Hard Endosperm Research Articles

Comparison of Indian corn with The US and South American commodity corn for wet milling starch yields

Higher starch extractability is critical for improving the profitability of a corn wet milling process. The starch extractability of Indian corn was compared to the corn grown in the USA, Brazil, and Argentina. Two corn crops (rainy and winter season) are produced every year in India. The endosperm hardness of Indian samples was similar to South American corn and higher than the US corn. Extractable starch yields of Indian corn samples were 2–3 % lower than the average starch yield of US commodity corn, however, was comparable with Brazilian, and Argentinian. No significant difference in starch yields between two crop years was observed. However, starch yield from the rainy (Kharif) season was lower compared to the winter (Rabi) season. Like South American corn, Indian corn contains a hard endosperm and resulted in a lower starch yield than the soft endosperm US corn. This information is useful for corn wet milling plants that buy commodity corn from various geographic locations around the world.

Drying stress analysis and cracking prediction of the component of maize based on viscoelastic stress-strain model

To study the drying stress and predict cracking of the components of the maize kernel during drying, the viscoelastic stress-strain model of the maize kernel was developed considering the differences in viscoelastic properties of the components. The results showed that at the preheating and main drying stages, the stress was mainly caused by the uneven distribution of the moisture content and gradually increased with drying. At the cooling stage, the stress significantly increased in a short time due to the decrease in temperature. The stress of the hard endosperm was higher, the pericarp had the highest stress value, and the stress of the soft endosperm and germ was low. The crack volume percentage of the germ and pericarp was zero, which was consistent with the fact that there was no crack in the pericarp and germ, the cracks were mainly in the endosperm. The crack volume percentage of the endosperm gradually increased as drying progressed and significantly increased during the cooling stage, which was similar to the increasing trend in the crack degree of the endosperm at different drying stages. The viscoelastic stress-strain model combined with the von Mises stress criterion could be used to predict the stress crack formation of components at different drying stages.

Effect of glass transition on the formation of drying cracks in the component parts of maize kernels

Glass transition can cause the formation of drying cracks in different component of maize (Zea mays) at different drying stages, but the influence of the mechanism is unknown. This work aimed to study the effect of glass transition on crack formation in different components. It was found that the differences in moisture content, temperature distribution, and glass transition temperature of the components can cause different glass transition processes in the components at different drying stages with 55 °C hot air. The temperatures of the pericarp and germ were found to be higher and lower, respectively, than corresponding the glass transition temperature, so remained in a single state, resulting in the absence of cracks. Cracks generated in the hard endosperm and then extended to soft endosperm, which was consistent with the glass transition of the endosperm. At the preheating stage, the endosperm had no cracks. After the main drying stage, the stress crack index (SCI) of hard and soft endosperm were 160.0 and 65.3, respectively. After the cooling stage, the SCI of the hard and soft endosperm increased to 402.3 and 163.3, respectively. Cracks were mainly formed during the main drying and cooling stages, and more cracks formed in the cooling stage. The cracking in the components at different drying stages could be well explained by glass transition.

Mechanical properties of corn: Correlation with endosperm hardness

AbstractThe purpose of this study was to explore the effects of different factors on the compressive mechanical properties of corn kernels. Explore the relationship between endosperm hardness and compressive mechanical properties of corn kernels by polynomial regression analysis. The results showed that the variety and kernel orientation had a significant effect on the compressive mechanical properties of corn kernels. Flint corn had a stronger ability to resist damage than floury corn. As the loading rate increased from 5 to 25 mm/min, the rupture force and rupture energy of corn kernels changed accordingly. The hardness of horny endosperm was significantly higher than that of floury endosperm. The dense starch‐protein network structure of horny endosperm leads to higher hardness. According to the fitting results, the compressive mechanical properties of corn kernels could be predicted using the hardness of the horny endosperm within a certain range.Practical applicationsAs a widely planted food crop in the world, corn is not only an important food crop, but also a high‐quality feed for livestock and poultry. The compressive mechanical properties (elastic modulus, compressive failure force, failure energy, etc.) of corn kernels were explored, and the relationship between endosperm hardness and its mechanical properties was analyzed. It can provide technical parameters for mechanical processing equipment, reduce the loss of corn grain in the processing process, and improve its economic value.

PSIII-5 Endosperm Hardness in Corn Affects the Digestibility of Energy and Fiber, and Increased Drying Temperature Reduces Amino Acid Digestibility

Abstract Two experiments were conducted to test the hypothesis that corn source and drying temperature influence the ileal digestibility of starch and amino acids (AA), as well as apparent total tract digestibility (ATTD) of gross energy (GE) and total dietary fiber (TDF) in diets for growing pigs. Two corn sources (i.e., soft or hard endosperm) were procured, and sources were divided into two drying batches (i.e., 35 or 120 oC). Therefore, four corn sources were used. In experiment 1, ten pigs (67.00 ± 2.98 kg) with a T-cannula installed in the distal ileum were allotted to a replicated 5 × 5 Latin square design with five diets and five periods giving ten replicates per diet. A nitrogen-free diet and four diets containing each source of corn as the only AA source were formulated. Data were analyzed in a 2 × 2 factorial arrangement of treatments using the MIXED procedure of SAS. The model included corn source, drying temperature, and the interaction between corn source and drying temperature. Results indicated that neither source nor drying temperature influenced the apparent ileal digestibility of starch in corn (Table 1), but the standardized ileal digestibility of most AA was less (P < 0.05) in corn dried at 120 oC compared with corn dried at 35 oC. In experiment 2, 40 pigs (20.82 ± 1.74 kg) were housed in metabolism crates and allotted to four diets with ten replicate pigs per diet. The four corn-based diets used in experiment 1 were also used in experiment 2. Feces and urine were collected using the marker-to-marker approach with 5-day adaptation and 4-day collection periods. Data were analyzed as explained for experiment 1. Results indicated that diets containing hard endosperm corn had greater (P < 0.05) ATTD of TDF compared with diets containing soft endosperm corn. The ATTD of GE and the concentration of metabolizable energy (ME) in hard endosperm corn were also greater (P < 0.05) compared with soft endosperm corn. Diets containing corn dried at 120 oC had greater (P < 0.05) ATTD of TDF compared with diets containing corn dried at 35 oC, but drying temperature did not influence ATTD of GE or ME. In conclusion, endosperm hardness did not influence the digestibility of AA and starch; however, drying corn at 120 oC resulted in reduced digestibility of AA. Hard endosperm corn had greater ATTD of GE and TDF, but drying temperature did not influence energy digestibility.

Elucidation of zein isoforms associated with high protein quality traits for targeted improvement in maize‐based nutrition

AbstractBackground and ObjectivesZein proteins of maize endosperm are nutritionally poor, but important for vitreous kernel texture. The Opaque‐2 mutation enhances the protein quality but downregulates zein expression, distorting the kernel texture. Quality protein maize (QPM) is nutritionally improved, hard endosperm maize developed by introgression of endosperm modifiers under an opaque‐2 background. The present study aims to analyze the variability in zein expression patterns in normal, opaque‐2, and QPM lines through sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and two‐dimensional gel electrophoresis analyses.FindingsResults revealed that the total number of zein isoforms is almost similar in opaque‐2, normal, and QPM lines. Overall, in this study, it is concluded that the opaque‐2 mutation specifically affects the expression of high‐molecular‐weight zeins, which are being counterbalanced by the expression of low‐molecular‐weight zein isoforms and nonzein proteins.ConclusionGenomic data retrieval studies revealed the possible presence of multiple 27 kDa isoforms with varied isoelectric points (pI), which is a subject for further investigation. The differential expression of 15 kDa zein in QPM emerged as a novel player in endosperm modification.Significance and NoveltyThe present study provides insight into the diversified expression of zeins in different maize types. The variable isoform expression has the potential to generate stable QPM lines by targeting effective isoforms, ensuring endosperm modification without hampering the nutritional quality.

Corn kernel hardness and drying temperature affect particle size post-hammer-milling and pellet quality in broiler and swine diets

The particle size (PS) of ground corn affects the live performance, nutrient digestibility, energy utilization, and gut health of poultry and swine. Endosperm hardness influences kernel breakability. The interactive effects of corn moisture content at harvest and drying temperature (DT) can also affect starch-protein matrix structure, breakage susceptibility, and pellet durability. The objective of this study was to evaluate the effects of drying temperature (35 or 120 °C) in two yellow-dent corn hybrids with different kernel hardness (average and hard) on the geometric mean diameter (dgw) and standard deviation by weight (Sgw) when hammermilled, and pellet quality. Four different settings combinations of tip speeds (4213, 3862, 3335, and 2458 m/min) and screen of 8/64", 3.18 mm (8 −8); 20/64", 7.94 mm (20 −20); 24/64", 9.53 mm (24 −24); and 24/64", 9.53 mm (24 −24) respectively were used to target four dgw (400, 700, 925, and 1250 µm). After grinding, the 400 and 700 µm corn were included in broiler and sow diets to assess the impact of these treatments on the pellet durability index (PDI). Grinding and pelleting data were analyzed using a 2 × 2 factorial arrangement of two corn varieties (CV) and two DT in a randomized complete block design with blocks by grinding or pelleting event. The average hardness CV generally had the lowest dgw. The hard CV had the biggest dgw when kernels were dried at 35 °C, and the tip speed setting was 3335 m/min. Drying at 120 °C increased dgw for the average hardness CV when the target PS were 700, 925, and 1250 µm, but caused no increase in dgw at the lowest target PS. In contrast, the dgw of hard CV was not affected by DT when ground to target 700 and 1250 µm and increased at 400 µm with the high DT. The average hardness CV had higher Sgw, especially when dried at 35 °C. Higher particle uniformity (lower Sgw) was observed with hard CV. Diets containing the hard CV presented better PDI than diets with the average CV. Better broiler feed PDI was observed with corn dried at 120 °C than at 35 °C. However, this effect was the opposite when grinding at a lower PS target for sow gestation diets. The PS distribution and damaged starch of corn affected PDI. Higher corn DT affected dgw and Sgw differently depending on CV and improved PDI in broiler diets, while 35 °C DT improved PDI in sow diets.

EXPANSIÓN DE LOS CONOCIMIENTOS BÁSICOS DE LA HERENCIA DE CARACTERES QUE POSIBILITEN DESARROLLAR NUEVAS TÉCNICAS DE MEJORAMIENTO EN MAÍZ

In order to increase the efficiency of maize hybrid seed production it is necessary to achieve a high grain yield to reduce production costs. This goal requires an expansion of the basic knowledge of the inheritance of characters in order to develop new breeding techniques to improve experimental materials with hard endosperm (flint). The balanced lethal system allows to study the relative contribution of different chromosome segments to hybrid vigour due to the heterozygosity of certain chromosome segments while the rest of the genome becomes homocygotic through continuous selfing. In this way, these segments can be transferred to inbred lines in order to increase grain yield or tassel size (to increase pollen production). The goal of this study was to transfer a heterotic segment by using a balanced lethal system regulated line (BLS14), through crosses and backcrosses, to S5 flint lines derived from two commercial hybrids, ACA 2000 and Cóndor with closed pedigree, with the objective of increase grain yield or tassel size for pollen production. The analysis of variance (ANOVA) and principal components analysis (PCA) showed a significant improvement in grain yield and tassel size in the S5 flint lines of both commercial hybrids, carrying the heterotic segment of the BLS14 line. Key words: maize, heterotic segments, grain yield, inbred lines

Characterization and Comparison of Wet Milling Fractions of Export Commodity Corn Originating from Different International Geographical Locations

AbstractSoft endosperm corn has evident characteristics suitable for wet milling but is susceptible to breakage and fracture during transportation. In this study the millability of commodity corn samples with different endosperm hardness originating from different international locations is compared, and its economic impact on corn importers for wet milling is discussed. The broken corn and foreign material (BCFM) for the soft endosperm US commodity corn ranges from 1.13% to 5.57% which is higher than other commodity corn from other international locations exported to the same country. US corn exported to different international markets shows higher starch yield in a range of 5–8% compared to the corn from different geographical locations exported to the same market. The excess starch from US corn directly translates to an additional revenue of 8.13–13 million USD per year for a 2540 MT day−1 wet mill plant. Therefore, it can be concluded that the soft endosperm US commodity corn, despite higher breakage, has superior millability and gives higher starch yields compared to the hard endosperm corn from other international locations which has comparatively lower BCFM. There are technologies that can be used to process broken corn separately after the initial cleaning process.

Effects of corn hardness and drying temperature on digestibility of energy and nutrients in diets fed to growing pigs.

Two experiments were conducted to test the hypothesis that corn kernel hardness and drying temperature influence the ileal digestibility of starch and amino acids (AA), as well as apparent total tract digestibility (ATTD) of gross energy (GE) and total dietary fiber (TDF) in diets for growing pigs. Two corn varieties with average or hard endosperm were grown and harvested under similar conditions, and after harvest each variety was divided into 2 batches that were dried at 35 oC and 120 oC, respectively. Therefore, four batches of corn were used. In experiment 1, ten pigs (67.00 ± 2.98kg) with a T-cannula installed in the distal ileum were allotted to a replicated 5 × 5 Latin square design with five diets and five periods giving ten replicates per diet. A nitrogen-free diet and four diets containing each source of corn as the only AA source were formulated. Results indicated that neither variety of corn nor drying temperature influenced apparent ileal digestibility of starch in the grain. The standardized ileal digestibility of most AA was less (P < 0.05) in corn dried at 120 oC compared with corn dried at 35 oC resulting in concentrations of most standardized ileal digestible AA being less (P < 0.05) in corn dried at 120 oC than in corn dried at 35 oC. In experiment 2, 40 pigs (20.82 ± 1.74kg) were housed in metabolism crates and allotted to four diets with ten replicate pigs per diet. The four corn-based diets used in experiment 1 were also used in experiment 2. Feces and urine were collected using the marker-to-marker approach with 5-day adaptation and 4-day collection periods. Results indicated that diets containing hard endosperm corn had greater (P < 0.05) ATTD of TDF than diets containing average endosperm corn. The ATTD of GE in hard endosperm corn was also greater (P < 0.05), and concentrations of digestible energy and metabolizable energy in hard endosperm corn were greater (P < 0.01) than in average endosperm corn. Diets containing corn dried at 120 oC had greater (P < 0.05) ATTD of TDF compared with diets containing corn dried at 35 oC; however, drying temperature did not influence the ATTD of GE. In conclusion, endosperm hardness did not influence the digestibility of AA and starch; however, drying corn at 120 oC reduced digestible AA concentrations. Hard endosperm corn had greater ATTD of GE and TDF, but drying temperature did not influence energy digestibility.

Changes in the physicochemical properties of maize endosperm, endosperm fractions, and isolated starches because of nixtamalization

This work focused on the physicochemical changes undergone by maize endosperm during a thermo-alkaline nixtamalization process for the cooking (0 h) and steeping (8 h) steps. The study was performed on the outermost 10%, subsequent 10%, and the remaining 80% of crude, cooked (0 h), and steeped (8 h) endosperm. Calcium content increased mainly in the outermost layers of the endosperm, while the remaining 80% showed no significant changes. The starch granules showed no external damage during cooking and steeping. X-ray analysis revealed that the hard endosperm contained A-type starch with an orthorhombic crystalline structure. Examination of the isolated starches during nixtamalization showed that there is a fraction that does not undergo physicochemical transformation when in contact with water and heat, and this fraction can be referred to as resistance starch. A new methodology using scanning electron microscopy has shown that the pasting properties are determined by the changes in the morphology of the paste.

In vitro propagation of Elaeocarpus gaussenii Weibel: A critically endangered tree of Southern Western Ghats

Elaeocarpus gaussenii Weibel. is a critically endangered tree species in Megamalai Wildlife Sanctuary, Southern Western Ghats, Tamil Nadu, India. This tree has been reported as extinct and collected only by the type specimen due to poor seed germination, endosperm hardness and rigid seed coat. The present study has attempted to develop a micropropagation protocol for E.gaussenii with Woody Plant Medium (WPM) supplemented by different concentrations (0.1–2.0 mg−1) and combinations of BA (6-Benzyl Amino Purine), KIN (Kinetin), TDZ (Thidizuron), IAA (Indole-3-acetic acid), IBA(indole 3-butyric acid) and NAA (Naphthalene acetic acid) alone and various combinations with activated charcoal (1 g−1). The maximum cotyledon germination (97%) was observed on the medium containing KIN + IBA (2.0 + 0.5 mg-1). The best multiple shoot induction (7.6 numbers) with shoot length (8.3 cm) was recorded on IBA + KIN + AD (0.4 + 2.0 mg-1) and maximum root induction (67%) with roots length (3.6 cm) was obtained on WPM with IBA (0.5 mg-1). The rooted plantlets were transferred to pots containing autoclaved garden soil and sand (2:1). About the survival rate, of 80% was successfully recorded in field conditions.

Environment affects starch composition and kernel hardness in temperate maize.

Protein percentage and kernel weight affect the endosperm hardness of maize grains. However, changes in starch composition could also modify kernel hardness, which is often predicted through milling ratio. The objective of this work was to evaluate the relationship between changes in starch composition and endosperm hardness, and to assess the effects of protein content and kernel weight on that relationship. For this, we used information obtained from three temperate hybrids in multi-environmental experiments, as well as experiments conducted under controlled conditions designed to modify starch composition. Milling ratio was determined as maize kernel hardness predictor in both experiments and it was correlated with grain weight and grain composition. In both experiments, milling ratio presented a significant Spearman correlation coefficient with amylose/starch ratio. Milling ratio was significantly related to the amylose/starch ratio using a simple fit with datasets from different experiments and hybrids. Increases in amylose/starch ratio were associated with increases in milling ratio. Starch composition was related to milling ratio variations among hybrids of different aptitude for dry milling through different environments, regardless of protein content. Thus, increases in the amylose/starch ratio were related to increases in the milling ratio. © 2022 Society of Chemical Industry.

Effects of protein digestion on in vitro digestibility of starch in sorghum differing in endosperm hardness and flour particle size

In vitro digestibility of starch in sorghum grains differing in endosperm hardness and flour particle size was investigated. The starch digestibility increased as the particle size of flour decreased, but no clear trend was observed in digestibility of starch in sorghum flours milled from grains with different hardness. The protein matrix affected the digestion of starch. The pH value (2.0 vs. 1.3) was a critical factor affecting protein digestion. Optimum pH (pH 2.0 for pepsin) digested more protein, resulting in a greater digestion of starch. Resistant starch (RS) content was 8.5–26.3% in isolated sorghum starch but higher (10.6–29.5%) in sorghum flours. Protein digestibility decreased after cooking while starch digestibility increased compared to native sorghum flours; disulfide bonds formed between protein molecules. RS content of cooked sorghum flour was much higher without pepsin treatment (16.93–23.99%) than that of cooked sorghum flour with pepsin treatment (4.86–12.53%).

Application of X-ray computed tomography to analyze the structure of sorghum grain

BackgroundThe structural characteristics of whole sorghum kernels are known to affect end-use quality, but traditional evaluation of this structure is two-dimensional (i.e., cross section of a kernel). Current technology offers the potential to consider three-dimensional structural characteristics of grain. X-ray computed tomography (CT) presents one such opportunity to nondestructively extract quantitative data from grain caryopses which can then be related to end-use quality.ResultsPhenotypic measurements were extracted from CT scans of grain sorghum caryopses. Extensive phenotypic variation was found for embryo volume, endosperm hardness, endosperm texture, endosperm volume, pericarp volume, and kernel volume. CT derived estimates were strongly correlated with ground truth measurements enabling the identification of genotypes with superior structural characteristics.ConclusionsPresented herein is a phenotyping pipeline developed to quantify three-dimensional structural characteristics from grain sorghum caryopses which increases the throughput efficiency of previously difficult to measure traits. Adaptation of this workflow to other small-seeded crops is possible providing new and unique opportunities for scientists to study grain in a nondestructive manner which will ultimately lead to improvements end-use quality.

Physical and chemical kernel traits affect starch digestibility and glycemic index of cooked maize flours

Maize starch is an important carbohydrate source in human diet, and its digestion contributes to the postprandial blood glucose level. This article describes in vitro starch digestibility and its relation to endosperm hardness and composition in cooked maize flours. Starch digestion and estimated glycemic index (GI) were significantly (p < 0.05) lower in hard endosperm genotypes (65.1 and 77.3, respectively) than in soft ones (70.7 and 80.7, respectively), and they were negatively correlated (p < 0.05) with specific zein concentrations (total zeins, Z1, Z2, and C1, E, and F zeins). Cooking with sodium sulfite significantly (p < 0.001) increased starch hydrolysis in all genotypes (∼13%), evidencing the impact of disulfide bonds on this attribute. Explored amylose:starch ratios did not impact starch digestibility. Regardless of hardness, fine grinding significantly (p < 0.001) increased total starch digestibility in >30%. Our results focus on specific kernel physicochemical traits for developing maize food products with lower starch digestibility and GI.

Corn kernel hardness, drying temperature and amylase supplementation affect live performance and nutrient utilization of broilers

Drying temperature (DT) of corn can influence its nutritional quality, but whether this is influenced by endosperm hardness is not clear. Two parallel experiments were conducted to investigate the effects of 2 yellow dent corn hybrids with average and hard kernel hardness, dried at 3 temperatures (35, 80, and 120°C), and 2 supplementation levels of an exogenous amylase (0, 133 g/ton of feed) on live performance, starch and protein digestibility, and energy utilization of Ross 708 male broilers. Twelve dietary treatments consisting of a 2 × 3 × 2 factorial arrangement were evaluated using 3-way ANOVA in a randomized complete block design. In Experiment 1, a total of 1,920 male-chicks were randomly allocated to 96 floor pens, whereas 480 day-old chicks were distributed among 96 cages for Experiment 2. At 40 d, interaction effects (P < 0.05) were detected on BWG, FCR, and flock uniformity. Supplementation with exogenous amylase resulted in heavier broilers, better FCR and flock uniformity, only in the diets based on corn dried at 35°C. Additionally, interaction effects were observed on FCR due to kernel hardness and DT (P < 0.01), kernel hardness and amylase supplementation (P < 0.001), and DT and amylase supplementation (P < 0.05). Exogenous amylase addition to the diets based on corn with an average hardness improved FCR up to 2 points (1.49 vs. 1.51 g:g) whereas there was no effect of amylase on FCR of broilers fed diets based on corn with hard endosperm. Total tract retention of starch was increased (P < 0.05) in broilers fed diets based on corn with average kernel hardness compared to hard kernel. Corn dried at 80 and 120°C had up to 1.21% points less starch total tract retention than the one dried at 35°C. Supplementing alpha-amylase resulted in beneficial effects for broiler live performance, energy utilization, and starch total tract digestibility results. Treatment effects on starch characteristics were explored. Corn endosperm hardness, DT and exogenous amylase can influence the live performance of broilers. However, these factors are not independent and so must be manipulated strategically to improve broiler performance.

Wet milling characteristics of export commodity corn originating from different international geographical locations

AbstractBackground and objectivesSoft endosperm corn has better wet milling characteristics but is susceptible to breakage and fracture during transport. The objective of this study is to compare the millability of commodity corn with different endosperm hardness originating from different parts of the world and its economic impact on importers of corn for wet milling.FindingsUS commodity corn generally has a soft endosperm hardness compared to corn from South America as the observed broken corn and foreign material was 0.4–3.4% and higher than other commodity corn exported to the same country. US corn exported to different international markets showed 4–5% higher starch yield compared to South American corn exported to the same market. This translates to an additional revenue of 6.5–9 million USD/year for a 2540 MT/day wet mill plant. [Correction added on 13 April 2021, after first online publication: The value of yield corrected from 100 to 2540.]ConclusionsThe US commodity corn, despite higher breakage, has superior millability and gives higher starch yields compared to corn from other geographies resulting in improved profitability of corn wet milling plants.Significance and noveltyCommodity corn has varying endosperm hardness depending on geography of origin which impacts wet mill starch yield. Corn physical properties were used as an indicator for determining endosperm hardness.

Chemical Composition and Preservation of Mnazi and Its Distillate (Pyuwa)

Coconut palm (Cocos nucifera) is most well-known for the products of its fruit, such as coconut meat, coconut water, coconut milk, and coconut oil. Almost all edible products of the coconut come from the fruit, or “nut” portion of the plant. Some fruit products include desiccated coconut from the hard endosperm of the seed and toddy which, is produced by tapping the sap from inflorescence. Toddy can be boiled to produce coconut sugar (jaggery) or fermented to become an alcoholic beverage (Mnazi). This study explored the quality aspects and preservation of both Mnazi and its spirit (pyuwa) with an aim of providing a cheap alternative beverage for both low and middle income earners. The main volatile compounds that were found in both Mnazi and its spirit include propanol, isoamyl ethanol butanol and acetic acid. In Mnazi, the levels of the volatiles were far much less than 600 mg/l, which is considered the threshold value of acceptability in wine. The absence of methanol and fusel oils in fresh Mnazi makes it possible to compete effectively with beers and alcoholic drinks already in the market. However, its distillate (Pyuwa) cannot be recommended as safe alcohol drink unless further separation is done because of its high levels of fusel oils. The newly developed products: dry, medium dry and sweet brands were stable during the first 4 weeks after production. Assimilation of sucrose and fructose were faster than glucose, with fructose being the fastest.

Expression profile of protein fractions in the developing kernel of normal, Opaque-2 and quality protein maize

Maize protein quality is determined by the composition of its endosperm proteins, which are classified as nutritionally poor zeins (prolamin and prolamin-like) and nutritionally rich non-zeins (albumin, globulin, glutelin-like, and glutelin). Protein quality is considerably higher in opaque-2 mutants due to increased content of non-zeins over zeins. However, the opaque-2 endosperm is soft, which leads to poor agronomic performance and post-harvest infestation. Endosperm modification of opaque-2 had led to the development of Quality Protein Maize (QPM), which has higher protein quality along with hard kernel endosperm. The present study was planned to analyze the expression dynamics of different protein fractions in the endospem of developing maize kernel in normal, opaque-2 and QPM in response to the introgression of endosperm modifiers. Results revealed that albumin and globulin content decreases, whereas, prolamin, prolamin-like, glutelin-like, and glutelin content increases with kernel maturity. It has been observed that opaque-2 mutation affects protein expression at initial stages, whereas, the effect of endosperm modifiers was observed at the intermediate and later stages of kernel development. It has also been noted that prolamin, glutelin, and glutelin-like fractions can be used as quick markers for quality assessment for differentiating QPM varieties, even at the immature stage of kernel development. Overall, the present study implicates the role of different protein fractions in developing and utilizing nutritionally improved maize varieties.