Tannin binding of kafirin and its effects on karirin films

Kafirin, the prolamin protein of sorghum grain, could be extracted from the by-products of the sorghum processing industry and used to make films and coatings for food packaging, in particular to extend the shelf-life of fruits and nuts. Protein-based films can be an environment-friendly alternative to synthetic plastic packaging systems. However, the properties of protein-based films are generally inferior to those of synthetic plastics. Modification can alter the properties of protein-based films. In this project, the interaction between phenolic compounds and kafirin was investigated in relation to their potential to modify kafirin films. A range of phenolic compounds was tested in terms of their ability to bind and complex with kafirin in an in vitro binding assay. The protein-phenolic compound interaction was quantified by haze formation and colorimetric determination of total polyphenol bound. Ferulic acid, catechin and extracted flavonoids from condensed tannin-free sorghum did not complex with kafirin. Tannic acid (TA) and sorghum condensed tannins (SCT) complexed kafirin and formed haze. Thus, T A and SCT were selected as potential modifying agents for kafirin films. TA and SCT were added at up to 20% (w/w tannin to protein basis) during kafirin film casting. Both TA and SCT bound to kafirin in the film. Scanning electron microscopy showed that TA modified films were less porous; and the SCT modified films appeared more globular in structure than unmodified film. Modification with both tannins increased the tensile stress and Young's modulus and decreased the tensile strain of the kafirin films. Oxygen permeability of the modified films was decreased, but no change in the apparent water vapour permeabilty. The T9 of the films increased with increased modification level. SOS-PAGE, FT-IR and Raman spectroscopy were used to study TA and SCT interaction with kafirin. SOS-PAGE revealed a high Mr band for kafirin-SCT complexes which did not enter the separating gel. FT-IR of kafirin complexed tannins and tannin modified films showed a decrease in the absorbance at the frequency of about 1620 cm-1, suggesting a decrease in â-sheet structures. FT-IR results also suggested that the â-sheets of kafirin in dry form were probably changed into random coils during kafirin dissolution to make films. Raman spectra showed a shift in the TA peak at about 1710 cm-1 to about 1728 cm-1 in the kafirin- TA complexes, suggesting participation of the carbonyl groups of TA in TA-kafirin interaction. It is proposed that hydroxyl groups of tannin can form hydrogen bonds with carbonyl groups of random coils of kafirin during film casting. Thus, the carbonyl groups are probably not available to be reorganized into â-sheets. The other possible mode of interaction can be hydrophobic interaction between the aromatic rings of tannins and the pyrrolidine rings of proline. Because tannins have numerous aromatic rings with hydroxyl groups, it is also proposed that they can bind with more than one polypeptide chain at the same time to cross-link kafirin. This cross-linking probably produces a high Mr kafirin-tannin complex that leads to haze. The cross-linking would also lead to lower molecular mobility of modified kafirin films. This could decrease oxygen permeability, probably as a result of decreased free volume. Cross-linking could also be responsible for the increased tensile stress and decreased tensile strain of modified kafirin films. The higher tensile stress of modified• kafirin films suggests that they can have the potential to form stronger coatings around fruit such as litchi fruit to possibly reduce pericarp microcracking as an example, and thus may reduce the pericarp browning of litchi. The lower oxygen permeability of the modified films and the potential antioxidant activity of the tannins suggest that these films can be a good coating to prevent rancidity of nuts.Thesis (PhD (Food Science))--University of Pretoria, 2006.Food Scienceunrestricte

Processing technologies for developing low GI foods –a review

This paper reviews the various technologies employed to lower the glycemic index of foods and provides a future outlook for starchy foods. The glycemic index of foods can be reduced by increasing resistant starch or slowly digestible starch. However, information concerning the parameters/settings and mechanisms by which several technologies can be used are limited. Technologies such as microwave, infrared, ultrasonic, autoclaving, and high hydrostatic pressure can facilitate more interactions between food components, thereby resulting in the formation of various types of resistant starch or slowly digestible starch. Based on the findings of this paper, the use of microwave technology to produce resistant starch has been sufficiently reported in comparison to the other technologies. Given the research done in the last two decades regarding other technologies, there is a need for more research work on optimizing the parameters or processing conditions for thermal and non-thermal technologies in order to produce low GI starch and starchy foods. There is limited work done on combination treatments that can effectively develop low GI foods. The data provided for glycemic index and starch digestibility kinetics is mostly from in vitro studies.European Union’s Horizon 2020 research and innovation programme.https://onlinelibrary.wiley.com/journal/1521379xhj2023Consumer ScienceFood Scienc

Functionality of maize, wheat, teff and cassava starches with stearic acid and xanthan gum

Consumer concerns to synthetic chemicals have led to strong preference for ‘clean’ label starches. Lipidand hydrocolloids are food friendly chemicals. This study determines the effects of stearic acid and xan-than gum alone and in combination on the functionality of maize, wheat, teff and cassava starches. Anincrease in viscosity was observed for all starches with stearic acid and xanthan gum compared to thecontrols with cassava having the least increase. A further increase in viscosity was observed for the cerealstarches with combination of stearic acid and xanthan gum. Stearic acid reduced retrogradation, resultingin soft textured pastes. Combination of stearic acid and xanthan gum reduced the formation of type IIbamylose–lipid complexes, syneresis, and hysteresis in cereal starches compared to stearic acid alone. Acombination of stearic acid and xanthan gum produce higher viscosity non-gelling starches and xanthangum addition increases physical stability to freezing and better structural recovery after shear.National ResearchFoundation (NRF) and DST/NRF Centre of Excellence in Food Secu-rity, Winter Cereal Trust (WCT) and University of Pretoria.http://www.elsevier.com/locate/carbpol2017-01-31hb201

Nutritional quality of wet and dry processed Moringa oleifera Lam. leaves : a review

Moringa oleifera: Lam. is a plant species that has found a multitude of applications from health, water clarification and as a food source. In particular, the tree leaves have been consumed in various countries were it is incorporated in the local diet. The advent of food processing technologies have alluded to various methods to process, preserve and extend the shelf-life of fresh produce. This review focuses on the nutrient quality of M. oleifera leaves processed using energy-efficient processing technologies such as sun drying, blanching, boiling and fermentation.The National Research Foundation.https://www.tandfonline.com/loi/lfri20hj2023Consumer ScienceFood Scienc

Current status of xylooligosaccharides : production, characterization, health benefits and food application

BACKGROUND : Functional foods are receiving high interest and attracting global attention due to their therapeutic health benefits. Xylooligosaccharides (XOS) are potential prebiotics that has attained commercial interest due to their prospective application in the food industry and its beneficial effects on human wellness. The demand to create alternate natural sources is steadily increasing to meet the consumer and industry needs for safe foods. SCOPE AND APPROACH : The review summarizes the various strategies employed in xylan extraction, XOS production (chemical and enzymatic) and characterization. The study also critically views the physiological importance and biological effects described through various in vitro and in vivo intervention studies. The technological properties, food-based applications and the future perspectives of XOS are presented. KEY FINDINGS AND CONSLUSIONS : A better utilization of XOS to exert a positive impact on health would help to the functional foods and nutraceuticals future markets.UP Post-Doctoral Fellowship Programme, University of Pretoria, Republic of South Africa, and DST-NRF CoE in Food Security grant.https://www.elsevier.com/locate/tifshj2022Consumer ScienceFood Scienc

Morphology, physical, chemical, and functional properties of starches from cereals, legumes, and tubers cultivated in Africa : a review

In Africa a variety of indigenous cereals, legumes, and tubers are cultivated as starchy food crops. These include sorghum, millet species including pearl millet, finger millet, teff, and white and black fonio, and African rice as cereals; cowpea, Bambara groundnut, African yambean and West African locust bean as legumes; and Zulu round potato and the Livingstone potato as tubers. Many of these plants are considered as “lost crops of Africa.” This paper critically reviews the literature on the physical, chemical, and functionality of their starches. Information is essentially limited to the native starches of sorghum, some millets, and cowpea. Livingstone potato starch information is essentially absent. Notable characteristics of African starches include that teff and finger millet have compound starch granules. Some of the starches have unique properties which could be valuable. The very small granular size of teff and its functional properties can be exploited as a fat replacer. The high retrogradation of cowpea starch has potential in gluten-free pasta and noodles. Nonfood applications for the African starches should be considered in the growing mining and oil industries in Africa.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1521-379Xhttp://www.starch-journal.comhj201

Background, limitations, and future perspectives in food grade microemulsions and nanoemulsions

The interest towards microemulsions and nanoemulsions, the colloidal systems utilized to encapsulate bioactive compounds, is constantly increasing in food industries. Major characteristics of microemulsions and nanoemulsions should be assessed to better differentiate these two systems. Limitations and restrictions being imposed on the development of food-grade microemulsions and nanoemulsions should be addressed to improve their significant role in the food and beverage industry. Food studies should consider practical issues more thoroughly and apply effective inexpensive measures to minimize surfactant losses and improve surfactant recovery to bridge the gap between laboratory experiments and industrial processes.The DSI [Department of Science and Innovation] and National Research Foundation (NRF) Centre of Excellence in Food Security.https://www.tandfonline.com/loi/lfri20hj2023Consumer ScienceFood ScienceSDG-02:Zero Hunge

Effects of gamma irradiation and stearic acid, alone and in combination, on functional, structural, and molecular characteristics of high amylose maize starch

The effects of gamma irradiation and stearic acid, alone and in combination, on functional, structural, and molecular characteristics of high amylose maize starch (Hylon VII, 60% amylose) were studied. Stearic acid (0, 1.5, and 5%) was added to Hylon VII starch, and then irradiated at 0, 30, and 60 kGy. Gamma irradiation significantly (p 0.05) increased solubility, water absorption capacity, and oil absorption capacity as well as decreased swelling power (at 90 and 95°C) of Hylon VII starch. These changes related well with increased amylose and decreased amylopectin content, decreased MW, and decreased transition endotherms of the starches due to gamma irradiation. Stearic acid addition significantly increased (p 0.05) water and oil absorption capacities, relative crystallinity as well as decreased solubility and swelling power of Hylon VII. Gamma irradiation had more effect on the molecular structure of Hylon VII compared with stearic acid. Gamma irradiation alone and with stearic acid did not seem to change the XRD pattern and microstructure of Hylon VII. The similar XRD pattern and morphology observed for irradiated and non-irradiated Hylon VII suggests that gamma irradiation depolymerizes amylose, and amylopectin mostly in the amorphous region of the starch to produce less branched or unbranched amylopectin. Gamma irradiation with stearic acid has potential in Hylon VII modification.This research was funded in part under the International Atomic Energy Agency (IAEA) Technical Cooperation (TC) project and Ghana Atomic Energy Commission (GHA/0/010, Government of Ghana).http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1521-379Xhb201

Cooking quality, nutritional and antioxidant properties of gluten-free maize – orange-fleshed sweet potato pasta produced by extrusion

Maize and orange-fleshed sweet potato (OFSP) composite (100:0, 50:50, 70:30, 80:20) flours were extruded into pasta using a twin-screw extruder. The cooking quality, textural and nutritional properties of the pasta were assessed. An increase in the proportion of OFSP flour added increased the cooking loss but decreased cooking time and water absorption capacity of pasta. The dietary fibre in the OFSP flour caused a loosening of the compact structure of the pasta, disrupting the compact protein-starch matrix of maize, resulting in higher cooking loss and sticky pasta. Extruded pasta had low cooking time due to pre-gelatinized starch, which promotes greater water absorption and heat dissemination during cooking. Extruded pasta samples had lower betacarotene, probably due to cis-trans isomerization, fragmentation, and oxidative decomposition, but the pasta showed higher antioxidant properties, likely due to Maillard reaction and caramelization products with reducing properties. These results indicate that OFSP can be composited with maize flour and extruded to produce good quality and nutritious gluten-free pasta.The DSI-NRF Centre of Excellence in food security (South Africa).https://www.elsevier.com/locate/lwtam2023Consumer ScienceFood Scienc

Development of hemp seed oil nanoemulsions loaded with ascorbyl palmitate : effect of operational parameters, emulsifiers, and wall materials

DATA AVAILABILITY : Data will be made available on request.The perceived health properties of hemp seed oil, as one of the few plant-based sources of omega-3 and omega-6 fatty acids with an ideal ratio of 1:3, suggest its incorporation in food-grade emulsions to improve its water solubility and oxidative stability. The current research's main aim was nanoemulsification of hemp seed oil using the oil-in-water emulsification method followed by ultrasonication. The entrapment efficiency of the nanoemulsions for antioxidant ascorbyl palmitate and its impact on oxidative stability of the oil was also evaluated. Gum arabic: maltodextrin in 75:25 ratio could result in nanoemulsion with entrapment efficiency of 97.10 % for ascorbyl palmitate and radical scavenging activity of oil-soluble bioactives of 92.13 %. Moreover, incorporation of ascorbyl palmitate could effectively retard the oxidation, specifically in nanoemulsions containing gum Arabic. The optimum formulation of nanoemulsion having an average droplet size of 293 nm can be applied as an ideal vegetarian source of omega-3 fatty acids.The DSI (Department of Science and Innovation) and NRF (National Research Foundation) Centre of Excellence in Food Security.http://www.elsevier.com/locate/foodchemhj2023Consumer ScienceFood ScienceSDG-02:Zero Hunge