAE/g RM) we e a ained o BSG and SCG, while lowe alues we e ob ained o kale (<34 mg GAE/g RM), using bo h hyd o he mal and alkaline ex ac ion echniques. Ne e heless, SCG was he AFW wi h he highes TFC (15.95 mg CE/ g RM), ollowed by BSG and kale (8.68 and 0.98–2.46 mg CE/ g RM, espec i ely). Con- ce ning he an ioxidan ac i i y (DPPH), up o 7.6 and 17.1 mg TE/g RM could be go om BSG and kale by mic owa e-assis ed alkaline ex ac- ion. The e o e, in conclusion, by compa ing he h ee AFW used, BSG could be an in e es ing aw ma e ial o p o ein p oduc ion, as well as o al suga s and phenolic and an ioxidan compounds. On he o he hand, conce ning bo h he hyd o he mal and alkaline ex ac ion me hods pe o med wi h kale, he esul s o o al suga s, TPC, TFC and an ioxidan compounds ob ained (Table 3) show ha hyd o- he mal ex ac ion was able o ge be e esul s o TPC (34.32 s. 20.87 mg GAE/g RM) and TFC (2.46 s. 0.98 mg CE/g RM), as happened o he p o ein ex ac ion yield desc ibed be o e, bu wi h much lowe DPPH alues (1.71 s. 7.57 mg TE/g RM). The o al suga con en was simila (abou 15 g/L) o bo h ex ac ion echniques. Finally, by compa ing he esul s ob ained in his wo k (Table 3) wi h he li e a u e, conside ing BSG o ins ance, simila esul s (90–95%) we e a ained by Qin e al. (2018) using dilu e acid (11,400 mg H 2 SO 4 /g BSG, 121 ◦C o 1 h), o sequen ial alkaline (110 mM NaOH, 1:20 w/ , 50 ◦C and 200 pm) and dilu e acid (1 M H 2 SO 4 , 25 ◦C, 250 pm o 1 h, ollowed by au ocla ing a 121 ◦C o 1 h) ex ac ion, bu lowe alues (64–66%) by hyd o he mal ex ac ion (2.5% w/ , 60ºC, 24 h). A much lowe p o ein ex ac ion yield (48%) and concen a ion (27 g/L) was also achie ed by Pa chami e al. (2021) using hyd o he mal ex ac ion (180 ℃ and 30 min). Du e al. (2020) also ob ained a low p o ein ex ac ion yield (21.4%, 6.8% and 7.2%) using h ee di e en ex ac ion me hods: alkaline (40ºC, 120 min and 0.1 M NaOH), aqueous (40ºC and 120 min), and subc i ical wa e ex ac ion (200ºC and 20 min). Wi h ega d o SCG, simila esul s o p o ein ex ac ion yields (abou 59%) o hose ob ained in his wo k (61%, Table 3) we e ach- ie ed by an acid ex ac ion p ocess (using 0.1 M HCl and 0.1 M NaCl, a 1:12, w/ ) a 4 ºC o 12 h (Ribei o e al., 2021). Mo eo e , he p esence o phenolic (1755.76 µmol GAE/g) and an ioxidan compounds (ABTS: 441 µmol TE/g SCG; FRAP: 611 µmol TE/g SCG) was also de ec ed. This he e o e means ha he p o ein ex ac ion can be sui ably ca ied ou using alkali and acid, which may be due o he s uc u e o he SCG. Samsalee and So ho n i (2021) go a lowe p o ein con en (34%) by ul asonic-assis ed ex ac ion (40% ampli ude, 20 min and pH 11 using 0.7 M Na 3 PO 4 ). Howe e , much highe TPC and DPPH alues (304.81 mg GAE/g RM and 933.92 mM TE/g RM) we e ob ained. As poin ed ou abo e, simila o ela i ely highe p o ein ex ac ion yields a e achie ed in his s udy. Howe e , he bioac i e liquid ex ac s ob ained in his wo k a e cha ac e ized by con aining an app eciable amoun o an ioxidan compounds and ca bohyd a es, gi ing hem g ea e added alue o hei possible comme cial applica ion in he ood, pha maceu ical and cosme ic indus ies. 3.5. Economic e alua ion 3.5.1. In es men and p oduc ion cos s A p elimina y economic s udy compa ed he op imal p o ein e- co e y s a egies om BSG, SCG, and kale was es. Table 4 summa izes he esul s o he Lang Fac o me hod o he ou p oposed scena ios. The o al cos o he equipmen o scena ios 1, 2, and 3, based on NaOH-ex ac ion, is iden ical (153,000 € ), ega dless o he aw ma e ial used because he necessa y equipmen is he same in hese scena ios. Howe e , he cos o scena io 4, which uses wa e as a sol en , is lowe (150,000 € ), because he sol en s o age ank does no equi e co osion- esis an cons uc ion ma e ials, and his scena io does no ha e he NaOH sol en p epa a ion s age be o e MAE. This cos di ec ly a ec s he TIC, 690,000 € (scena io 4) o 710,000 € (scena ios 1, 2, and 3). On he o he hand, he de e mining ac o o es ima e p oduc ion cos s is he aw ma e ial, mainly he amoun o NaOH equi ed in each scena io. Achie ing he lowes cos o he aw ma e ial and he lowes annual p oduc ion cos equi ed, he p oduc ion cos o he p o ein ex ac may hus be educed. So, as shown in Table 4, scena io 4 had he lowes p oduc ion cos (438,000 € /y ) as he ex ac ion is only pe o med wi h wa e . I he NaOH-ex ac ion sce- na ios a e compa ed, scena io 1 had a lowe p oduc ion cos (524,000 € /y ) in compa ison o scena ios 2 and 3 (647,000 € /y ), since scena io 1 needs a lowe concen a ion o NaOH (0.5 M) in con as o scena ios 2 and 3, which use almos 3- imes mo e o NaOH du ing he ex ac ion (1.3 M). O he wise, he p oduc ion cos pe kg o p o ein was associa ed wi h he ini ial p o ein concen a ion o he AFW and wi h he ex ac ion yield achie ed unde op imum ope a ing condi ions. So, scena io 1, whose yield was highe han scena ios 2 and 3, had he lowes p o- duc ion cos s pe kg o p o ein (29.9 € /kg e sus 51.1 –104.6 € /kg). On he o he hand, compa ing he kale-ex ac ion scena ios (3 and 4), he p oduc ion cos depends p incipally on he sol en used. In his case, scena io 4, using wa e as a sol en , had a lowe p oduc ion cos (45.5 € /kg) e sus scena io 3 wi h NaOH sol en (51.1 € /kg). Finally, he minimum selling p ice o he p o ein, shown in Table 4, is he selling p ice om which he plan would begin o be p o i able. As can be seen, he lowes selling p ice o he p o ein ob ained is associ- a ed wi h scena io 1, wi h 51.7 € /kg co esponding o he BSG-NaOH ex ac ion p ocess and a highe yield (14.6 kg p o ein/100 kg DM). In compa ison, he highes p ice was eached in scena io 2 (SCG-NaOH), wi h a selling p ice o 168.6 € /kg, whose o e all ex ac ion yield is he lowes (5.2 kg p o ein/100 kg DM). In any case, hese p ices a e abo e he es ima ed p ices o he sale o p o ein ound in he li e a u e, indica ing ha he p oposed p ocesses a e no p o i able. The ma ke p ice depends on he aw ma e ial and he p o ein p ope ies (Bake and Cha l on, 2020). Fo example, Munee e al. (2021) es ima ed ha he p o ein ma ke p ice a ied om 2 o 15 € /kg. Howe e , his p ocess could p o e p o i able i no only he p ecipi a ed p o ein is aken in o accoun . The ex ac s ob ained a e ex ac ion con ain signi ican Table 3 Cha ac e iza ion o op imal ex ac s. Scena io 1 (BSG- NaOH) Scena io 2 (SCG- NaOH) Scena io 3 (kale- NaOH) Scena io 4 (kale-H 2 O) Tempe a u e (ºC) 110 113 109 102 Time (min) 9.98 3.33 14.93 15.30 NaOH concen a ion (M) 0.50 1.30 1.29 0.00 P o ein ex ac ion yield (%) 93.99 61.17 96.55 72.78 Con i ma o y expe imen al p o ein ex ac ion yield (%) 92.05 58.99 95.23 72.59 To al suga s (g/L) 13.84 5.50 14.96 15.20 TPC (mg GAE/g RM) 48.42 52.08 34.32 20.87 TFC (mg CE/ g RM) 8.68 15.95 2.46 0.98 DPPH (mg TE/g RM) 17.10 2.09 1.71 7.57 C. Ba ios e al. Indus ial C ops & P oduc s 186 (2022) 115166 8 amoun s o suga s and an ioxidan compounds, demons a ing an adequa e an ioxidan capaci y. Fo example, he ex ac om scena io 1 has a suga con en o 13.84 g/L, a TPC o 48.42 mg GAE/g RM, a TFC o 8.68 mg CE/g RM, and a DPPH an ioxidan capaci y o 17.10 mg TE/g RM. These concen a ions would posi i ely a ec he selling p ice o he bioac i e ex ac s ob ained. In his way, he p o i abili y o he p ocess would be signi ican ly imp o ed. 3.5.2. Sensi i i y analysis Based on he economic e alua ion, a sensi i i y analysis was pe - o med o analyze he in luence o he mos c i ical pa ame e s ha could a ec he NPV (Fig. 3). Fo he e alua ed scena ios, he key pa- ame e s ha signi ican ly a ec he NPV a e he p o ein selling p ice and he o al di ec cos s. Among he aw ma e ials cos s, hose o he AFW and wa e a e insigni ican in he NPV a ia ion in he scena ios e alua ed (Fig. 3). On he con a y, he a ia ion in he cos o NaOH a ec s scena ios 1, 2, and 3 (NaOH-ex ac ion). The NPV can a y by up o 360,000 € when he cos o he NaOH changes by 50% (inc emen al and dec emen al) (Fig. 3. C). On he o he hand, scena io 1 (BSG-NaOH) is he leas a ec ed by he a ia ion in he cos o he NaOH, since he NPV only dec eases o 140,000 € when he cos o he NaOH inc eases by 50%. Conce ning he plan p o i s, he only income is gene a ed om selling he p o ein, while he sensi i i y analysis demons a es ha he NPV alue is suscep ible o changes in his p ice. Fo example, a 50% inc ease in he p o ein sale p ice can inc ease he NPV by 1280,000 € o 1675,000 € (Fig. 3. B-D). Howe e , he inc emen in he p o ein p ice is un easible om an economic poin o iew, and i is necessa y o educe he selling p ice in o de o be compe i i e. Fo example, in he case o scena io 1 (BSG-NaOH), which has he lowes selling p ice (51.7 € /kg) (Table 4), he sensi i i y analysis shows ha i he p o ein we e o be sold wi h a compe i i e p ice (15 € /kg), he plan losses would be abo e 2100 k € . Some esea che s ha e demons a ed he economic iabili y o he MAE echnology o o he applica ions (Zhang e al., 2014; Fe n´ an- dez-Delgado e al., 2022). The e o e, an al e na i e o ob aining a iable and compe i i e ex ac ion p ocess could be o op imize he MAE p o- cess o ob ain ex ac s en iched no only in p o eins, bu also in o he bioac i e compounds o in e es o ood and biomedical applica ions. As seen be o e, hese ex ac s con ain a signi ican suga concen a ion and an ioxidan compounds, p o ing a sui able an ioxidan capaci y. In his way, he p oduc ion cos s could dec ease signi ican ly and he selling p ice o he whole p ocess could be compe i i e in he ood and pha maceu ical ma ke . Table 4 Economic e alua ion o he p oposed scena ios. P ecipi a ed P o ein PCE TIC P oduc ion Cos Minimum Selling P ice Yield Flow Uni s kg/100 kg DM kg/h € € € /yea € /kg € /kg Scena io 1 (BSG-NaOH) 14.6 2.2 153,000 710,000 524,000 29.9 51.7 Scena io 2 (SCG-NaOH) 5.2 0.8 153,000 710,000 647,000 104.6 168.6 Scena io 3 (kale-NaOH) 10.6 1.6 153,000 710,000 647,000 51.1 82.3 Scena io 4 (kale-H 2 O) 8.0 1.2 150,000 690,000 438,000 45.5 82.9 Fig. 3. Sensi i i y analysis o he p oposed scena ios. (A) Scena io 1: BSG +NaOH; (B) Scena io 2: SCG +NaOH; (C) Scena io 3: kale +NaOH; (D) Scena io 4: kale +H 2 O. C. Ba ios e al. Indus ial C ops & P oduc s 186 (2022) 115166 9 4. Conclusions This s udy con i ms ha mic owa e-assis ed hyd o he mal and al- kali ex ac ion is a sui able echnology o he e icien eco e y o bioac i e compounds om he ag i- ood was es es ed (BSG, SCG and kale s ems). Technically and economically, mic owa e-NaOH ex ac ion om BSG p o ides he bes al e na i e o ob aining ex ac s o com- me cial in e es en iched in p o ein (p o ein eco e y yield o 94%), o al suga s and an ioxidan compounds. Howe e , hyd o he mal mi- c owa e ex ac ion om kale s ems could become a p omising p ocess ha combines a no el was e in a bio e ine y con ex , which con ains an app eciable p o ein concen a ion (15.7% w/w) wi h a wa e -based cleane sol en ope a ing unde mild p ocess condi ions. CRediT au ho ship con ibu ion s a emen C is ina Ba ios: In es iga ion, Me hodology, W i ing −o iginal d a . Ma ina Fe n´ andez Delgado: In es iga ion, Me hodology, W i ing −o iginal d a . Juan C. L´ opez-Lina es: In es iga ion, Me h- odology, W i ing −o iginal d a , Supe ision. Ma ía Te esa Ga cía- Cube o: Concep ualiza ion, Supe ision, W i ing −o iginal d a . M´ onica Coca: Concep ualiza ion, Fo mal analysis, Supe ision. Susana Lucas: Concep ualiza ion, W i ing − e iew & edi ing, P ojec adminis a ion. Decla a ion o Compe ing In e es The au ho s decla e ha hey ha e no known compe ing inancial in e es s o pe sonal ela ionships ha could ha e appea ed o in luence he wo k epo ed in his pape . Acknowledgmen s The au ho s acknowledge he inancial suppo om he Spanish Minis y o Science and Inno a ion (p ojec PID2020–115110RB-I00/ AEI/10.13039/501100011033), and he Jun a de Cas illa y Le´ on (UIC 320, VAG028G19, CLU 2017–2109, CL-EI-2021–07). Re e ences A abani, A.E., Al-Muh aseb, A.H., Kuma , G., Sa a aled, G.H., Aslam, M., Khan , H.A., Saidg, Z., Mahmoudh, E., 2019. Valo iza ion o spen co ee g ounds in o bio uels and alue-added p oduc s: Pa hway owa ds in eg a ed bio- e ine y. Fuel 254, 115640. Aqua all, 2017, Supply se ice ees. h p://aqua all.es/wp-con en /uploads/2017/06/ a i as_agua_2017.pd (accessed 17 Decembe 2021). Bake , P.W., Cha l on, A., 2020. 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