Plant Proteins - American Chemical Society

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16 Processing and Use of Dry, Edible, Bean Flours in Foods Mark A. Uebersax and Mary E. Zabik

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Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824

Navy, pinto and black beans (Phaseolus vulgaris) were dry roasted in a solid-to-solid heat exchanger, dehulled by air aspiration, pin-milled and air-classified to yield whole, hulls, high protein, and high starch flour fractions. Proximate analyses, color, enzyme neutral detergent fiber (ENDF), nitrogen solubility index, oligosaccharide content, SDS-PAGE, and in-vitro digestibility were determined and resulted in differences due to bean types, mill fractions, and processing variables. Samples of all fractions were analyzed by emission spectroscopy (ICP) for minerals. Phytate phosphorus was present in the greatest quantity in the protein fraction (0.861.06%). Protein digestibility of the cotyledonary fractions, high protein and high starch, was similar for both bean types. However, digestibility of the hull fraction was greater for navy bean than that obtained from pinto bean. All flour fractions retained stability during conventional storage protocols. Quality attributes of foods incorporating fractions were objectively and subjectively evaluated. Acceptable cookies, donuts, quick breads and leavened doughs were produced using high fiber or high protein fractions at moderate levels of substitution (20%) for wheat flour. Dry beans have been t r a d i t i o n a l l y prepared by s o a k i n g and c o o k i n g i n t h e home o r consumed as c o m m e r c i a l l y processed canned b e a n s . Whole beans r e q u i r e s o a k i n g and c o o k i n g t o e n s u r e u n i f o r m e x p a n s i o n o f t h e seed c o a t and h y d r a t i o n o f t h e c o t y l e d o n m a t r i x . Long c o o k i n g t i m e s r e q u i r e d t o a c h i e v e s a t i s f a c t o r y p a l a t a b i l i t y have impeded f u r t h e r u t i l i z a t i o n of d r y beans. The use o f d r y e d i b l e beans c o u l d be r e a d i l y expanded i f they were a v a i l a b l e i n the form o f a s h e l f stable f l o u r . Bean f l o u r s have been prepared by s o a k i n g and c o o k i n g beans i n 0097-6156/86/0312-0190$06.00/0 © 1986 American Chemical Society

Ory; Plant Proteins: Applications, Biological Effects, and Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1986.

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w a t e r and steam f o l l o w e d by temperature d e h y d r a t i o n over drum d r i e r s (Jj. Due t o t h e high c a r b o h y d r a t e and high p r o t e i n c o n t e n t s o f legume s e e d s , r e s e a r c h has been o r i e n t e d t o t h e p r o d u c t i o n o f h i g h s t a r c h and high p r o t e i n c o n c e n t r a t e s , u s i n g solvent extraction t e c h n i q u e s e i t h e r in p i l o t or commercial s c a l e . The p r o p e r t i e s and f u n c t i o n a l i t y of these c o n c e n t r a t e s have been e v a l u a t e d (2-5). Although t h i s wet p r o c e s s i n g method r e s u l t s in h i g h y i e l d s and h i g h percentage v a l u e s of p r o t e i n and s t a r c h in t h e c o n c e n t r a t e s , i t is energy i n t e n s i v e , generates l a r g e q u a n t i t i e s o f waste e f f l u e n t , and r e s u l t s in a d e c l i n e in n u t r i t i v e v a l u e due t o l e a c h i n g . M i l l i n g and f r a c t i o n a t i o n o f legumes t o produce f l o u r p r o d u c t s have r e c e i v e d i n c r e a s e d i n t e r e s t in r e c e n t y e a r s . M i l l e d products such as whole f l o u r and a i r - c l a s s i f i e d h i g h p r o t e i n and h i g h s t a r c h f r a c t i o n s from beans have demonstrated high n u t r i e n t r e t e n t i o n and have p r o v i d e d i n c r e a s e d v e r s a t i l i t y and improved u t i l i z a t i o n o f beans. A number of s t u d i e s on m i l l i n g of legume f l o u r s and i n c o r p o r a t i o n of f l o u r i n t o food p r o d u c t s have been r e p o r t e d ( 6 9). F i e l d peas have been s u c c e s s f u l l y m i l l e d i n t o whole f l o u r and a i r - c l a s s i f i e d i n t o high p r o t e i n and h i g h s t a r c h c o n c e n t r a t e s (6). Y i e l d and c o m p o s i t i o n a l d a t a of high p r o t e i n and high starch concentrates of various legume seeds obtained through airc l a s s i f i c a t i o n have been r e p o r t e d ( 7 - 9 ) . I t was n o t e d , however, t h a t legume seeds c o n t a i n a n t i n u t r i t i o n a l factors such as trypsin inhibitors and lectins which exert u n d e s i r a b l e e f f e c t s on n u t r i t i v e v a l u e i f they a r e not i n a c t i v a t e d (10-11). In a r e c e n t study (12) navy beans were d r y r o a s t e d in a particle-to-particle heat exchanger p r i o r t o m i l l i n g and airc l a s s i f i c a t i o n t o maximize t h e n u t r i t i v e p o t e n t i a l of t h e w h o l e , h u l l s , h i g h p r o t e i n , and h i g h s t a r c h f r a c t i o n s . The present research was conducted to evaluate selected p h y s i c o c h e m i c a l p r o p e r t i e s of t h e dry r o a s t e d and a i r - c l a s s i f i e d navy, p i n t o , and b l a c k bean f l o u r f r a c t i o n s . S t u d i e s were conducted t o determine t h e chemical c o m p o s i t i o n and t o c h a r a c t e r i z e t h e f u n c t i o n a l p r o p e r t i e s o f d r y - r o a s t e d bean f l o u r f r a c t i o n s and t o e v a l u a t e t h e s u i t a b i l i t y of t h e f l o u r s f o r use in foods s y s t e m s . Pry Bean Processing Dry beans (Phaseolus vulgaris), r e p r e s e n t e d by t h e commercial classes of navy, p i n t o and b l a c k were used t o produce flour f r a c t i o n s at t h e Food P r o t e i n Research and Development C e n t e r , Texas A & M University. Beans were d r y - r o a s t e d under s e l e c t e d p r o c e s s c o n d i t i o n s in a gas f i r e d s o l i d - t o - s o l i d heat exchanger, d e h u l l e d by a i r a s p i r a t i o n , p i n - m i l l e d and a i r - c l a s s i f i e d t o o b t a i n f o u r f l o u r fractions. These f r a c t i o n s i n c l u d e d w h o l e , h u l l s , high p r o t e i n , and high s t a r c h f l o u r s . Roasting and Dehulling The heat t r a n s f e r medium of t h e exchanger c o n s i s t e d of 1.6 mm (1/16") d i a m e t e r , t y p e A, 90% aluminum o x i d e c e r a m i c beads (Coors Ceramic C o . , Golden C i t y , CO) w i t h a s p e c i f i c g r a v i t y of 3.6 g/crrr. S e l e c t e d r o a s t i n g c o n d i t i o n s were m a i n t a i n e d by c o n t r o l o f bead temperature and r e s i d e n t t i m e . The beads were heated t o 240°C and were m a i n t a i n e d in the chamber w i t h t h e raw beans f o r 100 seconds in a 1:5 r a t i o of beans t o beads. These processing c o n d i t i o n s r e s u l t e d in an e x i t temperature of t h e beans of 113°C. Roasted beans were c r a c k e d through a c o r r u g a t e d r o l l e r m i l l ( F e r r e l l

Ory; Plant Proteins: Applications, Biological Effects, and Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1986.

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R o s s ; Oklahoma C i t y , OK) i n t o 6 t o 8 p i e c e s . The h u l l s , or seed c o a t s , were removed u s i n g a z i g - z a g a s p i r a t o r ( K i c e Metal P r o d u c t s ; W i c h i t a , KS). A h u l l f l o u r f r a c t i o n was produced by g r i n d i n g t h e hull pieces through a swinging blade Model D6 F i t z m i l l (W.J. Fitzpatrick Co., Chicago, IL) using the impact surfaces for p u l v e r i z a t i o n through a O.69 mm (1/37") round h o l e s c r e e n . Grinding and Air C l a s s i f i c a t i o n A f t e r h u l l r e m o v a l , the c r a c k e d c o t y l e d o n s were m i l l e d and a i r c l a s s i f i e d at A l p i n e American C o r p o r a t i o n p i l o t f a c i l i t i e s ; N a t i c k , MA. The c r a c k e d c o t y l e d o n s were f i n e l y ground in a Model 250 CW Stud Impact M i l l at a speed o f 11,789 rpm and a door speed o f 5,647 rpm. The r e s u l t i n g f l o u r s were a i r - c l a s s i f i e d in a Model 410 MPVI A i r C l a s s i f i e r at a r o t o r speed o f 2,200 rpm and a brake r i n g s e t t i n g o f 3 , u s i n g a 7.62 cm (3 i n c h ) screw f e e d e r o p e r a t i n g at 25 rpm. I n i t i a l l y , two f l o u r f r a c t i o n s were o b t a i n e d : an i n t e r m e d i a t e s t a r c h f r a c t i o n ( c o a r s e I) and an i n t e r m e d i a t e p r o t e i n f r a c t i o n (fines I). The i n t e r m e d i a t e p r o t e i n f r a c t i o n was r e c l a s s i f i e d under the f o l l o w i n g c o n d i t i o n s : r o t o r speed o f 2,200 rpm; brake r i n g s e t t i n g of 0; 7.62 (3 i n c h ) screw f e e d e r o p e r a t i n g a t 25 rpm. As a result of t h i s second a i r c l a s s i f i c a t i o n s t e p , a high starch f r a c t i o n ( c o a r s e II) and a h i g h p r o t e i n f r a c t i o n ( f i n e s II) were o b t a i n e d . The f i n a l m a t e r i a l s produced as a r e s u l t o f t h e p r o c e s s e s d e s c r i b e d i n c l u d e d t h e h u l l f l o u r f r a c t i o n and t h r e e a i r - c l a s s i f i e d fractions: intermediate starch (starch I ) , high starch (starch II), and h i g h p r o t e i n ( p r o t e i n I I ) . A f l o w diagram showing t h e f l o u r p r o c e s s i n g scheme and t h e f r a c t i o n s produced appears in F i g u r e 1. The percentage y i e l d o f each f r a c t i o n o f each bean t y p e is shown in figure 2. Physico-Chemical Characteristics Composition Chemical a n a l y s e s of m o i s t u r e , f a t , d i e t a r y f i b e r , ash and p r o t e i n were conducted on a l l f l o u r f r a c t i o n s . Chemical measurements a r e important to c h a r a c t e r i z e the s p e c i f i c n u t r i t i o n a l p r o p e r t i e s of each f r a c t i o n and t o a i d in d e t e r m i n i n g each f r a c t i o n ' s s u i t a b i l i t y f o r use in s e l e c t e d p r o d u c t s . F i g u r e 3 show t h e d a t a from t h e average of e i g h t t r e a t m e n t s on chemical c o m p o s i t i o n o f r o a s t e d navy bean f l o u r f r a c t i o n s . M o i s t u r e c o n t e n t s of t h e s e f r a c t i o n s ranged from 6.0 t o 8.9%. L i m i t e d f a t c o n t e n t was found in a l l f r t i o n s w i t h the high protein fraction containing the greatest fat level (2.3%). H i g h e s t ash c o n t e n t was found in h u l l f l o u r w i t h s l i g h t l y lower ash v a l u e s in t h e remaining t h r e e f l o u r s . As e x p e c t e d , f i b e r c o n t e n t of h u l l f l o u r was very h i g h (40.5%) as was p r o t e i n c o n t e n t (42.5%) of h i g h p r o t e i n f r a c t i o n . A Hunter C o l o r and C o l o r D i f f e r e n c e Meter was used t o e v a l u a t e flour color. The e f f e c t of r o a s t i n g c o n d i t i o n on Hunter L v a l u e s o f f l o u r s i n d i c a t e d t h a t l i g h t n e s s v a l u e s (L) decreased w i t h i n c r e a s e d roasting temperature and t i m e w i t h a l l navy bean cotyledonary f r a c t i o n s possessing a c l e a r l i g h t appearance. I d e n t i f i c a t i o n and q u a n t i t a t i v e a n a l y s i s o f o l i g o s a c c h a r i d e s by h i g h performance l i q u i d chromatography (HPLC) was done t o determine p o t e n t i a l problems w i t h f l a t u l e n c e . S t a c h y o s e , which was h i g h e s t in h i g h p r o t e i n f l o u r , was the major o l i g o s a c c h a r i d e , f o l l o w e d by s u c r o s e and g l u c o s e , w i t h a t r a c e amount o f r a f f i n o s e . Hull f l o u r had t h e l o w e s t t o t a l sugar l e v e l among f r a c t i o n s .

Ory; Plant Proteins: Applications, Biological Effects, and Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1986.

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193

Processing and Use of Bean Flours

UEBERSAX AND ZABIK

W H O L E

B E A N S

IROASTINGI IDEHULLINGI • r fA S P I R A T I O N! • HULLS

COTYLEDONS

GRINDING

IPIN MILLING I

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HULL

IAIR CLASSIFICATION!

FLOUR

STARCH I

PROTEIN I

.

I

.

jAIR CLASSIFICATION STARCH II

1

ΤΓ

High Starch Flour

PROTEIN II High Protein Flour

Figure 1. Flow diagram of f l o u r processing scheme. with permission from reference 33.)

NAVY

PINTO

BLACK S-1

H - HULL

S - 1 - STARCH I

(Reproduced

S-2

S-2 - STARCH II

S-1

Ρ - PROTEIN

Figure 2. Percentage y i e l d of f l o u r fractions obtained from navy, p i n t o , and black beans. (Reproduced with permission from reference 33.)

Ory; Plant Proteins: Applications, Biological Effects, and Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1986.

PLANT PROTEINS

194

NAVY BEAN HULL FLOUR

WHOLE NAVY BEAN FLOUR

40 38 16

f

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14 ,ο 12 10 8 6 4 2 "

MOISTUR

FRESH BASIS

FAT DIETARY ASH PROTEIN FIBER

— D R Y WEIGHT B A S I S — *

NAVY BEAN STARCH FRACTION

MOISTURE

FRESH BASIS

FAT DIETARY ASM PROTEIN FIBER

— D R Y WEIGHT B A S I S —

MOISTURE

FRESH BASIS

FAT

DIETARY ASM PROTEIN FIBER

— D R Y WEIGHT BASIS — *

NAVY BEAN HIGH PROTEIN FRACTION

MOISTURE

FRESH BASIS

FAT

DIETARY ASM PROTEIN FIBER

- — D R Y WEIGHT B A S I S — -

F i g u r e 3. P r o x i m a t e c o m p o s i t i o n o f d r y r o a s t e d , a i r - c l a s s i f e d navy bean f l o u r f r a c t i o n s .

Ory; Plant Proteins: Applications, Biological Effects, and Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1986.

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N i t r o g e n S o l u b i l i t y Index (NSI) a n a l y s e s were conducted on navy bean a i r - c l a s s i f i e d p r o t e i n f r a c t i o n s t o a s s e s s t h e i n f l u e n c e o f p r o c e s s i n g parameters on p r o t e i n f u n c t i o n a l i t y . N i t r o g e n S o l u b i l i t y Index Method 46-23 (_13) was m o d i f i e d by p l a c i n g a 400 mL beaker c o n t a i n i n g t h e w a t e r - f l o u r m i x t u r e on a mechanical s t i r r e r and s t i r r i n g at 120 rpm f o r 120 min a t 30°C. Nitrogen solubility i n d i c e s o f p r o t e i n f l o u r s a r e shown in F i g u r e 4. R e s u l t s i n d i c a t e d that increases in roasting temperature and t i m e significantly reduced t h e NSI v a l u e s . Dough M i x i n g C h a r a c t e r i s t i c s Three bean f l o u r f r a c t i o n s were s u b s t i t u t e d f o r 10% bread f l o u r t o study Theological p r o p e r t i e s o f t h e dough and t h e r e s u l t s a r e presented in Table 1. Farinograms showed changes in a r r i v a l t i m e and a slight but c o n s i s t e n t decrease in peak time f o r a l l fractions. Water a b s o r p t i o n and dough s t a b i l i t y were greatly affected. S u b s t i t u t i n g 10% bean h u l l f l o u r had t h e g r e a t e s t e f f e c t in i n c r e a s i n g water a b s o r p t i o n . The 60.8% water a b s o r p t i o n v a l u e f o r wheat f l o u r standard i n c r e a s e d t o 74.4% w h i l e t h e m i x i n g s t a b i l i t y changed from 6.0 min t o 2.3 m i n . Whole bean f l o u r had t h e l e a s t e f f e c t w i t h a water a b s o r p t i o n o f 61.3% and a dough s t a b i l i t y o f 3.5 m i n . The e f f e c t o f s u b s t i t u t i n g t h e h i g h p r o t e i n f r a c t i o n was s l i g h t l y l e s s d e t r i m e n t a l than t h a t which o c c u r r e d w i t h navy bean h u l l s . The i n c r e a s e in water a b s o r p t i o n and r e d u c t i o n in dough s t a b i l i t y due t o t h e s u b s t i t u t i o n o f bean f l o u r g e n e r a l l y agreed w i t h d a t a r e p o r t e d by D ' A p p o l o n i a (14) and Sathe et a l . ( 1 5 ) . P h y t i c A c i d and M i n e r a l Content A n a l y s e s were performed t o determine t h e q u a n t i t y and p a r t i t i o n i n g p a t t e r n o f e i g h t m i n e r a l s and p h y t i c a c i d among f i v e f l o u r f r a c t i o n s d e r i v e d from navy, p i n t o , and b l a c k b e a n s . A f t e r o b t a i n i n g d a t a on m i n e r a l c o n t e n t , p h y t i c a c i d c o n t e n t , and proximate c o m p o s i t i o n o f each f l o u r f r a c t i o n o f t h e t h r e e bean t y p e s , t h e study also attempted to correlate the individual microconstituents with macroconstituents. An inductively coupled plasma emission s p e c t r o m e t e r was employed t o measure t h e Z n , F e , C a , C u , N a , K, Mg, and Ρ content o f each sample. The e x t r a c t i o n and p r e c i p i t a t i o n o f p h y t i c a c i d was accomplished a c c o r d i n g t o t h e method o f Wheeler and F e r r e l ( 1 6 ) . Makower's (17) method was then used t o c o n v e r t f e r r i c phytate t o f e r r i c hydroxide. The A0AC (18) method f o r measuring ferric iron using ortho-phenanthroline was f o l l o w e d . Phytate phosphorus content was c a l c u l a t e d from iron c o n c e n t r a t i o n by assuming a 4:6 atomic r a t i o o f i r o n t o phosphorus ( 1 6 ) . Phytic acid c o n t e n t was e s t i m a t e d on t h e b a s i s t h a t 28.20% o f t h e weight o f p h y t i c a c i d is c o n t r i b u t e d b y . O v e r a l l , t h e l a r g e number o f s i g n i f i c a n t d i f f e r e n c e s among t h e f r a c t i o n s o f a l l t h r e e bean t y p e s , r e v e a l s t h a t t h e v a r i o u s m i n e r a l s s t u d i e d were not e q u a l l y d i s t r i b u t e d among t h e f r a c t i o n s , except f o r sodium, but rather that p a r t i t i o n i n g o c c u r r e d . Consistent with t h e ash v a l u e s o b t a i n e d , t h e p r o t e i n f l o u r f r a c t i o n s o f t h e t h r e e bean t y p e s c o n t a i n e d l a r g e r amounts o f F e , Mg, Ρ, Z, and Κ whereas t h e s t a r c h II f r a c t i o n s c o n t a i n e d s m a l l e r amounts o f t h e s e m i n e r a l s and Ca and Cu t h a n t h e o t h e r f l o u r f r a c t i o n s . Phytic acid content ranged from 8.7-30.2 mg/g f o r navy f l o u r s , from 4.3-23.7 mg/g f o r pinto f l o u r s . T o t a l phosphorus c o n t e n t c o r r e l a t e d w e l l w i t h both p h y t i c a c i d c o n t e n t and p r o t e i n c o n t e n t . P h y t i c a c i d c o n t e n t was

Ory; Plant Proteins: Applications, Biological Effects, and Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1986.

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F i g u r e 4 . Mean n i t r o g e n s o l u b i l i t y index (%) f o r p r o t e i n f l o u r dry r o a s t e d under v a r i o u s p r o c e s s i n g c o n d i t i o n s : bean/bean r a t i o n (1/10, 1/15); r e s i d e n c e t i m e ( 1 , 2 m i n ) ; and bead t e m p e r a t u r e (240, 270 C) . Means w i t h s i m i l a r l e t t e r s are not s i g n i c a n t l y d i f f e r e n t , P