Effects of mucilage on the thermal and pasting properties of yam, taro, and sweet potato starches

This study investigates the effects of water-soluble mucilages (0, 2.5, and 5 g/100 g; w/w, dry basis) on the thermal and pasting properties of isolated starches from three root and tuber crops. The results show that yam tuber presents the greatest level of mucilage and also possess the largest amylose content of the three isolated starches. The addition of mucilage caused a remarkable increase in the temperature of gelatinization for the three tested starches due to the competition for water during starch gelatinization. Furthermore, adding mucilage increased the phase transition temperature range (Tc-To) of starches but decreased enthalpy (ΔH). However, although the pasting temperature increased with the addition of mucilage into tuber starches, it did not change that of taro starch. The peak viscosity of taro and sweet potato starches decreased significantly as their mucilages were added into each starch suspension system (p < 0.05). However, the addition of mucilage slightly increased the viscosity of yam starch. Furthermore, the addition of mucilage slightly increased the swelling power of yam and taro starches, but did not change that of sweet potato starch.     

Preparation of microcapsules containing antimicrobial lipopeptide from Bacillus amyloliquefaciens ES-2 by spray drying

Using a fermentation broth produced by Bacillus amyloliquefaciens ES-2 as a raw material, a preparation method for antimicrobial lipopeptide powders was developed. Antimicrobial lipopeptide microcapsules were obtained by a spray-drying process using maltodextrin and porous starch as composite wall materials. Optimal encapsulation conditions comprised a ratio of wall materials to the core material of 5%, a ratio of porous starch to maltodextrin of 1/9, a drying air flow of 70 m³/h and an inlet gas temperature of 220 °C, producing a high yield of microcapsules of 63.9 ± 0.5%. The lipopeptides retained their desired bioactivity and had a spherical form after spray drying, with an antimicrobial potency of 25711.3 ± 34.5 IU/g evaluated by the cylinder-plate method, and their preservation percent was about 81.5%. Because of its low cost, high efficiency, simplicity and easy of scale-up, the technology is expected to be efficient for producing antimicrobial lipopeptide powders and to be helpful in the application of antimicrobial lipopeptides as food additives.     

On the formation of uniform alginate-silica microcomposites with ordered hierarchical structures

The hierarchical ordering at micro- and nano-scales in hybrid composites of alginate and silica nanoparticles was observed when uniform microparticles were formed in a single step via a micro-fluidic jet spray drying. A polymer-mediated ‘bricks and mortar’ strategy initially aligned silica nanoparticles into nano-clusters in the dispersion with sizes depending on the ratio of polymer to silica. Evaporation induced self-assembly during spray drying then formed uniform microparticles with shells enriched with silica nanoparticles, enclosing arrays of close-packed spherical aggregates of these nano-clusters. The final structures of particles were determined by the drying temperature and the ratio of alginate to silica, indicating that this approach could be used to fabricate diverse structural motifs. The combination of polymer-mediated self-assembly with a moderate temperature spray drying could be a versatile route to synthesize thermal sensitive, ordered biomaterials for food and pharmaceutical-related applications.     

Preparation and Characterization of Annealed‐Enzymatically Hydrolyzed Tapioca Starch and the Utilization in Tableting

Tapioca starch was annealed at 60°C for 90 min followed by hydrolysis with α‐amylase at 60°C at various lengths of time (30, 60 and 120 min) to obtain high‐crystalline starches. The reaction products were subjected to spray drying to obtain annealed–enzymatically hydrolyzed–spray dried tapioca starch (SANET) in the form of spherical agglomerated granules. The properties of SANET were compared with those of annealed–spray dried tapioca starch without enzymatic treatment (SANT) and native–spray dried tapioca starch (SNT). Scanning electron micrographs of the starch samples were used to study the morphological changes and to suggest the mode of enzyme attack during hydrolysis. The á‐amylase preferentially attacked the interior of the starch granules, leaving a deep round hole on the starch granule surface. It was found by X‐ray diffraction that both annealing and amylolysis did not alter the A type diffraction pattern. The% relative crystallinity of SANET was raised with increasing hydrolysis time and with decreasing amylose content. High performance size exclusion chromatography (HPSEC) demonstrated the decrease of the degree of polymerization (DP) of the amylose fraction of SANET after prolonged hydrolysis. For the utilization of SANET as tablet filler, it was directly compressed by a tablet compression machine at 4 kN to obtain tablets. The increased relative crystallinity of starch resulted in increased crushing strength and disintegration time, but in a decreased tablet friability.     

不同芋头品种真空微波干燥品质变化的比较

分析8个不同芋头品种真空微波干燥前后营养成分的变化,比较不同芋头品种生产的芋头脆片色泽、硬度、脆度、膨化率、微观结构和感官品质等品质变化。结果表明:新鲜芋头含水量高达61.33~82.94%,奉化芋头含量最高;淀粉含量范围为15.87~30.25%,香沙芋含量最高;荔浦芋中的蔗糖最高,约为2.6 g/100 g,红香芋中的可溶性蛋白为1455 mg/100 g,明显高于其他品种。芋头片干燥后营养成分中除了蔗糖,其他含量均减少,且减少量差异显著,淀粉含量减少最多。不同品种的芋头真空微波干燥后品质差异明显,其中,荔浦芋、龙香芋、奉化芋头、槟榔芋和香沙芋亮度大、色差小,产品色泽保持良好;龙香芋和乌骨芋外形膨化且内部多孔状结构明显,硬度适中、酥脆性好;龙香芋、奉化芋头和乌骨芋的色泽、形态、口感、风味综合评分高,可接受程度明显高于其他芋头品种。     

不同干燥工艺对香蕉抗性淀粉的影响

本研究以绿色香蕉为原料,以香蕉抗性淀粉保留率、碘吸收曲线、颗粒形貌以及抗性淀粉的结晶结构、吸水指数、水溶性指数、L 值为衡量指标,系统分析和比较了各干燥技术(热风干燥、挤压干燥、真空冷冻干燥和喷雾干燥)对绿色香蕉功能因子--抗性淀粉的保留效果以及产品品质和特性的影响。结果表明：真空冷冻干燥、低温热风干燥(50℃)和喷雾干燥对香蕉抗性淀粉及其颗粒结构的保留效果以及产品品质均优于100℃热风干燥,而挤压干燥对香蕉抗性淀粉及颗粒结构的破坏效果最明显,产品色泽也最深。     

Isolation and partial characterization of Mexican taro (Colocasia esculenta L.) starch

Taro starch was isolated from Mexican variety and its morphological, physicochemical, and molecular characteristics were evaluated. Yield starch (in dry basis) was 81%, and this starch had low AM content (2.5%). Taro starch granules showed a mixture of shapes with sizes between 1 and 5 µm. Taro starch presented an A‐type XRD pattern with a crystallinity level of 38.26%. Solubility and water retention capacity did not change in the temperature range of 50–70°C and thereafter they increased as temperature increased too. Taro starch showed high peak viscosity due to its high AP content. The peak temperature of gelatinization of taro starch was 80.6°C with an enthalpy value of 10.6 J/g, with low retrogradation rate due to its low AM content. Weight‐average molar mass (Mw) and gyration radius (Rz) of taro starch were 1.21 ± 0.8 × 10⁹ g/mol and 424 ± 70 nm, respectively. Taro tuber could be an alternative for starch isolation with functional and physicochemical characteristics for food and non‐food applications.     

Development of extruded snacks using taro (Colocasia esculenta) and nixtamalized maize (Zea mays) flour blends

Extruded snacks were prepared from flour blends made with taro and nixtamalized (TF-NMF) or non-nixtamalized maize (TF-MF) using a single-screw extruder. A central composite design was used to investigate the effects of taro flour proportion in formulations (0-100 g/100 g) and extrusion temperatures (140-180 °C) on the following indices: expansion (EI), water solubility (WSI), water absorption (WAI) and fat absorption (FAI). Moreover, selected TF-NMF and TF-MF extruded products were partially characterized through proximate chemical analysis, resistant starch, color, pH, water activity, apparent density, hardness, and sensory analysis. Results indicated that EI and WSI of both TF-MF and TF-NMF extrudates were significantly increased by the use of higher proportions of taro flour, while the opposite behavior was observed for the FAI (p < 0.05). Taro flour at higher proportions in both extrudates did not produce a significant change of WAI, while the use of higher extrusion temperatures only caused a significant increase of FAI in TF-MF extrudates (p < 0.05). This study showed that flour mixtures made from taro and nixtamalized maize flour produced puffed extruded snacks with good consumer acceptance.     

The loss of OSA‐modified starch emulsifier property during the high‐pressure homogeniser and encapsulation of multi‐flavour bergamot oil by spray drying

The encapsulation of bergamot oil by spray drying was investigated by using octenyl succinylated waxy maize starch as wall material and bergamot oil as core. The bergamot oil is majorly composed of d‐limonene, linalool and linalyl acetate. High‐speed and high‐pressure homogenisers were used as major tools of emulsification process. The results indicated that some chemical functional groups were lost during the high‐pressure homogenisation. Moreover, larger emulsion droplet size (5–10 μm) was observed when emulsion passed through high‐pressure homogeniser. Meanwhile, the saturation of carrier solution before preparing the emulsion was also important to produce the encapsulated flavour powder by spray drying. The optimal value of air inlet temperature at 160 °C to give the highest flavour retention and the lowest surface oil content was observed. Furthermore, the retention of linalool after spray drying was higher than 100%. The transformation of each flavour might occur.     

Physicochemical properties and in vitro digestibility of flours and starches from taro cultivated in different regions of Thailand

This research aimed to study physicochemical properties and in vitro digestibility of flours and starches from taro cultivated in different regions of Thailand, that is, Kanchanaburi (KB), Chiang Mai (CM), Phetchaburi (PB) and Saraburi (SB). Taro starches were extracted from taro flours using either water or alkaline extraction. The taro flours had significantly (P ≤ 0.05) larger particle size, higher pasting and gelatinisation temperatures, and resistant starch content but lower total starch content, whiteness (L* value), paste viscosities and clarity than their corresponding extracted starches. All the taro starches exhibited polygonal and irregular granules and gave A-type X-ray diffraction pattern. The alkaline-extracted taro starches had significantly (P ≤ 0.05) higher extraction yield, total starch content, L* value, pasting and gelatinisation temperatures, and paste clarity but lower granular size, amylose content, resistant starch content, paste viscosities and relative crystallinity than their water-extracted counterparts.     

Physical and chemical properties of ultrasonically, spray-dried green banana (Musa cavendish) starch

Ultrasonic wave propagation and the spray dryer technique were applied to study their effect on the physical and chemical properties of green banana starch. The results showed high resistant starch content, which was reduced by ultrasound treatment and also by spray drying. Both techniques increased the solubility, swelling power and water absorption capacity. The gels exhibited non-Newtonian shear-thinning behavior, since flow behavior index was less than one (n < 1). Ultrasound wave propagation reduced yield stress and consistency coefficient in starch gels. Under oscillatory shear, all gels exhibited solid-like viscoelastic behavior, storage modulus was higher than loss modulus to entire frequency range (G′ > G′′), which was confirmed by the Cox-Merz experiment that showed that the complex dynamic viscosity was greater than the apparent viscosity in all samples. The gelatinization temperature was mainly influenced by drying technique and ultrasound treatment reduced the amount of energy required to gelatinize the starch.     

芋头淀粉纳米颗粒的制备及其表征

以芋头淀粉为原料,经普鲁兰酶脱支不同时间,在4 ℃下回生制备淀粉纳米颗粒,通过Zeta电位仪、傅里叶红外光谱仪、差示扫描量热仪和X射线衍射仪、扫描电子显微镜等对芋头原淀粉和淀粉纳米颗粒的结构和形貌进行了表征。结果表明,经过不同酶解时间(4、6、8和10 h)回生得到的芋头淀粉纳米颗粒的平均粒径分别为354.7、235.4、274.6和400.9 nm。傅里叶红外光谱显示芋头淀粉纳米颗粒没有出现新的特征峰,但分子间作用力和氢键作用都有所增强。与芋头原淀粉比较,淀粉纳米颗粒的糊化温度和焓值降低,糊化温度范围增大,晶型由A型变为V型,相对结晶度明显降低。芋头淀粉纳米颗粒呈多边形或球形,比表面积增大,出现了一定的团聚现象。     

Improving the emulsifying property of potato protein by hydrolysis: an application as encapsulating agent with maltodextrin

Potato protein concentrate (PPC) is a by-product from starch industry and traditionally used as a low-value ingredient. Depending on its recovery/drying methods, protein functionality and technological applications can be compromised. Hydrolysis offers an alternative to this challenge by modifying protein structure, opening a prospect to find value-added opportunities for this residue. Hence, this study aimed to evaluate the impact of enzymatic hydrolysis on the emulsifying property of PPC. More importantly, we investigated the application of PPC with maltodextrin (proportion of 30:70) as wall material in the microencapsulation of a lipophilic ingredient by spray drying. When PPC was submitted to a 2% degree of hydrolysis, its emulsifying capacity significantly increased from 359 to 416 g oil/g protein. Spray drying microencapsulation using potato protein concentrate/hydrolysate and maltodextrin as wall materials were effective in entrapping flaxseed oil. Additionally, high encapsulation efficiency was observed (92– 96%). Overall, the application of potato protein combined with maltodextrin as wall material was successful for spray drying microencapsulation.     

Optimisation of a pilot‐scale spray drying process for probiotic yoghurt,using response surface methodology

The influence of drying air temperatures, drying air flow rate and feed flow rate on percentage survival rate (% SR) of starter and probiotic bacteria, moisture content, water activity and colour of probiotic yoghurt powder produced using a pilot‐scale spray dryer was investigated. Optimisation of spray drying conditions was achieved based on the desirability value. Results showed that inlet air temperature, drying air flow rate, feed flow rate and outlet air temperature of 150 °C, 478 m³/h, 2 L/h and 63.3 °C, respectively, were optimal conditions to produce powder that meets quality specifications and with a satisfactory% SR.     

Physicochemical properties and storage stability of spray‐dried soya bean sprout extract

Amylase is a very important enzyme due to its wide food applications. To preserve amylase activity in soya bean sprout extract (SSE), SSEs were spray‐dried with 10% maltodextrin and 0–3% alginic acids, and their physicochemical properties and storage stability were compared with freeze‐dried one. SSE exhibited maximum amylase activity at pH 7.0 and 60 °C, with the most active substrate specificity towards soluble starch. Spray‐dried SSEs exhibited higher water solubility index (WSI) and in vitro relative amylase activity but lower water vapour sorption (WVS) and smaller particle size than freeze‐dried SSE. For spray‐dried SSEs, particle size, WSI and in vitro relative amylase activity increased while WVS decreased with increasing % alginic acid. This study demonstrated that spray drying of SSE, especially with 10% maltodextrin and 2% alginic acid, was effective in keeping amylase active and stable during 7‐week storage at room temperature (25 °C).     

An investigation into lactose crystallization under high temperature conditions during spray drying

Lactose crystallization was studied at high temperature conditions in a Buchi B-290 mini spray dryer. The inlet gas temperature was 200 °C, and an insulating material was used to reduce the heat loss from the drying chamber (outlet temperature 157 °C), thus increasing the gas and particle temperatures. At these conditions, lactose crystallinity was found to increase significantly compared with a case where it was spray dried at 170 °C in a non-insulated drying chamber (outlet temperature 90 °C), but the process yield was lower for the former case (0.16% yield) than for the low temperature conditions (47% yield). There is some evidence that high-temperature spray drying of lactose is more likely to give more β-lactose anomer. Different analytical techniques (Fourier Transform Infrared Spectroscopy, modulated differential scanning calorimetry, moisture sorption test, Raman spectroscopy) were used to investigate the degree of crystallization and possible lactose anomer formation during this spray drying at high inlet gas temperatures.     

Microencapsulation using starch as wall material: A review

Microencapsulation is a process oriented to protect substances that are susceptible to decomposition or reduction in their functionality due to different degradation reactions (i.e., oxidation, hydrolysis, etc.). Diverse wall materials, including some carbohydrates, preserve substances against adverse temperature, pH, humidity, oxygen, and other components that can react with the protected material. Starch is a wall material that is widely used for microencapsulation purpose. Unmodified and modified starches are increasingly considered for microencapsulation of vitamins, essential oils, flavors, drugs, and microorganisms. Recently, spherical aggregates of starch using small granules (1–3 μm) were developed for encapsulation purposes. Spherical aggregates are produced when small starch granules in the presence of additional bonding agents (e.g., proteins and hydrocolloids) are spray dried. Some studies have reported the application of spherical aggregates, but they neither report the effects of amylose content nor the molecular weight of amylopectin. In this sense, this review focuses on the state of the art of starch spherical aggregates and the perspectives of their applications as encapsulating agents.     

Production of a red–purple food colorant from Opuntia stricta fruits by spray drying and its application in food model systems

Opuntia stricta fruit juice is a potential source of betacyanin pigments which can be used as a natural red-purple food colorant. In this work a powder food colorant was obtained by co-current spray drying of O. stricta fruit juices with a bench-scale two fluid nozzle spray dryer. Glucose syrup (DE 29) was used as drying aid. Optimum conditions for spray drying were as follow: juice content (20% v/v; 1.2 °Brix), glucose syrup content (10% w/v), liquid feed rate (0.72 l/h), spray air flow-rate (0.47 m³/h), drying air flow-rate (36 m³/h), and inlet drying air temperature 160 °C. Color was retained during the drying process (>98%) and drying yield was high (58%). The powder colorant showed high color strength (4.0), being this color strength stable when stored at room temperature for one month. This colorant was successfully applied in two food model systems: a yogurt and a soft-drink. Food presented a vivid red-purple tonality very attractive for consumers that was maintained after one month under refrigeration (4 °C) (ΔE < 5).     

Effect of Cross-Section Differences and Drying Temperature on the Physicochemical, Functional and Antioxidant Properties of Giant Taro Flour

Giant swamp taro, Cyrtosperma merkusii, consumed and regarded as indigenous food in many regions of Cameroon, is a potential bio-source of antioxidants as well as flours for use in different food formulations but which has not been widely studied. The present study was carried out to determine the effect of drying conditions on the chemical composition as well as the physical and functional properties and antioxidant activity of flours of this tuber. Slices of the yellow and mixed sections of the tubers were processed into flours by sun-drying (temperature ≈35 °C) and hot air electric drying at varying temperatures (50 °C, 60 °C, and 70 °C) before milling. Drying temperature and technique showed marginal effect on the protein, fat, fiber, ash, and carbohydrate content of taro flours. Color attributes, physical and functional properties, 1,1-diphenyl-2-picryl-hydrazyl radical antioxidant activity, as well as reducing power of flours were found to vary significantly (P?<?0.05) due to either the drying temperature or method. Hot air electric drying at lower temperatures (<70 °C) produced flour with higher water absorption capacity (WAC), water solubility index (WSI), porosity, bulk density, and preserved antioxidant activity of flour, whereas sun-drying was associated with flours of higher WSI but lower WAC, and lower antioxidant capacity. It was noticed that carotenoids and ascorbic acid contributed to the antioxidant activity in taro flours, and taro flours made of different taro portions showed different antioxidant mechanisms. This study highlights the low temperature hot air-drying method as a very good lead for preparation of effective natural functional flours for culinary system.     

Physicochemical Properties of Pin Oak (Quercus palustris Muenchh.) Acorn Starch

Physicochemical properties of acorn (Quercus palustris) starch were studied. Acorn starch granules were spherical or ovoid, with diameters ranging from 3–17 μm. Acorn starch exhibited A‐type X‐ray diffraction pattern, an apparent amylose content of 43.4% and absolute amylose content of 31.4%. Relative to other A‐type starches, acorn amylopectin had a comparable weight‐average molar mass (3.9×10⁸ g/mol), gyration radius (288 nm) and density (16.3 g mol⁻¹nm⁻³). Average amylopectin branch chain‐length corresponded to DP 25.5. Onset gelatinization temperature was 65.0°C and peak gelatinization temperature was considerably higher (73.7°C). The enthalpy change of gelatinization was very high compared to non‐mutant starches (20.8 J/g). An amylose‐lipid thermal transition was not observed. Starch retrograded for 7 d at 4°C had very high peak melting temperature (54.2°C) relative to other A‐type starches. Final (260 RVU) and setback (138 RVU) viscosity of an 8% acorn starch paste was high relative to other starches and pasting temperature was 71.5°C.