Redalyc.EFFECT OF COOKING, ANNEALING AND STORAGE ON STARCH DIGESTIBILITY AND

14 Pages·2015·3.18 MB·English

Revista Mexicana de Ingeniería Química
ISSN: 1665-2738
[email protected]
Universidad Autónoma Metropolitana Unidad
Iztapalapa
México
de la Rosa-Millán, J.; Agama-Acevedo, E.; Osorio-Díaz, P.; Bello-Pérez, L.A.
EFFECT OF COOKING, ANNEALING AND STORAGE ON STARCH DIGESTIBILITY AND
PHYSICOCHEMICAL CHARACTERISTICS OF UNRIPE BANANA FLOUR
Revista Mexicana de Ingeniería Química, vol. 13, núm. 1, abril, 2014, pp. 151-163
Universidad Autónoma Metropolitana Unidad Iztapalapa
Distrito Federal, México
Available in: http://www.redalyc.org/articulo.oa?id=62031166012
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Revista Mexicana de Ingeniería Química deRInevgiesntaierM´ıaexQicua´ınmaica
AcademiaMexicanadeInvestigaci´onyDocenciaenIngenier´ıaQu´ımica,A.C.

Vol. 13, No. 1CO(N2T0E1N4I)D1O5 1-163

Ingeniería de alimentos Volumen 8, número 3, 2009 / Volume 8, number 3, 2009 ISSN1665-2738 Volumen13,Nu´m1ero1,Abril2013

EFFECTOFCOOKING,ANNEALINGANDSTORAGEONSTARCH

DIGESTIBILITYANDPHYSICOCHEMICALCHARACTERISTICSOFUNRIPE
213 Derivation and application of the Stefan-Maxwell equations 1
BANANAFLOUR
(Desarrollo y aplicación de las ecuaciones de Stefan-Maxwell)
EFECTODEL CSOtephCenI WMhitaIkEer NTO,ANILLADOYALMACENAMIENTOENLA
DIGESTIBILIDAD YLASCARACTERI´STICASFISICOQUI´MICASDEHARINADE
Biotecnología / BiotechnologPy LA´TANOVERDE
J.delaR24o5 sMao-dMelaidlloa´ dne, lEa .bAiodgeagrmadaac-iAónc eenv ebidorore,aPct.orOess oder ilood-oDs ´ıdaez h∗idarnocdarbLu.rAos .toBtaelelsl od-ePl ep´erterózleo
intemperizados en suelos y sedimentos
InstitutoPolite´cnicoNacional,CentrodeDesarrollodeProductosBio´ticos. Km. 6.5Carr. Yautepec-Jojutla,Col.
(Biodegradation modeling of sludge bioreactors of total petroleum hydrocarbons weathering in soil
SanIsidro,C.P.62731Yautepec,Morelos,Me´xico.
and sediments)
S.RA.e Mceediivnea-dMoOrecntoo, bS.e Hru7er,ta2-O0c1h3oa;, AC.cAc. eLupctheod-CNonostvanetimnob, Le.r A5g,ui2le0ra1-V3ázquez, A. Jiménez-
González y M. Gutiérrez-Rojas
Abstract 259 Crecimiento, sobrevivencia y adaptación de Bifidobacterium infantis a condiciones ácidas
Theeffectofcooking(C)unripebananafruitsatdifferenttimes(5,15and25min),followedbyannealing(ANN)
(Growth, survival and adaptation of Bifidobacterium infantis to acidic conditions)
and annealing + storage (ANN+S) were evaluated. Cooking of unripe banana fruit for longer times (15 and 25
L. Mayorga-Reyes, P. Bustamante-Camilo, A. Gutiérrez-Nava, E. Barranco-Florido y A. Azaola-
min) decreases the RS content, but increases the SDS fraction. Granular aggregates were produced, which could
Espinosa
be formed by partially gelatinized granules. ANN and ANN+S increased the RS content, while the SDS value
265 Statistical approach to optimization of ethanol fermentation by Saccharomyces cerevisiae in the
didnotchange. ThepastingbehaviourofANNandANN+Sshowedlowviscositywithoutbreakdownorsetback
duetotherestrictedamyloseprleeseancceh oinf Vga,lfwor®hi zceholiwte NasaAh igherinflourswithANN+S.TheANNandANN+Sincreased
thegelatinizationtempera tur(eOsptiwmihzaicleiónt hesetadaínstnicea adele lad fearnmdentsatcoiórne edtansóalimcap dlee Ssacschhaorwomeydcesa cnerienvicsiraee aesne priensentchiae dce rystallinitylevel
duetoreorganizationofthezgeroalitna uVlaalfrors®t rzueocltitue rNeaAc)o mparedwithnativeandcookingtreatedsamples. Itispossibleto
combine different treatmentsG.t Ioneim-Shoizduikfaywat,h He. As. tVaerlacshco-dBiegderásnt,i Gb.i Fli.t Gyutoiéfrreuzn-Lróippeez abnda Hn.a Hnearnflánoduezr-,Sádncuheez to that changes in the
granularconformationwe reproduced,whichdecreaseitsabilitytoswellandtogelatinize.
Ingeniería de procesos / Process engineering
Keywords: annealing;starchdigestibility;bananaflour;resistantstarch.
271 Localización de una planta industrial: Revisión crítica y adecuación de los criterios empleados en
Resumen
esta decisión
Seevaluo´,enfrutosdepla´tanoverde,elefectodelacoccio´n(C)adiferentestiempos(5,15y25min)seguidode
(Plant site selection: Critical review and adequation criteria used in this decision)
annealing(ANN),yannealing+almacenamiento(ANN+A).Lacoccio´ndelosfrutosdurantetiemposprolongados
J.R. Medina, R.L. Romero y G.A. Pérez
(15 y 25 min) disminuyo´ el contenido de almido´n resistente (AR), pero incrementaron la fraccio´n de almido´n

de digestio´n lenta (ADL). Se produjeron agregados granulares, los cuales pueden estar formados por gra´nulos

parcialmente gelatinizados. El ANN y ANN+A incrementaron el contenido de AR, mientras que el ADL no

cambio´. Laviscosidadde pastasconelANNyelANN+Afueronbajas,sinrompimientogranularore-asociacio´n,
debido a restriccio´n en el hinchamiento de los gra´nulos y la baja lixiviacio´n de amilosa, la cual fue mayor en las
muestrastratadasconANN+A.ElANNyelANN+Sincrementaronlastemperaturasdegelatinizacio´n,as´ıcomosu
cristalinidad,debidoalareorganizacio´ndelaestructuragranularcomparadaconlasmuestrasnativasyconcoccio´n.
Esposiblecombinardiferentestratamientosparamodificarladigestibilidaddelalmido´ndelpla´tanoverde,debidoa
loscambiosqueseproducenenlaconformacio´ngranular,loscualesdisminuyensuhinchamientoygelatinizacio´n.
Palabrasclave: anillado;digestibilidaddelalmido´n;harinadepla´tano;almido´nresistente.
∗Correspondingauthor.E-mail:[email protected]
Tel.[phone],Fax[phone]
PublicadoporlaAcademiaMexicanadeInvestigacio´nyDocenciaenIngenier´ıaQu´ımicaA.C. 151
delaRosa-Milla´netal./RevistaMexicanadeIngenier´ıaQu´ımicaVol. 13,No. 1(2014)151-163
1 Introduction
starch polysaccharides, such as dietary fiber (14.5%)
(Jua´rez-Garc´ıaetal., 2006). Thenutritionalfractions
ofstarchaswellasthepastingandthermalproperties
Starch is the main carbohydrate in the human diet
of banana flour are crucial for food application. The
and has been widely used as an ingredient in the
objectives of this study were to determine the impact
food industry. Nowadays, consumers are in search
ofANNandSontheSDSandRSfractionsofunripe
of products that can improve their health and well-
banana flour, and to evaluate their physicochemical
being. It is well known that unripe banana starch
characteristics.
has a very low digestion rate when raw (Faisant
et al., 1995). And that this characteristic has a
beneficial effect on colonic health. According to
2 Materials and methods
its rate of digestion and glucose release, starch has
been classified into three fractions: rapidly digestible
Unripe bananas (Musa paradisiaca L.) were
starch (RDS), slowly digestible starch (SDS) and
purchased at the local market of Cuautla, Morelos,
resistantstarch(RS).Afteringestion,theRDSfraction
Mexico. Green fruits without yellow spots and from
causes a sudden increase in blood glucose level, the
25to30cminlengthwereobtained.
SDS is hydrolyzed completely in the small intestine
at a lower rate compared to the RDS; and the RS
is the portion that cannot be digested in the small 2.1 Cookingofgreenbananafruit
intestine,butratherisfermentedinthelargeintestine
Bananafruitswereseparatedinfourgroupsofsimilar
(Englyst et al., 1992). However, it is important to
weight; three of those groups were separated for
keep in mind that when the unripe fruit is cooked,
cooking treatment by submersion in a boiling water
as occurs in many countries of South America and
Africa, its native RS is rendered digestible. Different bath(100◦C),thefirstgroupfor5min,thesecondfor
15minandthethirdfor25min. Afterthetime,fruits
methods and processing conditions have been used
were removed from the water bath and submerged
to increase or modify starch fractions; annealing
in an ice bath (3-4 ◦C) until the temperature in the
(ANN) and storage (S) are hydrothermal treatments
center of the fruit reached 20 ◦C; temperature profile
that have proven to increase SDS and RS. During
ANNstarchgranulesinexcesswater(>60%w/w)are duringthecoolingstepwasdeterminedusingadigital
thermometer(Radioshack,USA),thefourthuncooked
incubated at a temperature above the glass transition
groupwasusedascontrol.
temperature(T )butbelowtheonset(T )temperature
g o
ofgelatinizationinagivenperiodoftime(Hooverand
Vasanthan1994;TesterandDebon2000). Depending 2.2 Flourpreparation
on the source of the starch, the susceptibility to
enzyme hydrolysis increases, decreases, or remains The groups of cooked and uncooked green banana
unchanged after ANN (Hoover and Manuel 1996; werepeeledandsliced(1cmthick),thenwerewashed
Jacobs and Delcour 1998; Waduge et al., 2006). with a citric acid solution (0.5 g/L), afterwards were
Otherwise, different S conditions have been used to driedinaconvectionovenat40◦Cfor24hr.Thedried
promote retrogradation of starch compounds mainly slices were grounded with a manual grinder (Mapisa
to increase the RS fraction. Incubation of starch gels Internacional S.A de C. V., Me´xico, D.F.) until pass
at low temperatures (refrigeration) for a set period meshn◦50.
of time promotes reorganization of leached amylose
chains from starch granules during gelatinization. 2.3 Chemicalanalysis
However, the RS and SDS in the granular starch
produced by ANN and/or S are not heat stable. The Moisture content was determined by gravimetric
lack of thermal stability of SDS and RS represents a heating (130 ◦C for 2 h) using 3 g of flour.
drawback of functionality as a food ingredient. The Ash and protein were analyzed according to AACC
use of banana flour instead of isolated starch has methods08?01and46?13,respectively(AACC2000).
severaladvantagesbecausesomecomponentspresent Total starch (TS) was determined by the Gon˜i et
in the flour can help to promote thermal stability al. (1997) method; in brief, 50 mg of sample
and decrease the rate of enzymatic hydrolysis, and were dispersed in 2 M KOH during 30 min to
also be a source of antioxidant compounds such as hydrolyze starch, then the samples were incubated
polyphenols(Ovando-Mart´ınezetal.,2008),andnon- with amyloglucosidase (Roche, No. 102857, 60 ◦C,
152 www.rmiq.org
delaRosa-Milla´netal./RevistaMexicanadeIngenier´ıaQu´ımicaVol. 13,No. 1(2014)151-163
45 min, pH 4.75), and glucose was determined using at 50, 65, 80 and 95 ◦C in sealed cap tubes for 30
the glucose oxidase peroxidase assay GOD-POD minwithconstantmagneticstirring,tubeswerecooled
(Sera-Pak(cid:13)R Plusglucose, BuenosAires, Argentina). at room temperature and centrifuged at 2000 × g for
Glucose concentration (µg/mL) was determined by 10 min. The supernatant (1.0 mL) was withdrawn,
linear regression analysis. TS were calculated as and amylose content was determined as described by
glucose (mg) × 0.9; potato starch was used as a HooverandRatnayake(2004).AMLwasexpressedas
control. percentageofamyloseleachedper100gofdryflour.
2.4 Annealingandstorage 2.8 X-raydiffraction
Banana flours were weighed into hermetic glass X-ray diffraction patterns were obtained using an
containers. Moisture content of flour was carried to AdvanceD8diffractometer(Bruker,Coventry,UK)at
70% by adding the appropriate amount of distilled 35 kV with CuK α radiation (1.542 Å). The samples
water. The containers were tight sealed, kept for were scanned in the angular range 3-37 ◦ (2θ). The
24 h at room temperature, and then were annealed crystallinity percentage (% C) was determined from
(A), incubating the containers at 65 ◦C for 24 h in thediffractogramcalculatingtheareacorrespondingto
a convection oven. Afterwards the containers were thecrystallinepeaksAp;fromthedifferencebetween
opened, and the flour samples were dried at 40 ◦C theareaunderthecurveandtheareaoftheamorphous
for 24 h. After ground and passed through a 50 halo, the total area under the curve (At), and the
mesh screen, annealed flours were kept into hermetic instrumental noise (N) according to the following
plastic bags until analysis. For storage treatment (S), equation(Rodr´ıguez-Garc´ıa,1995):
aftertheincubationperiodat65◦C,tightsealedglass
containers were kept in refrigeration at 4 ◦C for 7 %C = Ap (1)
days,afterwardstheflourswerevacuumdriedatroom At−N
temperature(25◦C)andwerekeptinplasticbagsuntil
The amorphous halo was determined with the
analysis.
amorphous component of starch obtained with an
extraction procedure reported elsewhere (Bogracheva
2.5 Polarizedlightmicroscopy etal.,2001).
Birefringence of native, ANN, and ANN+S starch
granules was observed under polarized light with 2.9 Starchdigestibility
a light microscope (Leitz-Wetzlar, Germany) The
2.9.1Ungelatinizedflour
images were recorded at the same magnification
(100X)forallfloursamples(1.0%floursuspension). In vitro starch digestibility was determined following
the method described by Englyst et al. (1992) with
2.6 Scanningelectronmicroscopy(SEM) slight modifications. Flours (800 mg) were hydrated
with 8 mL of distilled water; pepsin (52.1 mg) was
ForSEMstudies,thesamplesofnative,C,ANN,and dispersed in water (10 mL) and was added to each
ANN+Sflourswerefixedtoaconductivedoubleglued tube, which was incubated in a shaking water bath
carbontape;afilmpiecewasmountedonanaluminum (37 ◦C, 200 strokes/min) for 30 min. At 20 min
stub. Sampleswerecoveredinametalionizer(JEOL) of incubation, porcine pancreatic ?-amylase (1 g)
with a 50 nm thick gold layer; afterwards sample was dispersed in water (6.7 mL), and centrifuged at
was deposited under vacuum in a JEOL JSMP 100 1500 × g for 12 min. The supernatant (4.6 mL)
(Tokyo, Japan) electron microscope. All samples was transferred to a beaker, and amyloglucosidase
wereexaminedusinganacceleratedvoltageof15kV (0.26 ml) and invertase (0.33 mL) were added to
(Viveros-Contrerasetal.,2013). the solution. This enzyme solution was freshly
prepared for each digestion. After 30 minutes of
protein digestion, 10 mL of 0.5M sodium acetate
2.7 Amyloseleaching(AML)
buffer (pH 5.2) were added to each test flask. The
Todetermineamyloseleachingduetoheating,25mg enzyme solution (1 mL) and 5 glass beads (1 cm
of flour (d.s.b.) were weighted, and mixed with 10 diameter) were then added into each tube, which
mL of deionized water, and then mixture was heated was incubated in a shaking water bath (37 ◦C, 200
www.rmiq.org 153
delaRosa-Milla´netal./RevistaMexicanadeIngenier´ıaQu´ımicaVol. 13,No. 1(2014)151-163
strokes/ min). Aliquots (0.5 mL) were taken at 1 2.12 Statisticalanalysis
minute intervals between samples and mixed with 4
One-way analysis of variance (ANOVA) at
mL of 80% ethanol. The glucose oxidase-peroxidase
significancelevelof5%(α=0.05)wasappliedtodata
reagent measured the hydrolyzed glucose content.
and when statistical differences were found, Tukey’s
Starch classifications based on the rate of hydrolysis
test of multiple comparisons was applied analysis
were: rapidly digestible (digested within 20 min)
was done using the statistical program Sigma-stat
starch (RDS), slowly digestible (digested between 20
(SYSTATSoftware2005).
and 120 min) starch (SDS) and resistant starch (RS)
(undigestedafter120min).
3 Results and discussion
2.9.2Gelatinizedsample
3.1 Chemicalanalysis
The native, ANN, and ANN+S flours (800 mg) and
water (8 mL) were added to Erlenmeyer flasks. The The total starch content of native and thermal treated
flasksweresealedtoavoidwaterloss,andthecontents floursdidnotshowsignificantdifferences,withvalues
were mixed by manual stirring for 1 min. The flasks around 75%. A similar total starch content has been
were heated in a boiling- water bath for 30 min with reportedinunripebananaflourwithouttreatmentand
shake at low speed (100 strokes/min). After heating, is used for preparation of spaghetti (73.7% and for
the flask was placed in a water bath at 37 ◦C for 10 preparation of fiber-rich powder (76.8%) (Ovando-
mintoequilibratethetemperature. Sameprocedureof Mart´ınezetal.,2008;Rodr´ıguez-Ambr´ızetal.,2008).
enzymaticdigestion(above)wasfollowed.
3.2 Polarized light and scanning electron
microscopy
2.10 Rapidviscosityanalysis
The raw unripe banana flour (figs. 1A and 1B)
The paste viscosities of treated and untreated green
showed intact starch granules with characteristic
banana flour were determined by using a Rapid
birefringence. Thispatternshowsthatthepreparation
Visco Analyzer (RVA) (Newport Scientific Inst.,
of the flour did not affect the main component of the
Warriewood, Australia). The flour slurry (7.0% w/w,
pulp.Othercomponents(proteinandfiber)arepresent
d.s.b)washeatedfrom50to95◦Cfor3.5min,heldat
intheflour(Fig.1A).Thebananastarchgranulesare
95◦Cfor5min,cooledto50◦Cfor3.5minandthen
elongated with lenticular shape, characteristics that
heldat50◦Cfor4min.
werereportedinisolatedbanana(Espinosa-Sol´ısetal.,
2009; Bello-Pe´rez et al., 2005). At longer cooking
2.11 Differentialscanningcalorimetry times (Fig. 1C-1F), aggregates were observed, and
they were more evident at the longest cooking time
The thermal properties of starch were studied (25 min). The aggregates reveal that they were
using a differential scanning calorimeter (DSC, TA formed of starch granules that were not completely
Instruments, model 2010, New Castle, NJ, USA) gelatinized due to the presence of birefringence (Fig.
previously calibrated with indium. Samples (2 mg, 1D). A decrease in birefringence was observed when
d.s.b)wereweighedinanaluminumpanand7mLof the cooking time increased (Fig. 1F). The presence
deionizedwaterwasadded.Thepanwassealedtightly of protein and components of the fiber protected
andallowedtostandfor1hbeforeanalysis.Anempty the starch granules, preventing the gelatinization of
aluminumpanwasusedasreference. Thesamplewas the starch granules (Debet and Gidley 2007). The
subjected to a heating program ranging from 20 to annealing treatment in the raw unripe banana flour
120 ◦C at a heating rate of 10 ◦C/min. Onset (To), (Raw+ANN) (Fig. 2A) produced changes in the
peak(Tp),conclusiontemperature(Tc),andenthalpy shape of the starch granules; some starch granules
of gelatinization (∆H) were obtained directly from maintained an elongated shape but they appeared as
the data analysis using the software TA Instruments swollen granules. The birefringence characteristics
Universal Analysis 2000 for Windows version 3.2. continued, indicating the order of starch components
For starch retrogradation samples were stored at 4 in the granular structure. The sample was cooked
◦C for 7 days and then re-scan as above. Triplicate for 15 min and annealed (15+ANN), which did not
measurementsweredoneforeachsample. change the morphology of the aggregates, but the
154 www.rmiq.org
delaRosa-Milla´netal./RevistaMexicanadeIngenier´ıaQu´ımicaVol. 13,No. 1(2014)151-163
birefringenceappearedtodecrease(figs.2Cand2D). to the fact that ANN produces a granular re-ordering
A similar pattern was found in the same sample with andSproducesaretrogradationofstarchcomponents
additionalstorage(15+ANN+S),whereanincreasein (Kruegeretal.,1987;TesterandMorrison1990).
the birefringence was detected. This pattern is due

A) B)
C) D)
E) F)

Fig. 1. Unripebananafloursamples;A,CandE,electron scanningmicroscopyimagesofRawunripebananaflour,
cookedfor15and25minrespectively;B,DandFpolarizedlightmicroscopyimagesofRawunripebananaflour,
andcookedfor15minand25minrespectively.
www.rmiq.org 155
Figure 1. Unripe banana flour samples; A, C and E, electron scanning microscopy images
of Raw unripe banana flour, cooked for 15 and 25 min respectively; B, D and F polarized
light microscopy images of Raw unripe banana flour, and cooked for 15 min and 25 min
respectively. Arrows indicate starch granules.
delaRosa-Milla´netal./RevistaMexicanadeIngenier´ıaQu´ımicaVol. 13,No. 1(2014)151-163
A) B)
C) D)
E) F)
Fig. 2. Thermaltreatedbananaflours;A,CandE,electronscanningmicroscopyimagesofRaw+ANN,15+ANN,
and 15+ANN+S respectively; B, D and F light microscopy images of Raw+ANN, 15+ANN, and 15+ANN+S
respectively.
Figure 2. Thermal treated banana flours; A, C and E, electron scanning microscopy images of
Raw+ANN, 15+ANN, and 15+ANN+S respectively; B, D and F light microscopy images of
Raw+3A.3NNA, m1y5l+oAseNleNa,c hanindg 15+ANN+S respectively. AThrirsopwarsa minedteirciasteim sptoarrtcanht ginratnheulfeusn.c tionality and
the starch digestibility of unripe banana flours. At
Heating treatment such as cooking and annealing lowheatingtemperatures(50and65◦C)theamylose

produces amylose leaching from the starch granules. leachingvalue(Fig.3)wassimilarfortherawunripe
156 www.rmiq.org
A)
A)

delaRosa-Milla´netal./RevistaMexicanadeIngenier´ıaQu´ımicaVol. 13,No. 1(2014)151-163
A)
A)

d

28.0%

c
  30.8%

b
  34.2%

d

a
  3285..02%%

c
  30.8%

b
  34.2%

a
  35.2%

B)

B) a)
a)

B) B)

d
  28.5%

c

40.4%

b
 d
  3284..54%%

a
 c
  35.2%

40.4%

b
  34.4%

a
  35.2%

b)
Fig.4.X-raydiffractionpatternsofunripebananaflour

b) underdifferenttreatments: A)Effectofcookingtime,

Fig. 3. Amylose leaching of thermal treated unripe a) Raw unripe banana flour, cooked for: b) 5 min, c)

Fflioguurr e( ◊b3).a, Ancomaonyklaeodsfl ef ooleru a5rcs hm;iniAgn o)(□fR )th,a e1wr5m mauln itnrr ei(apΔte)e da bnuadn rni2pa5en mbaainnfl ao(nXau )rf lro(eu(cid:5)spr)se,;c Actiov) eoRlyFEka;wife gfB deuu)crn teRr ioap 4fwe. c bXuoano-nrr1kaianpi5ynae g dm itfiimfnraeca, tnaio)d nR dap)wat2 tue5rnnrmsip oein fb ;uaBnnar)inpaEe fffbloaeuncrat,n coao foflkaoenudrn feuoanrdl: iebnr) g d5,i fmafe)irnRe, ncat) w t1re5a mtminen atns:d Ad))
baFniagnuarf efo l3or.u 5Ar (mm◊y),il oncsoe(o (cid:3)kleea)dc, hf1oin5rg 1 mo5f m itnhien(r (m∆○a))l, at1rn5ea+dtAe2dN 5uNnm r(i+pi)en abn(adXn a1)n5,a+ rfAeloNsupNrse+; cSAt )(i XvRe2)a wl5rye smu;pneirncipt;i evB eb)lay nE.a ufnfnae rcitp oef bananneaanliangfl, oa)u rR,abw) uRnariwpe+ bAanNanNa ,flco)ur1, 5b+) ARaNwN+A,NanNd, c) 15+ANN,
flour B(◊)),R coaowkeud nforri p5e mbina n(□a)n, a15fl moiun r(Δ((cid:5)) )a,ndc o25o kmeind (fXo)r re1s5pemctiivnelya(;n◦ FdB)i ,g)d uR)r a2ew 54+ .u AnXrNdi-prN)ea y 2r e5ds+ipffeArcatNcivtiNeolny, .pr eatstperencs toivf eulnyr.ipe banana flour under different treatments: A)

  banan1a5 f+louAr N(◊)N, co(o+k)eda fnord 115 5m+inA (○N), N15++ASN(NX ()+,) raends p15e+cAtiNvNe+lyS. (X ) rEesfpfeecctti voefl yc.o oking time, a) Raw unripe banana flour, cooked for: b) 5 min, c) 15 min and d)
25 min; B) Effect of annealing, a) Raw unripe banana flour, b) Raw+ANN, c) 15+ANN,

  and d) 25+AbNuNt aretspheicgtihveelry.t emperature (80 ◦C), ANN and mostly

banana flour to that cooked for 5 and 15 min, but a ANN+S decrease the amount of leached amylose.
higher amylose leaching value was obtained at 65 ◦
 C However, at the highest temperature in the test (95
inthesamplecookedfor25min. Cookingforalong ◦C) no difference was detected between the samples
periodoftimeproducedhigherstarchdisorganization with ANN and ANN+S. However, a plateau was not
and when this unripe banana flour is heated, a higher observed in cooked for 15 min, 15 + ANN, and 15
amount of amylose is leached. The test at 80 ◦C + ANN + S samples. This indicates that amylose
producedtwokindsofbehaviorinthesamples; those leachingfromthestarchgranulecontinuedafter80◦C,
with a minimum heating treatment (raw and cooked andperhapsnomoreamylosewillbeapartouttothe
for5min)hadthehighestamountofleachedamylose continuousphasebecausethe“ghosts”starchgranules
andthosewithalongercookingtime(15and25min) keep amylopectin and perhaps some lineal chains. It
had the lowest amount (around 18%). Heating at isverydifficulttobrokethe“ghosts”andliberatesthe
a higher temperature (95 ◦C) produced a plateau of starchcomponents; highshearratecouldproducethe
leachedamylosecontent(around34%)fortherawand completeleachingoflinealchains(amyloseandsome
thesamplescookedfor5minutesandthosecookedfor external long chains of amylopectin) from “ghosts”
a longer time (15 and 25 min) increased, reaching (Zhang et al., 2013). Similar results have been
a value of approximately 27%. The microscopy found in native starches, as shown by Tester and
study showed the presence of aggregates when the Morrison (1990) and Radosta et al. (1992). Some
cooking time increased; the aggregates could retard authors have attributed this pattern to the interaction
the amylose leaching when the flour was heated betweenamyloseandamylopectinchains(Hooverand
in water. ANN and ANN+S treatments produced Vasanthan1994;TesterandDebon2000),andalsoto
a decrease in the amylose leaching (Fig. 3B). At the presence of aggregates with a higher order in the
lower temperature of the test (50 and 65 ◦C) there sampleswithANNandANN+S,asevidencedbythe
was no difference in the amylose leaching content, microscopystudy,whichmayexplainthispattern.
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3.4 X-raydiffraction importantinstarchdigestibilitybecauseitcouldaffect
therateatwhichenzymesdegradethestarchgranules
(HanandBeMiller,2007).
The raw unripe banana flour and that cooked for
different times showed a B-type X-ray diffraction
pattern (Fig. 4A). Raw unripe banana flour and the 3.5 Starchdigestibility
5 min cooked sample showed a similar crystallinity
level. Cookingfor15and25minproducedadecrease The starch fractions after enzymatic digestion of
in the crystallinity, indicating disorganization of the the ungelatinized and gelatinized samples are shown
starch components, as evidenced in the microscopy in Table 1. The raw unripe banana flour showed
study, thermal analysis and pasting behavior. The high resistant starch (RS) content and the 5 min
change in the crystallinity level can be following in cooking time of the fruit did not affect this content.
the main peak at 2θ = 17◦. The wideness of this At longer cooking times, an important decrease in
peak increased at longest cooking time due to higher RS amount and increase in slowly digestible starch
disorganizationofstarchstructure. Thesampleswith (SDS) were obtained. This pattern is due to the
ANNandANN+SshowedasimilarX-raydiffraction fact that cooking of the fruit for 15 and 25 min
pattern, but a different crystallinity level (Fig. 4B). produced partial gelatinization of the starch granules,
Raw unripe banana flour and Raw+ANN had similar which could decreased the RS content (Aparicio-
crystallinitylevels, wherenochangewasobservedin Saguilan et al., 2005; Hernandez-Nava et al., 2011),
thepeakat2θ=17◦. Thistreatmentintherawsample as well as a production of short chains that can be
did not modify the crystalline structure of the starch, reorganized in some minutes, producing an increase
perhapsbecauseoftheothercomponentsoftheunripe in SDS content. The ANN and the ANN+S of
banana flour such as cellulose, hemicellulose, and the cooked unripe banana flour produced an increase
pectinswhichproduceaphysicalbarrierthatdecreases in RS content compared with their counterparts
the ANN effect on the starch granules. Jayakody without these treatments, with slight but significant
and Hoover (2008) found that a slight reduction in differences observed in the SDS content. ANN
potato starch crystallinity by ANN may be due to produced reorganization of the granular structure and
reflectionofcrystallinedisruptionorreorientation, as increased the granular stability that decreased the
reported by Vermeylen et al. (2006). According starch hydrolysis by the digestive enzymes (Tester et
to Gomes et al. (2004), annealed starches exhibit al., 1998). 25+ANN+S showed an increase in RS
a reduced intensity of the crystallinity peak. These contentcomparedwith25+ANN.Thestorageprocess
authorsreportedthattheincreaseinhelicalorderwas of gelatinized banana starch at low temperatures
produced by interactions between amylose (AM) and produced retrogradation with the increase in the RS
amylopectin(AMP)chains. Reducedinter-crystalline content(Bello-Pe´rezetal.,2005). Rawunripebanana
spacing may indicate that helical packing becomes starch without gelatinization before the Englyst?s
more compact and organized. The sample 15+ANN test showed an SDS content of 10.8% and RS of
showedanincreaseinthecrystallinitylevelcompared 85% (Carlos-Amaya et al., 2011). Gelatinization
with the sample with lower cooking time (data not of samples before the Englyst’s test decreased the
shown). This heat treatment creates disorganization RS content but increased the SDS level in the raw
in the physical barrier and produces a reorganization unripe banana flour (Table 1). In general cooking of
of the starch components; it is known that ANN samples at different times showed a lower RS level
could arise due to the interplay of the increase in but a higher SDS content. Samples with ANN and
crystalline order, the formation of new crystallites by ANN+S presented a similar pattern, showing that
the interactions among (AM-AM, AM-AMP, AMP- these treatments maintained the SDS fraction even
AMP) starch chains, and the increase in crystallite with the additional gelatinization treatment before
size and crystallite reorientation (Lan et al., 2008). the Englyst’s test. The analysis of unripe banana
At the longest cooking time (25 min), the effect is flour with different treatments and an additional
the inverse due to the decrease in the crystallinity heatingtreatmentcouldgivemoreinformationonthe
levelrecordedasisobservedinthepeakat2θ =17◦. digestibility properties and the possible applications
Cooking for 25 min produced starch gelatinization, in foods that need thermal treatment during their
but during annealing, it is not possible to reorganize preparation. The gelatinization treatment applied on
the starch components. The crystallinity level of the nativebananastarchbeforetheEnglyst’stestproduced
unripebananaflourwithdifferenttreatmentscouldbe areductioninRScontentbutaslightincreasedinthe
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SDSlevel(Carlos-Amayaetal.,2011). min of cooking showed lower values of breakdown
and setback, but the final viscosity upon cooling was
similar for raw, cooked for 5, and 15 min samples,
3.6 Pastingcharacteristics
indicating similar gel structure. Disorganization of
The pasting profiles of the unripe banana flour with thestarchcomponentsisresponsibleforthisbehavior.
thedifferenttreatmentsareshowninFig.5. Samples ANN and ANN+S produced an important change in
cookedforlongertimes(15and25min)showedlower the organization of starch components as evidenced
peakviscositythantherawsampleandsamplecooked in the pasting profile (Fig. 5B). A well-defined
for5min(Fig.4A),buttheformersamplespresented peak viscosity was not found in samples with both
the peak at higher temperatures. Cooking and treatments, a pattern that agrees with the microscopy
cooling produced arrangement of starch components study where aggregates of disorganized and melt-
that increased the thermal stability of those banana like starch granules were observed. However, the
floursaswasobservedinthethermalanalysisbyDSC. maximumpeakwasobservedduringtheholdingstep
Thispatternagreeswiththemicroscopyandamylose at 95 ◦C, indicating that the remnant structure is
leachingstudieswherenoappreciableeffectonstarch disorganized at higher temperature than the raw flour
and other components of the pulp was produced and that cooked for 15 min. This was also showed
with the shortest cooking time used. However, the in the thermal analysis. The samples 15+ANN and
breakdown was higher in the 5 min cooked sample 15+ANN+S did not show breakdown and setback,
than in the raw sample due to the conformation of indicatingasoftgelstructureuponcooling.According
starch granules which apparently presents a slight toLinebackandRasper(1988),severalfactorscontrol
disorganization during heating. Raw unripe banana theviscosityduringthepastingofstarch,includingthe
starch showed a similar pasting profile to raw unripe swellingofthegranulesandtheamountofsolubilized
banana flour (Espinosa-Sol´ıs et al., 2009; Carlos- starch;therefore,itcanbestatedthattheformationof
Amaya et al., 2011), but the viscosity values were atightlypackedarrayofswollen,granularaggregates
higher in the former due to the flour presenting other andtheleachingofmacromoleculescancontributeto
components such as fiber. Samples with 15 and 25 thedevelopmentofviscosityinstarchpaste.
Table1. Digestibilityvaluesofunripebananafloursamplescookedfordifferenttimesandtreated
underdifferentconditions.
Ungelatinizedsamples Gelatinizedsamples
Sample RDS(%) SDS(%) RS(%) RDS(%) SDS(%) RS(%)
R 2.5±0.1j 5.9±0.1g 66.5±0.1b 54.2±0.6c 10.9±0.9c 9.9±0.8b
5* 5.9±0.3f 7.5±0.4e 61.5±0.3d 52.1±0.4de 15.4±0.6a 7.5±0.5d
15* 42.8±0.2b 14.2±0.5bc 17.9±0.3gh 53.6±0.4d 14.2±0.4ba 7.2±0.4d
25* 49.7±0.7a 13.0±0.4bc 12.1±0.5i 55.8±0.3c 10.4±0.7c 8.8±0.5c
Raw+ANN 2.4±0.1j 3.7±0.4h 68.8±0.3a 52.8±0.7d 15.4±1.0a 6.8±0.9d
5+ANN 3.9±0.1h 6.8±0.1f 64.1±0.1c 51.3±0.7e 15.2±0.8a 8.5±0.7c
15+ANN 35.9±0.3d 15.2±0.6b 23.9±0.4e 58.0±0.5b 9.5±0.6dc 7.5±0.5d
25+ANN 42.4±0.5b 13.8±0.2cb 18.7±0.3g 59.4±0.6a 8.2±0.3e 7.4±0.4d
Raw+ANN+S 2.8±0.2i 3.8±0.5h 68.3±0.3a 50.8±0.2f 14.8±0.6a 9.4±0.6b
5+ANN+S 4.6±0.3g 6.0±0.3g 64.3±0.3c 52.1±0.5de 11.6±0.5c 11.3±0.5a
15+ANN+S 33.5±0.4e 18.2±0.1a 23.2±0.2ef 57.1±0.4b 9.0±0.4d 8.9±0.4cb
25+ANN+S 41.1±0.3c 9.9±0.2d 23.9±0.2e 58.9±0.7a 10.6±1.1c 5.5±0.7ed
Valuesinsamecolumnwithdifferentletteraredifferent(p<0.05).
R=Rawunripebananaflour.
RDS:Rapiddigestiblestarch,SDS:Slowdigestiblestarch,RS:Resistantstarch.
ANN=Annealing(65◦C,24h,70%watercontent);
ANN+S=AnnealingplusStorage(7days,4◦C).
*Timeoftheheatingtreatmentofgreenbananafruits(min)
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