Journal of Applied Botany and Food Quality 90, 126 - 131 (2017), DOI:10.5073/JABFQ.2017.090.015 1Laboratoire d’Etudes et Développement des Techniques d’Epuration et de Traitement des Eaux et Gestion Environnementale, Département de Chimie, Ecole Normale Supérieure de Kouba, Algiers, Algeria 2 Département de Biologie, Ecole Normale Supérieure de Kouba, Algiers, Algeria 3 Département de Physique, Ecole Normale Supérieure de laghouat, Algeria 4 Département des Sciences et Techniques, Faculté de Technologie, Université Amar Télidji - Laghouat, Algeria Starch digestion in pearl millet (Pennisetum glaucum (L.) R. Br.) flour from arid area of Algeria Mohamed Lemgharbi 1, 2, Rachid Souilah 1, 3, Badreddine Belhadi 1, 4, Ladjel Terbag 1, 3, Djaffar Djabali 1, Boubekeur Nadjemi 1 (Received August 28, 2016) * Corresponding author Summary To assess the nutritive value of minor cereals cultivated in arid ar- eas of Algeria, nine pearl millet landraces were sampled from two regions: Tidikelt and Hoggar. Some qualitative and quantitative cha- racters of the panicle and grain were measured, as well as in vitro starch digestion of the grain flour. Considerable variation was recor- ded in seed color, endosperm texture and nutritional value of starch and protein content. In vitro starch digestion displayed a first-order kinetic model. For all pearl millet landraces, starch was digested to a different extent; the hydrolysis index (HI) ranged from 22.29 % to 35.52 % and the expected glycemic index (eGI) ranged from 27.41 to 38.82. The results show that there is diversity in the physical and chemical properties of pearl millet accessions from the arid areas of Algeria: Tidikelt and Hoggar. This study confirms that pearl millet has an acceptable nutritional value with a low glycemic index suit- able for human health and nutrition. Keywords: Pearl millet, Starch digestion, First-order kinetics, Gly- cemic index, Nutrition. Introduction Pearl millet [Pennisetum glaucum (L.) R. Br.] is a small-seeded grass belonging to the Poaceae family and the Panicoideae subfamily. As it is a drought tolerant crop and has the ability to grow on low fertility soil and moisture (Fao and IcrIsat, 1996), it is mostly cultivated in arid and semi-arid areas of the Sahel in Africa and in Asia, where it is a major food source. Millet is the 6th largest cereal crop in terms of world agriculture production. Furthermore, millets have resistance to pests and diseases, a short growing season, and are productive under drought conditions, compared to major cereals (DevI et al., 2014). Millets are unique among the cereals because of their richness in calcium, dietary fiber, polyphenols and protein. Furthermore, as they do not contain gluten, they can be recommended for use by celiac patients (DevI et al., 2014). In addition to their nutritive value, several potential health benefits have been reported such as lowering the risk of cancer and cardiovascular disease, lowering blood pressure and risk of heart disease, lowering cholesterol and rate of fat absorption, and delaying gastric emptying by supplying gastrointestinal bulk (saleh et al., 2013). There are several plant characteristics that define grain quality, such as their structural and biochemical characteristics, digestibility, and bioavailability of nutrients. The structure of the grain kernels varies significantly because of environmental and genetic factors. Shape, size, proportion and nature of the endosperm, germ, and pericarp, the presence and absence of a subcoat, and color of the pericarp are all genetically determined (rooney and Murty, 1982). Grain digestibility also is important. Several works have been con- ducted to study the kinetics of starch digestion of different grains by alpha-amylase (ezeogu et al., 2005; FreI et al., 2003; gonI et al., 1997). The glycemic index (GI) is an in vitro measurement based on glycemic response to carbohydrate-containing foods, and allows ranking of food on the basis of the rate of digestion and absorption of carbohydrates that they contain (englyst et al., 1992; JenkIns et al., 1981). In vitro methods have also been used to classify foods based on their digestion characteristics similar to the in vivo situation, and to identify slow release of carbohydrate in foods (schweIzer et al., 1988; JenkIns et al., 1984). Food materials with GI values more than 70 %, between 56 and 69 % and lower than 55 % are classified as high, medium and low GI foods, respectively (BranD-MIller et al., 2003). In the Sahara of Algeria, the Tidikelt and Hoggar regions are cha- racterized by a typical desert climate; they are very hot and very dry. Moreover, rains have been rare during the last ten years. Aridity of the climate is extreme and the ambient temperature is very high in Tidikelt (in Salah), which is known to have temperatures ranging from 7.8 to 45.2 °C, a very low annual rainfall (16.9 mm), and ir- rigation is done with saline water. The Hoggar region is known to have temperatures ranging from 10 to 38 °C, with daily temperatures ranging over 23 °C, annual rainfall rate ranging from 7 to 160 mm, and irrigation is done with ground water. Despite these local hard climatic conditions, indigenous millet has maintained its original morphological diversity for centuries, and it has been able to accumu- late significant genetic diversity between populations. However, these environmental factors have affected the starch properties in different Sorghum genotypes (BelhaDI et al., 2012; BouDrIes et al., 2009; MastsukI et al., 2003). For example, pearl millet; (P. glaucum), is a cereal that also is called mil, mil à chandelle (French), and Dokhen (Arabic); the local appellation is “bechnna” and “inélé”, originally from West Africa, particularly, in the area north-east of the Senegal River. Millet was probably introduced during the eighth century into North Africa; its culture was intended to produce seed and fodder (tostaIn, 1998). Actually, pearl millet production in these margina- lized areas depends on traditional harvesting and processing. Most of the harvest is used as animal feed and rarely for human consumption. In the past, a wide range of traditional food products has been made from millet including kisra, porridge, and beverage. One of the objectives of our laboratory research is to study the nutri- tional and quality traits of Sorghum and pearl millet grains as well as the isolation of starch and protein fractions and their beneficial characteristics for food and non-food uses (souIlah et al., 2014; BelhaDI et al., 2012; haDBaouI et al., 2010; Mokrane et al., 2010; BouDrIes et al., 2009; Mokrane et al., 2009). In a previous work, the protein nutritional quality of seven Sorghum cultivars cultivated in the Sahara of Algeria was assessed (Mokrane et al., 2010). High percentages of protein, up to 16 % db, were found in these cultivars with a favorable amino acid composition. The measure of in vitro Starch digestion in pearl millet flours 127 pepsin digestibility shows that some cultivars exhibit high digestibi- lity, whereas, other cultivars are characterized by their low digesti- bility (Mokrane et al., 2010). The measurement of in vitro starch digestibility shows that the nine local Sorghum cultivars exhibit high digestibility of up to 90 % (souIlah et al., 2014). The aim of the present study is to evaluate the digestibility of starch in Algerian arid area pearl millet grain cultivars by investigating starch in vitro digestion in pearl millet grain flour, assessing the in vitro digestion kinetic data, and evaluating the effect of landrace dif- ferences on kinetic parameters. Materials and methods Materials Nine pearl millet [Pennisetum glaucum (L.) R. Br.] grains from local landraces were sampled from the arid Sahara areas of south Alge- ria: i.e., within Tidikelt and Hoggar. Landraces labeled as MLT.P, MLT.P.P, MLT.Saf, MDT.Smix, MLT.Ham, MDT.Sepl, MLH.Z, MLH.epc and MDH.Saf.T were harvested from different localities within Tidikelt and Hoggar; Djafou, Foggaret Ezzoua, El Malah, In Amghel, Tamanrasset and Abalessa. The samples were characterized by their kind of use (eg., cultivated millet, and domestic) and by dif- ferent harvest years (2008, 2010 and 2011). Tab. 1 lists pearl millet landraces from arid areas of Algeria. Millet grains were ground to flour in IKA Labotechik using an A10 sample mill. The flour was manually sieved using a 500 μm sieve. All reagents were analytical grade. Methods Pearl millet grain analysis Some qualitative and quantitative characters of pearl millet grains (seed envelop, seed color, seed form, thousand seed weight and bulk density) were categorized (IBpgr and IcrIsat, 1993). Grain color was assessed by the Royal Horticultural Society (RHS) color codes (IcrIsat, 1993). Endosperm texture was defined as the proportion of corneous relative to floury endosperm in the grain, which was deter- mined subjectively by viewing sectioned kernels using a stereomi- croscope, and comparing them to Sorghum standards (taylor and taylor, 2008). The kernels were classified as corneous, intermediate or floury (Icc, 2008). Moisture content was determined according to AACC methods 44-15A. The crude protein content was determined according to Micro kjeldahl method using a nitrogen conversion fac- tor of 5.83, based on an adaptation of the AACC 46-13A method (aacc, 2000). Total starch (TS) was determined by the enzymatic method of gonI et al. (1997). In vitro starch digestion In vitro starch digestion was determined according to the modified method of gonI et al. (1997). Around 600 mg of pearl millet flour was prepared in large tubes containing 25 ml of phosphate buffer (pH 6.9). To start starch hydrolysis, 5 ml of α-amylase (2 × 10-4 mg/ ml), type VI.B from porcine pancreas (A3172, Sigma-Aldrich) was added. The prepared mixture was incubated at 37 °C for 2 h with constant shaking. Aliquots of 0.2 ml were withdrawn at 5, 10, 15, 20, 30, 60, 90 and 120 min. α-Amylase was inactivated immediately by placing the tubes in a boiling water bath for 5 min. Then, 0.6 ml of a 0.4 M sodium-acetate buffer solution (pH 4.75), and 0.2 ml of an enzyme solution containing 0.833 μl of amyloglucosidase from Aspergillus niger (300 U/ml, Sigma, A-7095) were added. In order to hydrolyze digested starch into glucose, the sample was incubated at 60 °C for 45 min. Finally, the volume was adjusted to 1-5 ml with distilled water and glucose concentration in the digesta was mea- sured within the range (0.1-0.5 g/l) using an oxidase-peroxidase Kit (Biomaghreb, Tunisia). A concentration of free glucose (0.459 g/l) was used to correct the starch digestion values. Starch digestion was expressed as percentage on the amount of starch present at the start of the reaction. Modelling of starch digestograms First-order exponential kinetics were used to estimate starch hydro- lysis and glycemic indices in the food and feed studies (ezogu et al., 2005; FreI et al., 2003; gonI et al., 1997). Starch amylolysis data was fitted to a first-order equation (Eq. (1)): Ct = C∞ (1-exp [-kt]) (1) Where Ct corresponds to the percentage of starch hydrolysis at time t, C∞ is the equilibrium percentage of starch hydrolyzed after 120 min, k is the kinetic constant and t is the time (min). Glycemic and hydrolysis indices were determined from the area un- der the hydrolysis curve (AUCexp), which was obtained by integrating Eq. (1) between times t0 = 0 min and tf = 120 min getting Eq. (2) AUCexp = C∞ tf - C∞ / k (1-exp [-k tf ]) (2) The hydrolysis index (HI) expressed the ratio of the AUCexp of the sample from 0 to 120 min relative to the area under the hydrolysis curve of white bread (~ 7444 % min) (gonI et al., 1997). The ex- pected glycemic index eGI was calculated by the equation eGI=8.198 + 0.862 HI as described by granFelDt et al. (1992). Statistical analysis All the parameters of pearl millet panicle and grain quality were measured in three replicates, and expressed as mean±SD. Data anal- yses were performed using SigmaPlot V.10.0 (Systat software Inc, Chicago, Illinois, USA) for windows. Tab. 1: Pearl millet [P. glaucum (L.) R. Br.] landraces from the hyper area of Algeria: Tidikelt and Hoggar. No. Landraces codes Locality Region Status Harvest Date 01 MLT.P Djafou Tidikelt Cultivated millet 2008 02 MLT.P.P Foggarat Ezzoua Tidikelt Cultivated millet 2008 03 MLT.Saf Foggarat Ezzoua Tidikelt Cultivated millet 2008 04 MDT.Smix El malah Tidikelt Domestic* 2011 05 MLT.Ham Djafou Tidikelt Cultivated millet 2010 06 MDT.Sepl El Malah Tidikelt Domestic* 2011 07 MLH.Z In Amgheul Hoggar Cultivated millet 2008 08 MLH.epc Tamanrasset Hoggar Cultivated millet 2011 09 MDH.Saf.T Abalessa Hoggar Domestic* 2011 Domestic*: introduced from neighboring countries; Mali, Niger, Sénégal… (Local appellation is Sudan) 128 M. Lemgharbi, R. Souilah, B. Belhadi, L. Terbag, D. Djabali, B. Nadjemi Tab. 2: Qualitative and quantitative characters of pearl millet grains. N° Landraces codes SE SC SF 01 MLT.P Exposed(3) Grey (201) Obevate 02 MLT.P.P Intermediate(5) Grey (201) Oblanceolate 03 MLT.Saf Exposed (3) Yellow (8C) Oblanceolate 04 MDT.Smix Intermediate Grey brown (199) Hexagonal 05 MLT.Ham Intermediate (5) Brown (200) Oblanceolate 06 MDT.Sepl Enclosed (7) Ivory (158A) Obevate 07 MLH.Z Exposed (3) Deep grey (202B) Oblanceolate 08 MLH.epc Exposed(3) Deep grey (202B) Obevate 09 MDH.Saf.T Exposed (3) Yellow (8C) Globular SE: Seed envelop, SC: Seed color, SF:Seed form, TSW: Thousand Seed Weight, g, BD: Bulk density, g/L, H: Moisture, %, TS: Total starch, %, P: Protein, %. N° Landraces codes TSW (g) BD (g/L) H (%) TS (%) P (%) Endosperm texture (%) Corneous Intermediate Starchy 01 MLT.P 9.50 ±0.15 782.60 ± 3.15 09.61 57.02 ± 1.92 17.18 ± 0.58 95 5 0 02 MLT.P.P 9.10 ±0.10 780.40 ± 6.32 11.35 58.82 ± 5.56 15.18 ± 0.71 5 85 10 03 MLT.Saf 9.20 ± 0.70 782.50 ± 4.56 10.95 65.29 ± 7.19 11.41 ± 0.20 0 5 95 04 MDT.Smix 6.86 ± 0.22 778.00 ± 3.66 10.42 58.44 ± 7.97 14.15± 0.12 90 10 0 05 MLT.Ham 9.50 ± 0.08 782.60 ± 7.15 11.75 65.81 ± 2.12 16.89 ± 0.76 90 10 0 06 MDT.Sepl 6.20 ± 0.04 782.60 ± 3.55 10.27 65.87 ± 2.48 13.27 ± 1.83 80 20 0 07 MLH.Z 9.40 ±0.14 782.60 ± 2.81 13.11 69.07 ± 3.09 14.87 ± 0.50 100 0 0 08 MLH.epc 9.20 ±0.05 782.60 ± 5.16 11.55 63.06 ± 4.19 13.30± 0.89 0 5 95 09 MDH.Saf.T 9.80±0.12 782.60 ± 4.46 10.00 59.53 ± 9.69 14.24± 1.55 0 5 95 MLT.P : Pearl Millet Local fromTidikelt, MLT.P.P : Pearl Poilue (Hairy), MLT.Saf: Safra(Yellow), MDT.Smix: Domesticated from Soudan mix, MLT.Ham: Hamra(Red), MDT.Sepl: Soudan epi log (Tall Panicle), MLH.Z: Millet Local from Hoggar. Zarga (Blue), MLH.epc : Local Hoggar epi court (Short panicle), MDH.Saf.T : Domesticated Hoggar Safra (Yellow) from Tidikelt. Results and discussion Pearl millet grain analysis Some qualitative and quantitative characters of pearl millet grain were determined. As shown in Tab. 2, qualitative characters assessed were seed envelop (SE), seed color (SC) and seed form (SF). Seed en- velop was assessed as exposed, intermediate or enclosed; seed color was grey, yellow, grey brown, brown, ivory or deep grey, and seed form was obevate, oblanceolate, hexagonal or globular. In general, pearl millet landraces showed variation in phenotypic characters, in- dicating that Algeria has a high diversity in millet traits. The quantitative characters for all pearl millet landraces were thou- sand seed weight, bulk density, moisture, total starch and protein. Thousand seed weight varied from 6.20 ± 0.04 to 9.80 ± 0.12 g with a mean value of 8.75 g, which was in the range of the majority of mil- lets varieties from the data collected by DenDy (1995), which varied between 2.5 and 14.7 g. The bulk density varied from 778.00 ± 3.66 to 782.60 ± 7.15 g/l with a mean value of 781.83 g/l; these mean va- lues were lower than those reported for three pearl millets (850 g/l) looked at by JaIn (1997). Moisture content in pearl millet grains ranged from 09.61 % to 13.32 %. Visual examination of endosperm texture varied in percent- age of corneous (0 to 100 %), intermediate (0 to 85 %), and starchy (0 to 95 %) fractions (Tab. 2). This variation in endosperm texture indicated that the grains should be classified as corneous, floury, mixed and intermediate endosperm type as described by the Inter- natIonal assocIatIon For cereal scIence anD technology (2008). Total starch (TS) content of pearl millet flour ranged from 51.35 ± 5.35 to 69.07 ± 3.09 % db with a mean value of 61.43 % (Tab. 3). The grain chemical composition of pearl millet genotypes from the world collection at ICRISAT showed that starch compo- sition was between 62.8 % and 70.5 % with a mean value of 66.7 % (Fao, 1995). When compared to our results, the total starch content in the Algerian pearl millet samples was lower than the mean value. Moreover, the grain starch contents in the ten studied pearl millet landraces were lower than those in wheat (65 %) and higher than those observed in rye (60 %) and barley (55 %) (choct and hughes, 2000). However, our samples exhibited a lower total starch content than maize (75 %) and rice (80 %) (choct and hughes, 2000). The protein (P) content of pearl millet flour ranged from 09.62 ± 0.01 to 17.18 ± 0.58 % db with a mean value of 14.01 % (Tab. 3). The grain chemical composition of pearl millet genotypes from the world col- lection at ICRISAT showed that protein content was between 5.8 % and 20.9 % with a mean value of 10.6 % (Fao, 1995). The grain pro- tein contents in the ten pearl millet landraces studied were higher than the mean value. A large variation for grain qualitative and quantitative traits was ob- served in Algerian pearl millet landraces. Based on this variation, probably due to environmental conditions, high genotype diversity is found among landraces (rooney and MIller, 1982). In vitro kinetic starch digestion and Modelling Experimental data and computed digestibility curves were shown for all pearl millet flours in (Fig. 1). The kinetic curves show that the starches in pearl millet flours from Algeria landraces were hydro- Starch digestion in pearl millet flours 129 Tab. 3: Starch digestibility and expected glycemic index parameters of the first-order model for the pearl millet flours a. N° Landraces codes k(min-1) R2 SEE (%) C ∞(%) HI(%) eGI 01 MLT.P 0.24 0.97 4.40 22.83 35.52 38.82 02 MLT.P.P 0.13 0.99 0.86 19.42 29.30 33.45 03 MLT.Saf 0.23 0.99 1.44 15.54 24.14 29.01 04 MDT.Smix 0.22 0.99 0.78 19.54 30.31 34.32 05 MLT.Ham 0.21 0.96 4.50 21.25 32.90 36.55 06 MDT.Sepl 0.17 0.98 2.18 22.23 34.08 37.57 07 MLH.Z 0.29 0.91 9.23 14.24 22.29 27.41 08 MLH.epc 0.15 0.99 0.94 22.22 33.83 37.36 09 MDH.Saf.T 0.20 0.90 6.64 18.15 28.04 32.37 a Values are estimated from fit to experimental data, with R2> 0,9 and standard Error of estimate (SEE) < 6% for most landraces. Fig. 1: Digestibility curves obtained for pearl millet flours. lyzed by amylases. The extent of the reaction indicates that these flours have a low susceptibility to digestion. Predicted values for variables affecting starch amylolysis (C∞ and k), that were obtained from the first-order model, fit to the experimental data. Overall, computed digestibility curves provided a very good fit to all experimental data, with R2 > 0.9 and standard Error of estimate (SEE) < 6 % for most landraces. Predicted values (C∞, and k) were obtained from the first-model fit 130 M. Lemgharbi, R. Souilah, B. Belhadi, L. Terbag, D. Djabali, B. Nadjemi to the experimental data, reported in Tab. 3. The constant k ranged between 0.13 and 0.29 min-1; starch hydrolysis at infinite time C∞ varied from 14.24 to 26.38 %, and model-fit analysis of digestibility data was particularly well-suited to these studies. First-order model properties have been demonstrated in in vitro starch digestion of raw and processed food and feed (ezogu et al., 2005; FreI et al., 2003; gonI et al., 1997). The kinetic constant k of amylolysis has been proposed as a reliable index of the inherent sus- ceptibility of flour starches to amylase hydrolysis (FreI et al., 2003; gonI et al., 1997). Modeling of starch digestion kinetics is required to derive more quantitative information on digestibility properties. The hydrolysis index HI and expected glycemic index eGI are reported in Tab. 3. The hydrolysis index (HI) obtained by use of a first-order model fit to the experimental data ranged from the lowest in MLH.Z (22.29 %) to the highest MLT.P (35.52 %). This variation in starch digestibi- lity of pearl millet flours was due to grain quality differences in the sampled pearl millet landraces (rooney and pFlugFelDer, 1986). The expected glycemic index eGI varied from 27.41 to 38.82. Rela- tive to the glycemic index suggested by BranD-MIller et al. (2003), for Algerian pearl millet landraces (eGI < 55), the results of the GI for the eight local cultivars of Sorghum were high and ranged from 74.02 to 94.14 (souIlah et al., 2014). In the 2002 edition of the in- ternational table of Glycemic Index and Glycemic Load reported by Foster-powell et al. (2002), the glycemic index of boiled millet (Canada) was found to be 101, while that of millet flour porridge (Kenya) was 153 ± 14. ManI et al. (1993) also found that GI ranged from 55 ± 13 to 104 ± 13 after testing six commonly consumed Sor- ghum foods of India. The results indicate that starches from pearl millet samples in our work can be classified as having a low GI, al- though the GI values of Sorghum flours grown in Algeria are high with a GI value of up to 70 (souIlah et al., 2014). The HI and eGI values of pearl millet flours grown in Algeria were much lower, possibly due to differences in genetic source, growing conditions, and the employed methods used to determine HI and eGI. Conclusions The present study points out that differences in some morphologi- cal characteristics and biochemical components of the panicle and grains demonstrate diversity in the phenotype of pearl millet land- races in Algeria. Moreover, measure of in vitro starch digestibility shows that the nine local landraces examined exhibited low digesti- bility (< 40 %) and a low glycemic index (< 55). First-order kinetic analysis was used to model starch digestion of uncooked pearl millet flours. The digestibility properties of starches in pearl millet land- races showed high variability. This result suggests that there are good opportunities for utilization of pearl millet grain, grown in the Sahara of Algeria, for nutritional purposes and for potential health benefits especially for dealing with diabetes. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors Conflict of Interest All authors declare that they have no conflict of interest. References aMerIcan assocIatIon oF cereal cheMIsts, 2000: Approved methods of the AACC. 10th ed., Method 44-15A. The Association St.Paul. MN. BelhaDI, B., DJaBalI, D., souIlah, r., yousFI, M., naDJeMI, B., 2012: Three small-scale laboratory steeping and wet-milling procedures for isolation of starch from Sorghum grains cultivated in Sahara of Algeria. Food. Bioprod Process. 91, 225-232. DOI: 10.1016/j.fbp.2012.09.008 BouDrIes, n., Belhaneche, n., naDJeMI, B., Deroanne, c., MathlouthI, M., roger, B., sInDIc, M., 2009: Physicochemical and functional pro- perties of starches from sorghum cultivated in the sahara of Algeria. Carbohyd Polym. 78, 475-480. DOI: 10.1016/j.carbpol.2009.05.010 BranD-MIller, J., wolever, t.M.s., Foster-powell, k., colagIurI, s., 2003: The new glucose revolution. 2th ed., Marlowe & Company, New York. choct, M., hughes, B., 2000: The new season grain phenomenon: The role of endogenous glycanases in the nutritive value of cereal grains in broiler chickens. RIRDC publications No 00/143. DevI, p.B., vIJayaBharathI, r., sathyaBaMa, s., MalleshI, n.g., prI- yaDarIsInI, v.B., 2014: Health benefits of finger millet (Eleusine cora- cana L.) polyphenols and dietary fiber: A review. J. Food Sci. Techol. 51, 1021-1040. DOI: 10.1007/s13197-011-0584-9 DenDy, D.a.v., 1995: Sorghum and millets chemistry and technology. St. Paul, Minnesota, American Association of Cereal Chemists, Inc, USA. englyst, h.n., kIngMan, s.M., cuMMIngs, J.h., 1992: Classification and measurement of nutritionally important starch fractions. Eur. J. Clin. Nutrition. 46, 23-50. ezeocu, l.I., DuoDua, k.g., taylor, J.r.n., 2005: Effects of endosperm texture and cooking conditions on the in vitro starch digestibility of sorghum and maize flours. J. Cereal Sci. 42, 33-44. DOI:10.1016/j.jcs.2005.02.002 Fao, 1995: Sorghum and millets in human nutrition, collection FAO, Food and Nutrition Series, N° 27. Rome, Italy. Fao anD IcrIsat., 1996: The world sorghum and millet economies: Facts, trends and outlook. Foster-powell, k., holt, s.h.a., BranD-MIller, c.J., 2002: Internatio- nal table of glycemic index and glycemic load values. Am. J. Clin. Nutri- tion. 76, 5-56. FreI, M., sIDDhuraJu, p., Becker, k., 2003: Studies on the in vitro starch digestibility and glycemic index of six different indigenous rice cultivars from the Philippines. Food Chem. 83, 395-402. DOI : 10.1016/S0308-8146(03)00101-8 gonI, I., garcIa-alonsa, a., saura-calIxto, F., 1997: A starch hydrolysis procedure to estimate glycemic index. Nutrition Res. 17, 427-437. DOI: 10.1016/S0271-5317(97)00010-9 haDBaouI, z., DJerIDane, a., yousFI, M., saIDI, M., naDJeMI, B., 2010: Fatty acid, tocopherol composition and the antioxidant activity of the lipid extract from the sorghum grains growing in Algeria. Med. J. Nutri- tion Metab. 3, 215-220. DOI: 10.1007/s12349-010-0018-7 IBpgr anD IcrIsat., 1993: Descriptors for sorghum [Sorghum bicolor (L.) Moench] International Board for plant genetic Resources, Rome, Italy: International Crops Research Institute for the Semi-Arid Topics, Pa- tanchera, India. Icc. International Association for Cereal Science and Technology, 2008: Estimation of Sorghum Grain Endosperm Texture. ICC Standard 176, Vienna. JaIn, r.k., Bal, s., 1997: Properties of Pearl Millet. J. Agr. Eng. Res. 66, 85- 91. DOI: 10.1006/jaer.1996.0119. JenkIns, D.J.a., wolever, t.M.s., taylor, r.h, Barker, h.M., FIelD- en, h., BalDwIn, J.h., BowlIng, a.c., newMan, h.c., JenkIns, a.l., goFF, D.v., 1981: Glycemic index of foods: a physiological basis for car- bohydrate exchange. Am. J. Clin. Nutrition. 34, 362-366. JenkIns, D.J.a., wolever, t.M.s., thorne, M.J., JenkIns, a.l., wong, g.s., Josse, r.g., csIMa, a., 1984: The relationship between glycemic response, digestibility and factors influencing the dietary habits of dia- betics. Am. J. Clin. Nutrition. 40, 1175-1191. ManI, u.v., FIcn, B.M., DaMle, s.s., ManI, I., 1993: Glycaemic index of some commonly consumed foods in western India. Asia. Pac. J. Clin. Nutrition 2, 111-114. MatsukI, J., yasuI, t., kohyaMa, k., sasakI, t., 2003: Effects of environ- Starch digestion in pearl millet flours 131 mental temperature on structure and gelatinisation properties of wheat starch. Cereal Chem. 80, 476-480. DOI : 10.1094/CCHEM.2003.80.4.476 Mokrane, h., lagraIn, B., geBruers, k., courtIn, c.M., BrIJs, k., proost, p., Delcour, J.a., 2009: Characterization of Kafirins in Alge- rian Sorghum Cultivars. Cereal Chem. 86, 487-491. DOI: 10.1094/CCHEM-86-5-0487 Mokrane, h., aMoura, h., Belhaneche-BenseMra, n., courtIn, c.M., Delcour, J.a., naDJeMI, B., 2010: Assessment of Algerian sorghum protein quality [ Sorghum bicolor (L.) Moench] using amino acid ana- lysis and in vitro pepsin digestibility. Food Chem. 121, 719-723. DOI: 10.1016/j.foodchem.2010.01.020 rooney, l.w., MIller, F.r., 1982: Variation in the structure and kernel characteristics of sorghum. Proccedings of the international symposium on sorghum grain quality, 143-162, ICRISAT, Patancheru, India, rooney, l.w., Murty, D.s., 1982: Evaluation of sorghum food quality. Proc- cedings of the international symposium on sorghum grain quality, 571- 588. ICRISAT, Patancheru, India. rooney, l.w., pFlugFelDer, r.l., 1986: Factors affecting starch digesti- bility with special emphasis on sorghum and corn. J. Animal Sci. 63, 1607-1623. DOI:10.2527/jas1986.6351607x saleh, a.s.M., zhang, Q., chen, J., shen, Q., 2013: Millet grains: Nutri- tional quality, processing, and potential health benefits. Comp. Rev. Food Sci. Food Safety. 12, 281-295. DOI/10.1111/1541-4337.12012 schweIzer, t.F., reIMann, s., wursch, p., 1988: Definition and measure- ment of a starch digestion index and a study of factors determining starch digestion rates in foods. Food Sci. Technol. 21, 352-357. souIlah, r., DJaBalI, D., BelhaDI, B., Mokrane, h., BouDrIes, n., naD- JeMI, B., 2014: In vitro starch digestion in sorghum flour from Algerian cultivars. Food Sci. Nutrition. 2, 251-259. DOI: 10.1002/fsn3.104 tatlor, J.r.n., taylor, J., 2008: Five simple methods for the determina- tion of sorghum grain end-use quality. Intsormil Scientific Publications, 9-11. Address of the corresponding author: Mohamed Lemgharbi, Laboratoire de Biochimie, Département de Biologie, Ecole Normale Supérieure, BP 92 Kouba, Algiers, Algeria. E-mail address: Lemgharbim@yahoo.com or md.lemgharbi@hotmail.fr. © The Author(s) 2017. This is an Open Access article distributed under the terms of the Creative Commons Attribution Share-Alike License (http://creative- commons.org/licenses/by-sa/4.0/).