Effects of electron beam irradiation on storability of brown and milled rice
Xiaohu Luo, Yulin Li, Dan Yang, et al
The effects of electron beam irradiation (EBI) treatment on the freshness and quality of brown and milled rice at different irradiation doses were investigated. The colors of brown rice (P?>?0.05) and milled rice (P?<?0.05) slightly changed after 5?kGy irradiation. After irradiation, the viscosities and amylose contents of the samples decreased (P?<?0.05), crystal forms remained unchanged, but crystallinities decreased (P?<?0.05). The microstructures of the samples did not change according to the results of the scanning electron microscopy. During the 120-day storage process, the free fatty acids of the irradiated samples increased at a slower rate than the non-irradiated samples did. Lipase activity was inhibited effectively, and the total viable bacterial count was significantly reduced (P?<?0.05). Results indicated the potential of EBI to improve the quality and extend the shelf lives of brown and milled rice during storage.
Journal of Stored Products Research,2019(2): 22-30
Effect of Light Exposure on the Quality and Phenol Content of Commercial Extra Virgin Olive Oil during 12‐Month Storage
Amelia de la Torre‐Robles, Celia Monteagudo, Miguel Mariscal‐Arcas,et al
Storage conditions influence the maximum time for which the composition and sensory characteristics of olive oils can be guaranteed. The purpose of this research was to study the quality and phenol content of extra virgin olive oil (EVOO) after storage for 1 year in different types of containers under darkness or light. Three Spanish cultivars with quantitatively different phenol contents were selected for the study. Storage under light conditions impaired the physicochemical and sensorial properties of the three cultivars, and reduced total phenolics, but there was an increase in hydroxytyrosol and tyrosol concentrations. It also markedly decreased their total phenolic content, especially when kept in polyethylene containers exposed to light, with reductions ranging from 4.28% for vanillic acid in Picual oils stored in dark glass containers under dark conditions to 97.82% for ferulic acid in Arbequina oils stored in polyethylene containers under light conditions. There was a reduced concentration of flavonoid and lignan concentrations after 1 year of storage, with the greatest decrease (98.01% of initial content) being observed for in the flavonoid apigenin. These results indicate that EVOO should be stored in dark glass containers under dark conditions for the optimal preservation of its quality and phenol content.
Evaluation of postharvest preservation strategies for stored wheat seed in Ethiopia
Karta Kaske Kalsa, Bhadriraju Subramanyam, Girma Demissie,et al
Limited information exists on postharvest preservation strategies of stored wheat in Ethiopia. The present study was conducted to evaluate the effectiveness of on-the shelf postharvest storage strategies of stored wheat in the country. The experiment consisted of eight treatments; (1) metal silos, (2) Purdue Improved Crop Storage (PICS) bags, (3) Super GrainPro bags, (4) industrial filter cake dust applied to wheat in polypropylene bag, (5) plastic drums, 6) Triplex applied to wheat in polypropylene bag, 7) Triplex applied to wheat in plastic drum, and 8) polypropylene bag as control. Measurements of oxygen and carbon dioxide levels, live adults of insects per kg, percentage seed damage, and percentage of weight loss, germination and seedling vigor were determined every two months for six months. Results indicated that storage strategies such as PICS and Super GrainPro bags, filter cake, Triplex, and plastic drums led to a significantly lower live insect density compared to the control. Besides, Triplex and filter cake dust or use of hermetic bags also resulted in a significantly lower rate of seed weight loss (%) compared to the control. After six months of storage, means?±?SD germination of seed from the polypropylene bag (control) had decreased to 68.0?±?6.1% while wheat in all other storage strategies exhibited means?±?SD germination capacity ranging from 92.0?±?3.6% to 98.0?±?1.0%. The present results demonstrate the potential of preserving stored wheat without relying on synthetic insecticides by using hermetic bags, filter cake, and Triplex, with advantages over traditional strategies used by smallholder farmers in Ethiopia. We recommend that hermetic bags, filter cake dust, and Triplex powder should be promoted for use by farmers for the postharvest preservation of their stored wheat.
Journal of Stored Products Research,2019(2):53-61
Post-harvest kernel discoloration and fungi activity in long-grain hybrid, pureline and medium-grain rice cultivars as influenced by storage environment and antifungal treatment
Z. Mohammadi Shad, G.G. Atungulu
Milled rice grade is diminished as the quantity of discolored kernels increases. This study evaluated the magnitude of kernel discoloration and relationship to fungal growth for long-grain hybrid (XL 753), long-grain pureline (Roy J.) and medium-grain (Titan) rice, exposed to storage moisture contents (MCs) of 16 and 21%, wet basis, temperatures of 20, 30, 40?℃, and durations up to 16 weeks. Impact of postharvest treatments with the antifungal agents, natamycin and sodium chloride, on rice discoloration and fungal growth was compared with untreated (control) samples. Subsamples were taken every four weeks to determine total fungal counts, discoloration, and water activity. Rice stored at 40?℃ had six-to eleven-times more discoloration than at 20?℃. Increased storage duration significantly increased discoloration. Discoloration was not different between MC levels. Discoloration was significantly lower by sodium chloride treatment, while natamycin was not effective compared to control. Rice samples treated with sodium chloride also had significantly less water activity (mean aw?=?0.73) compared to samples treated with natamycin (mean?=?0.84) and control samples (mean?=?0.83). Hybrid rice had significantly less discoloration compared to pureline and medium-grain. Fungal counts were similar across all cultivars. Increasing temperature and duration decreased fungal count. An inverse relation between fungi and discoloration suggests microbe activities did not explain discoloration. The findings provide important information to growers and processors on conditions necessary to maintain rice quality.
Journal of Stored Products Research,2019(2):91-99
Efficacy of heat treatment on phosphine resistant and susceptible populations of stored product insects
P. Agrafioti, C.G. Athanassiou, Bh. Subramanyam
In this study we evaluated the efficacy of heat treatment on phosphine resistant and susceptible populations of stored product insects at twenty three different commercial facilities in Greece. Heat treatments were carried out by using special equipment, such as Therminate, TempAir and ThermoNox, applied alone or in combination. The overall temperature range was between 33 and 55?℃ and the duration of the heat treatments was between 20 and 39?h. Adults of the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), and the sawtoothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae), were used in the experiments. The field populations were collected from different storage facilities in Greece and were characterized as resistant populations by using the Detia Degesch Phosphine Tolerance Test Kit. Insect mortality was measured at the termination of each trial. Then, the vials were kept in incubator chambers at 25?℃ and 65% relative humidity and 65?d later the progeny production was measured in the treated substrate. In light of our findings, in the vast majority of the cases, complete control was observed for both resistant and susceptible populations at all facilities. In general, in the few cases where survival and progeny production was recorded, there was no specific trend towards specific species or population. Overall, based on the current results, heat treatment can be used by the industry as an alternative method for the control of phosphine-resistant adults of R. dominicaand O. surinamensis.
Journal of Stored Products Research,2019(2):100-106
Impact of storage structures on moisture content, insect pests and mycotoxin levels of maize in Ghana
J.K. Danso, E.A. Osekre, G.P. Opit,et al
Insect pests and fungal pathogens can cause extensive product losses and pose health risks in sub-Saharan Africa. In this experiment, maize stored as de-husked cobs or shelled maize in a ventilated crib and a metal bin, and in bags in warehouses, was monitored monthly in Ghana from October of 2015 to December of 2015 (the major season) and from January to April of 2016 (the minor season). Temperature, moisture content, insect pests, and associated damage were assessed monthly, and samples were taken in October, December, January, and April for mycotoxin analyses. Moisture content, which ranged from 9 to 15% during the year was occasionally greater in the bin and warehouse compared to the crib, and greater in months associated with the major season compared to other months. Temperatures varied with season but were generally warmer in the bin compared to the warehouse and crib. The predominant insect collected was Sitophilus zeamais(Motschulsky), with the lowest populations in the crib, but in each structure the populations were about 10x greater in the major season compared to the minor season. Sitotroga cerealella (Olivier) was the second most-prevalent species, but populations of this species were greater in the crib compared to the bin or warehouse. Scattered populations of other stored product insects were collected from the maize samples and in pheromone traps. Percentage insect damaged kernels (IDK) and weight loss were also greater in samples from months where S. zeamais was present. Aflatoxin was above 10?ppb only in the warehouse in December, while fumonisin levels in all the storage structures were <0.5?ppm for all months. Results show that maize stored during the major season in Ghana is at risk from insect damage, and metal bins could be utilized more frequently for storage.
Journal of Stored Products Research,2019(2):114-120
Particle size effect of rice flour in a rice-zein noodle system for gluten-free noodles slit from sheeted doughs
Myeongseon Kim,Imkyung Oh,Sungmin Jeong,Suyong Lee
Zein was incorporated at 5% (w/w) to high amylose rice flours with different particle sizes (80–100, 100–140, and 140–250?μm) and the rice flour-zein composites were utilized to generate gluten-free noodles slit from sheeted doughs. Rice flours with smaller particle size showed higher starch damage whereas they had greater water hydration properties and higher pasting parameters. In addition, the fine particle size contributed to the elastic properties of the rice-zein composites. The ability of zein to generate a viscoelastic protein network at above its glass transition temperature, successfully produced gluten-free rice sheeted doughs regardless of particle size that could be slit into long and thin noodle strands without gluten. The rice-zein noodles with larger particle sizes had a rough surface while the noodle surface became smooth and flat at decreasing particle sizes. The noodle samples with rice flour having an intermediate particle size (100–140?μm) showed the highest values of maximum resistance and extensibility to extension that consequently contributed to the decreased cooking loss. This study provided a new opportunity for food manufacturers to improve the qualities of gluten-free rice noodles made from sheeted doughs by controlling particle size.
Journal of Cereal Science，2019,86(3):48-53
Kernel properties and popping potential of Chapalote, a Mexican ancient native maize
María Gricelda Vázquez-Carrillo, David Santiago-Ramos, Juan de Dios Figueroa-Cárdenas
Chapalote is a Mexican ancient maize landrace with popping characteristics that have not been studied. This work aimed to study the kernel physicochemical properties and their relationship with popping properties of 10 Chapalote accessions. Two popping methods, cooking pan and hot-air popping, were tested. A commercial popcorn sample was used for comparison purposes. Hot-air popping led to higher expansion volume, less unpopped kernels, and bigger popped kernels than traditional popping. Among Chapalote samples, one accession (612) had the best popping properties, but none of them popped similarly to the commercial popcorn. This behavior may be related to the non-breeding origin of Chapalote accessions contrasting with the improved hybrids. Smaller kernels containing more pedicel, pericarp, and vitreous endosperm led to higher expansion volume and lower unpopped kernels. In air-popping, higher α-zein content, and bigger starch granules with less crystallinity influenced positively the popping properties, mainly the air bubbles and popped kernel size. Pericarp thickness was not a crucial factor in popping performance. Some Chapalote accessions with good popping quality could be an important source of germplasm in breeding programs for the development of modern popcorn varieties with distinct properties, which may help to avoid the extinction of this landrace.
Journal of Cereal Science，2019,86(3): 69-76
Effect of egg yolk lipids on structure and properties of wheat starch in steamed bread
Shangyuan Sang, Yuting Chen, Xiao Zhu, et al
Hen egg is commonly used in bakery products, such as cakes, bread, and cookies, which are all abound with starch. Egg yolk lipids (EYL) with different polarity can affect the structure and properties of starch, as well as steamed bread-making performance. EYL were mainly divided into neutral lipids, cholesterol and phospholipids with increasing polarity by thin layer chromatography. Results from Rapid Visco Analyzer showed that both cholesterol and phosphatidylcholine (PC) promoted gelatinization of wheat starch, but neutral lipids did not. Texture analysis indicated that hardness of wheat starch gels significantly decreased only with PC, caused by an increasing in the spacing between double helical cross-links as characterized by differential scanning calorimetry. Furthermore, a single helix structure of amylose-PC complex was confirmed by molecular simulation and X-ray diffraction. Finally, yolk can be used to soften the firmness of starch-based food such steamed bread.
Journal of Cereal Science，2019,86(3): 77-85
Effect of extraction conditions on phenolic content, anthocyanin content and antioxidant activity of bran extracts from Thai rice cultivars
The bran of two cultivars of Thai non-glutinous rice, namely Khao dawk mali 105 (white rice) and Hom nil (purple rice); and two varieties of Thai glutinous rice, namely Kiaw Ngu (white rice) and Leum Pua (dark purple rice) were assessed regarding their compositions, total phenolic content and antioxidant activity. The aims of this research were to (1) identify the major components of the various kinds of Thai rice bran and their properties, (2) evaluate the effect of extracting solvent on the chemical compositions and antioxidant activity of extracts, and (3) optimize the appropriate extraction temperature and extraction time for obtaining high-efficiency extracts. The amounts of 3 major groups of bioactive compounds, including phenolic acids, flavonoids and anthocyanins, were investigated using high-performance liquid chromatography. The highest values of phenolic acids, flavonoids, anthocyanins, total phenolic content, and antioxidant activity based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP) assays were detected in extracts obtained using 65% (v/v) ethanol. The extraction process conducted at 60?℃ for 60?min provided the highest values of bioactive compounds, total phenolic content, DPPH radical scavenging activity and FRAP.
Journal of Cereal Science，2019,86(3):86-91
Effect of rice, pea, egg white and whey proteins on crust quality of rice flour-corn starch based gluten-free breads
Joana Pico, Montserrat P. Reguilón, José Bernal, Manuel Gómez
Gluten-free bread crusts are known for their crumbly texture, light colour, poor nutritional quality and weak aroma. The objective of this research was to improve crust quality of gluten-free breads by the addition of rice, pea, egg white and whey proteins to the bread formulation in two levels (5% and 10%). Moisture, water activity, thickness, microstructure, texture, colour and volatile compounds were measured. A 99% negative significant correlation between spatial frequency of structural ruptures and crust moisture content was found. Results from texture analysis indicated that animal and 10% pea protein crusts were less crispy than control. Moreover, crust microstructure of animal protein bread was very different from control and vegetal protein crusts. Animal and vegetal protein crusts showed darker colour than control and the darkest was obtained from whey protein inclusion. With respect to the volatile profiles, rice protein crusts had the highest content of 2-acetyl-1-pyrroline while whey protein crusts had high level of pyrazines, which was in concordance with their dark colour. However, whey protein and, above all, rice protein also increased the content of volatile compounds from lipids oxidation. Thus, the suitable proportion between rice and whey protein should be found to achieve the most pleasant aroma.
Journal of Cereal Science，2019,86(3): 92-101
Improving dry‐fractionated corn fermentation by supplementation of corn germ meal and pasta mill feed from agro‐food industries
Deepak Kumar,Vijay Singh
Separation of germ from corn using dry fractionation in modified dry‐grind processes results in the sluggish and incomplete fermentation of remaining corn because of nutrient deficiency for yeast. This study investigated the use of two low‐value co‐products, germ meal from corn wet milling and mill feed from pasta manufacturing, as additives to improve the fermentation of corn grits.Addition of 5% germ meal or 2.5% mill feed in corn grits resulted in the complete (no residual glucose) and faster fermentation, compared to 4.3% residual glucose during fermentation of only corn grits. Final ethanol yield (0.51 L/kg) was about 22% higher compared to control (0.42 L/kg). Increase in supplementation (10% of grits) further increased the fermentation rates, however, led to similar final ethanol concentrations and ethanol yields.Both germ meal and pasta mill feed can improve fermentation rate and efficiency of dry‐fractionated grits and avoid the need for expensive supplements or enzymes.
Effect of xanthan gum on dough properties and bread qualities made from whole wheat flour
Lauren Tebben,Yonghui Li
This study aimed to determine the effect of xanthan gum on whole wheat dough and bread, especially dough rheological properties, gluten structures, loaf volume, and bread texture and staling.Xanthan gum increased the water absorption and mixing time for whole wheat dough as determined by mixograph. Xanthan gum altered dough rheology as evaluated through the Kieffer extensibility test, Chen–Hoseney stickiness test, and compression test employed for extensional viscosity calculation. Gluten secondary structure was analyzed by FTIR spectroscopy. Changes to glutenin and gliadin extractability were measured by RP‐HPLC. Specific loaf volume increased from 3.74 to 4.38 cm3/g. Crumb hardness of fresh bread decreased more than twofold by xanthan inclusion. Hardness after 48 hr of bread storage was also lower than the control, but the rate of hardness increase was not reduced. Moisture loss over 48 hr decreased for 0.6% and 1.0% xanthan gum. DSC revealed that xanthan gum decreased amylose–lipid complexation, but did not affect amylopectin retrogradation.Xanthan gum altered the rheological properties of whole wheat dough, increased whole wheat bread volume, and decreased the hardness of both fresh and stored bread. Future research could examine the effect of xanthan gum in combination with other crumb softeners and antistaling agents, in order to achieve both an increase in loaf volume and a decrease in staling for whole wheat bread.
Oil powders stabilized with soy protein used to prepare oil-in-fat dispersions
Iris Tavernier, Bart Heyman, Paul Van der Meeren, et al
We report on the use of a soy protein stabilized, spray-dried oil powder as a vehicle for the introduction of unsaturated liquid oil in a continuous fat matrix. The spray dried oil powder was mixed with the molten continuous fat phase in concentrations of 30, 40, 50 and 60% of powder. The static crystallization of the continuous fat phase resulted in the formation of oil-in-fat dispersions, as was visualized with light microscopy and cryo-SEM. The isolation of the liquid oil in the internal oil droplets ensured that the continuous fat phase dominated the structuring of these newly developed oil-in-fat dispersions, which was rheologically demonstrated with amplitude sweeps. The elastic modulus of a 40% oil-in-fat dispersion (G’LVR=3.54±0.731*105?Pa) was not significantly different from that of the undiluted fat phase (G’LVR=4.55±1.87*105?Pa), even though the dispersion contained 40% more unsaturated oil. However, thixotropic tests revealed that the oil-in-fat dispersions are shear sensitive which can limit their applicability. The recovery percentage after shear of the undiluted fat was 39%, while the 30 and 40% oil-in-fat dispersion had a maximal recovery percentage of 19%.These findings provide a potential approach to reduce the saturated fat content of fat-based food products using only food-grade ingredients and traditional food processing techniques. Nevertheless, further optimization of the emulsion formulation and preparation and of the spray drying process is essential to improve the shear stability of these oil-in-fat dispersions.
Journal of Food Engineering,2019,244:136-141
High moisture extrusion of wheat gluten: Modeling of the polymerization behavior in the screw section of the extrusion process
Valerie L. Pietsch, Frederic Schöffel, Matthias Rädle, et al
Thermomechanical treatment in the screw section of the extrusion process has a major impact on wheat gluten polymerization and subsequent structuring mechanisms that lead to the formation of anisotropic product textures. Therefore, this study presents a modeling approach that allows to predict wheat gluten polymerization at non-isothermal conditions by measuring material temperatures and temperature variations along the screws section. Since no study exists considering modeling of the reaction behavior of plant proteins during extrusion processing, the predictive accuracy of the non-isothermal approach was compared to another approach assuming isothermal conditions by measuring material temperature at die exit and mean residence time. Results show that the approach considering non-isothermal conditions significantly improved the predictive accuracy of wheat gluten polymerization as compared to the results from isothermal modeling.
On the feasibility of metal oxide gas sensor based electronic nose software modification to characterize rice ageing during storage
Hassan Rahimzadeh, Morteza Sadeghi, Mahdi Ghasemi-Varnamkhasti,et al
The aroma change of aromatic and non-aromatic rice was traced during storage using electronic nose (E-nose). Various steady-state and transient features were derived from the adsorption and desorption phases of the E-nose responses to characterize the ageing process and classify the storage durations. Principal component analysis was utilized to analyse the ageing in terms of seven classes related to the storage duration of 6 months. The aromatic samples followed a specific pathway in its timeline with separately distinctive grouping, revealing the reduction of ageing indices. The aromatic rice underwent crucial changes in its volatile compounds, mainly in the early stages of storage. While, confused grouping of the non-aromatic rice proved its stability due to less diverse range of the aroma compounds. Several artificial neural networks, namely back propagation (BP), radial basis function (RBF), and learning vector quantization (LVQ) were used to classify the storage durations. For the aromatic samples, full classification was achieved by using all the networks. For the non-aromatic rice, the developed RBF and LVQ networks represented full classification by using the features of rise time and polynomial curve fitting parameters. It is concluded that the E-nose system along with the developing methods could be utilized to control the rice ageing.
Journal of Food Engineering,2019,245:1-10
Determining damage levels in wheat caused by Sunn pest (Eurygaster integriceps) using visible and near-infrared spectroscopy
Paul Armstrong, Elizabeth Maghirang, Mehmet Ozulu
A commercial near-infrared (NIR) instrument for bulk samples and a modified Single Kernel Near-Infrared (SKNIR) instrument equipped with a visible or NIR spectrometer were studied as a way to measure damage levels caused by Sunn pest (SP) in wheat. Sunn pest causes damage by feeding on wheat berries and injecting a salivary enzyme damaging the gluten. For measurement of SP damage in bulk wheat, NIR calibration models developed for mixtures containing 0–10% and 0–100% sound and SP damaged wheat resulted in R2 of 0.25 and 0.89 and SECVs of 2.75 and 10.9, respectively. The 0–100% model was considered a qualitative measure of damage, but predictions were poor over 0–10% which is a critical range for commercial applications. Discrimination between single kernels of Sound and SP-damaged was typically good, with classification accuracy averaging ∼75% for both visible and NIR although some were poor, which greatly affected the average. Average classification accuracy was ∼85% for spectral data that contained kernels from all samples. While the potential for using visible or NIR spectroscopy was shown, results highlighted the need to develop a more robust SP classification model to further evaluate the single kernel model.