Holistic View of Starch Chemistry, Structure and Functionality in Dry Heat-Treated Whole Wheat Kernels and Flour

Heat treatment is used as a pre-processing step to beneficially change the starch properties of wheat flour to enhance its utilisation in the food industry. Heat-treated wheat flour may provide improved eating qualities in final wheat-based products since flour properties predominantly determine the texture and mouthfeel. Dry heat treatment of wheat kernels or milled wheat products involves heat transfer through means of air, a fluidising medium, or radiation—often resulting in moisture loss. Heat treatment leads to changes in the chemical, structural and functional properties of starch in wheat flour by inducing starch damage, altering its molecular order (which influences its crystallinity), pasting properties as well as its retrogradation and staling behaviour. Heat treatment also induces changes in gluten proteins, which may alter the rheological properties of wheat flour. Understanding the relationship between heat transfer, the thermal properties of wheat and the functionality of the resultant flour is of critical importance to obtain the desired extent of alteration of wheat starch properties and enhanced utilisation of the flour. This review paper introduces dry heat treatment methods followed by a critical review of the latest published research on heat-induced changes observed in wheat flour starch chemistry, structure and functionality.

Characteristics of avocado (Persea americana) and kluwih (Artocarpus camansi) seeds starch with different extraction methods

Seed from avocado (Persea Americana) and kluwih (Artocarpus camansi) fruit are waste and by product from processing fruit. Due to the high starch content from both seeds, there are many extractions process have been applied. The immersed raw material in sodium metabisulfite solution affected to starch properties. The purpose of this study is to characterize of starch extracted with and without immersed in sodium metabisulfite solution. The results showed that the starch yield by immersed in alkaline solution was 21.6% for avocado seed starch and 24.4% for kluwih seed starch, while yield without immersed in sodium metabisulfite solution was 17.5% and 18,2% for avocado seed starch and kluwih seed starch, respectively. The starch content with sodium metabisulfite immersion process of avocado seed and kuwih seed were 79.26% and 72.62%, respectively. Meanwhile without the immersion process resulted starch of 75.13 and 67.30%, in avocado seed starch and kluwih seed starch, respectively. Furthermore, XRD and FTIR analysis were also carried out on starch to see the crystallinity character and functional groups contained in the extracted starch.

Near Infrared Spectroscopic Evaluation of Starch Properties of Diverse Sorghum Populations

Starch, mainly composed of amylose and amylopectin, is the major nutrient in grain sorghum. Amylose and amylopectin composition affects the starch properties of sorghum flour which in turn determine the suitability of sorghum grains for various end uses. Partial least squares regression models on near infrared (NIR) spectra were developed to estimate starch and amylose contents in intact grain sorghum samples. Sorghum starch calibration model with a coefficient of determination (R2) = 0.87, root mean square error of cross validation (RMSECV) = 1.57% and slope = 0.89 predicted the starch content of validation set with R2 = 0.76, root mean square error of prediction (RMSEP) = 2.13%, slope = 0.93 and bias = 0.20%. Amylose calibration model with R2 = 0.84, RMSECV = 2.96% and slope = 0.86 predicted the amylose content in validation samples with R2 = 0.76, RMSEP = 2.60%, slope = 0.98 and bias = −0.44%. Final starch and amylose cross validated calibration models were constructed combining respective calibration and validation sets and used to predict starch and amylose contents in 1337 grain samples from two diverse sorghum populations. Protein and moisture contents of the samples were determined using previously tested NIR spectroscopy models. The distribution of starch and protein contents in the samples of low amylose (<5%) and normal amylose (>15%) and the overall relationship between starch and protein contents of the sorghum populations were investigated. Percent starch and protein were negatively correlated, low amylose lines tended to have lower starch and higher protein contents than lines with high amylose. The results showed that NIR spectroscopy of whole grain can be used as a high throughput pre-screening method to identify sorghum germplasm with specific starch quality traits to develop hybrids for various end uses.

Collection, Characterizaton and Conservation of Genetic Resources of Yam Cultivars From Ekiti State, Nigeria

This study was initiated to restore the genetic resources of yam which had been decimated in a core yam-producing community in Ekiti State, Southwestern Nigeria. Twenty cultivars, consisting of Dioscorea rotundata, D. cayenensis, D. alata, and D. dumetorum were identified, collected, characterized and multiplied using an On-farm Participatory Method. The yam cultivars were characterized for quality and yield of pounded yam (iyan) as well as starch properties. They were later conserved in the Teaching and Research Farm of the Obafemi Awolowo University Ile-Ife.Morphological characterization separated Dioscorea alata (Ewura) by its winged vines while Dioscorea dumetorum (Esuru) was separated by its pubescent spines, trifoliate leaf with acute apex and base and the clustered, irregularly-shaped tuber. All the tubers of the yam cultivars had high storability. Pounded yam quality rated the Ikumo and Ajimokun cultivars as best while Odo was rated average and this was attributed to the swelling properties and amylose content of these cultivars. Yam cultivars with high granules had low swelling capacities. The Brittle Fraction Index of the starch from all the cultivars was lower than 1.0 explaining why the iyan they produced had no crust on the surface and kept for long hours after preparation.From this study, it was concluded that the local yam cultivars collected represent the core of yam genetic resources for utilization in the region. These cultivars are therefore recommended for prioritization in further studies on propagation, conservation and improvement so that a narrow genetic base of cultivars is not encouraged, for example, by promoting cultivars whose vines perform well in tuberization.

Potato Starch Extrusion and Roasting with Apple Distillery Wastewater as a New Method for Resistant Starch Production

Potato starch was extruded and roasted with apple distillery wastewater to produce starch esters substituted with malic acid residues. The starch esterification degree was higher at the higher roasting temperatures. Starch modification contributed to its darker color, its increased resistance to the action of amylolytic enzymes, and its decreased solubility and heat of phase transition. The changes in the other starch properties examined depended on the extrusion and roasting temperatures. The process, which was conducted without a chemical agent—in this case, the process of starch extrusion and roasting with apple distillery wastewater—should be deemed a novel method for resistant starch production.

Engineering Properties of Sweet Potato Starch for Industrial Applications by Biotechnological Techniques including Genome Editing

Sweet potato (Ipomoea batatas) is one of the largest food crops in the world. Due to its abundance of starch, sweet potato is a valuable ingredient in food derivatives, dietary supplements, and industrial raw materials. In addition, due to its ability to adapt to a wide range of harsh climate and soil conditions, sweet potato is a crop that copes well with the environmental stresses caused by climate change. However, due to the complexity of the sweet potato genome and the long breeding cycle, our ability to modify sweet potato starch is limited. In this review, we cover the recent development in sweet potato breeding, understanding of starch properties, and the progress in sweet potato genomics. We describe the applicational values of sweet potato starch in food, industrial products, and biofuel, in addition to the effects of starch properties in different industrial applications. We also explore the possibility of manipulating starch properties through biotechnological means, such as the CRISPR/Cas-based genome editing. The ability to target the genome with precision provides new opportunities for reducing breeding time, increasing yield, and optimizing the starch properties of sweet potatoes.