Comparative analysis of starch properties of different root and tuber crops of Sri Lanka

A novel starch from Trichosanthes kirilowii roots: A comparison of its composition, structure and physicochemical properties with conventional root starch

This study investigated the properties of a novel medicinal starch isolated from the roots of Trichosanthes kirilowii (TKRS). The multiscale structural and physicochemical properties of TKRS were characterized and compared with two common starches, sweet potato starch (SPS) and kudzu starch (KS), to elucidate the influence of structural characteristics on the physicochemical properties of these root starches. TKRS granules exhibited elliptical and irregular polygonal shapes, with the largest median particle size (14.48 μm). TKRS had a lower amylose content (15.03 %) and a lower molecular weight (8.40 × 107 g/mol). XRD analysis confirmed a C-type crystallinity pattern, with a higher crystallinity degree (21.51 %) and a high degree of short-range ordered structure. Further analysis of the chain length distribution revealed that TKRS contained a larger proportion of long-chain amylopectin. Compared to SPS and KS, TKRS showed a lower gelatinization temperature (72.65 °C) but a higher peak viscosity (7351 cP). Additionally, despite its relatively lower water retention capacity, TKRS exhibited higher storage modulus and loss modulus than conventional tuber starches. In vitro digestibility analysis indicated that TKRS had a lower rapidly digestible starch content and a higher resistant starch content, highlighting its potential for processing into healthy starch-based food products.

Characterization of the physicochemical properties of Lipu Colocasia esculenta (L.) Schott starch: A potential new food ingredient

The physicochemical properties of Lipu taro starch (LTS), cassava starch (CS) and wheat starch (WS) were analyzed. These starches exhibited a comparable starch content (86 %). However, LTS had a significantly lower amylose content (15.93 %) compared to CS (26.62 %) and WS (33.53 %). Moreover, LTS demonstrated an irregular polygonal cubic morphology with a smaller particle size of 2.55 μm while possessed an A-type crystal structure with high crystallinity at 25.07 %. In contrast, CS and WS had larger particle sizes of 13.33 μm and 16.68 μm, respectively, with lower crystallinities of 22.52 % and 20.33 %. Due to these physicochemical properties, LTS exhibited superior emulsification properties with a higher emulsifying activity index of 8.63 m2/g and an emulsion stability index of 69.18 min, whereas CS and WS had values of 2.35 m2/g and 25.15 min, and 0.37 m2/g and 11.48 min, respectively. LTS also demonstrated enhanced thermal stability, characterized by higher gelatinization temperature (indicated by To, Tp, Tc, and ΔT) and reduced paste viscosity (indicated by PV, TV, FV, SBV, and BDV) compared to CS. However, the mechanical strength of the gel made from LTS (indicated by hardness, adhesiveness, springiness, gumminess, and chewiness) was comparatively inferior to those from CS and WS.

Optimization of starch extraction from Amorphophallus paeoniifolius corms using response surface methodology (RSM) and artificial neural network (ANN) for improving yield with tenable chemical attributes

The development of the extraction process for improving the starch yield from unconventional plants is emerging as a topic of interest. In this respect, the present work aimed to optimize the starch extraction from the corms of elephant foot yam (Amorphophallus paeoniifolius) with the help of response surface methodology (RSM) and artificial neural network (ANN). The RSM model performed better than the ANN in predicting the starch yield with higher precision. In this connection, this study for the first time reports the significant improvement of starch yield from A. paeoniifolius (51.76 g/100 g of the corm dry weight). The extracted starch samples based on yield - high (APHS), medium (APMS), and low (APLS) exhibited a variable granule size (7.17-14.14 μm) along with low ash content, moisture content, protein, and free amino acid indicating purity and desirability. The FTIR analysis also confirmed the chemical composition and purity of the starch samples. Moreover, the XRD analysis showed the prevalence of C-type starch (2θ = 14.303°). Based on other physicochemical, biochemical, functional, and pasting properties, the three starch samples showed more or less similar characteristics thereby indicating the sustentation of beneficial attributes of starch molecules irrespective of the variation in extraction parameters.

Relationship among gelatinization, retrogradation behavior, and impedance characteristics of potato starch

In this study, the physicochemical properties of potato starch from different varieties were investigated. Furthermore, the relationships among gelatinization, retrogradation behavior, and impedance characteristics of potato starch gels were evaluated by texture analysis, low-field nuclear magnetic resonance spectroscopy, and electrical impedance spectroscopy. The results indicated amylose content was positively correlated with setback viscosity, and negatively correlated with T_o and ΔH. In addition, impedance values of potato starch gels differed in a frequency-dependent manner. Notably, higher frequencies resulted in low diffusion of ions in prepared gels, which combined with the concentration of mobile ions in free water, led to a gradual decrease in impedance module. Compared with phase values, impedance module showed high correlation with gelatinization parameters (T_o, T_p, and T_c) and viscosity parameters (peak temperature and setback viscosity), more notably at frequencies below 100 Hz. In this context, the electric current flowed through mobile ions that interacted with bound water attached to the starch molecules at lower voltage frequencies, and were repressed by the formation of an ordered and compact gel network during retrogradation. Collectively, these results indicate that impedance spectroscopy can be potentially used as an efficient and reliable method to predict gelatinization and retrogradation behavior of potato starch.

The combined effect of thermal-acid hydrolysis, periodate oxidation, and iodine species removal on the properties of native tapioca (Manihot esculenta Crantz) starch

Through a four-step top-down approach, native tapioca starch (NTS) was thermally acid-hydrolyzed, periodate-oxidized with subsequent removal of iodine species (i.e., IO₄(-), IO₃(-), I(-), and I₂), and dialdehyde tapioca starch (DTS) alcohol-precipitation. The percent yield was ∼91%. Analyses confirmed the presence of aldehydic functionalities (∼71%), effectual iodine species removal (∼98%), and enhanced water-solubility (∼96.57%). Besides, the combined treatment significantly reduced the M_w (∼57.81 kDa) and ameliorated homogeneity as well as thermal stability (T_max ∼ 667.15 °C). Structural-spectral characterization also confirmed the presence of aldehydic functionality, polymorphic transition (C- to A-type), and a higher degree of crystallinity (∼91.77%), the latter further corroborated by thermal analysis. The morphological study revealed that the combined treatment reduced size (∼393.55-nm-diameter and ∼5.22-μm-length) and changed shape into rod-like crystals. DTS showed considerably and significantly low cytotoxicity to HaCaT cells in vitro at the concentrations assayed over the test period (24 h). DTS's conformation was most stable at -289 kcal/mol and -151.7 au heat formation and minimum potential energies, respectively. Overall, these results demonstrated that the combined treatment had no deleterious effects on NTS's properties, thus yielded DTS with ideal properties for multifarious uses.

Isolation, characterization, modification and uses of taro starch: A review

Taro is a major root crop utilized widely for diverse food and non-food applications. Taro corms are processed into various forms before consumption, which makes them digestible and palatable, extends the shelf life and reduces post-harvest losses. Taro corm contains starch as the major carbohydrate, accounting up to 70-80% of the whole dry matter. The starches obtained from different cultivars and sources significantly differ in physical, chemical, thermal, morphological, and functional properties, which can be explored for varied applications. Starch quality also controls the end-quality of food and industrial products. Several starch modification methods have been studied to improve its positive attributes and to eliminate deficiencies in its native characteristics. These modification methods, which can be categorised into physical, chemical and enzymatic, have proved to improve the characteristics and applications of starch. This review aims to compile the information about the chemical composition, characterization, isolation and modification methods, with an objective of its increased use in food or non-food industries. In addition, challenges and issues in the small-scale processing of taro are discussed. The information available in this review may help in a better understanding and utilization of taro starch.

Characterization of underutilized root starches from eight varieties of ramie (Boehmeria nivea) grown in China

Ramie root is an underutilized starch source. In this study, eight ramie varieties were investigated for starch properties. Starch content ranged from 18.6% to 50.1% in dry root. Starches from different varieties showed similar morphology including ellipsoidal, spherical and truncated granules with size D[4,3] from 10.1 to 14.1 μm. Starch had amylose content from 20.8% to 28.5%. All ramie varieties had B-type starches with relative crystallinity from 24.8% to 27.1%, ordered degree from 0.724 to 0.897 and lamellar thickness from 9.1 to 9.6 nm. Starches had gelatinization peak temperature from 70.5 to 73.8 °C and enthalpy from 14.9 to 15.8 J/g. Starches had swelling power and water solubility from 27.9 to 31.9 g/g and from 11.7% to 15.5%, respectively, at 95 °C, and exhibited different pasting properties with breakdown viscosity from 36 to 377 mPa s and setback viscosities from 1295 to 1863 mPa s. Starch pastes exhibited pseudoplastic behavior and different rheological properties. Native, gelatinized and retrograded starches had resistant starch from 81.7% to 83.9%, from 1.7% to 5.1% and from 5.6% to 13.3%, respectively. The eight varieties were divided into 3 groups according to starch properties. This study is helpful for selecting suitable ramie variety as starch source.

Physicochemical properties of a new starch from ramie (Boehmeria nivea) root

A new starch was isolated from ramie root, and its physicochemical properties were investigated. Ramie dry root contained 45.9% starch. Starch had truncated, ellipsoidal, and spherical granule shapes with size from 7 to 30 μm and D[4,3] about 14.1 μm. Starch contained 38.9% apparent amylose content and 22.4% true amylose content, exhibited B-type crystallinity, and had 26.6% relative crystallinity, 0.82 ordered degree, and 9.2 nm lamellar thickness. Starch had 71.8 °C gelatinization peak temperature and 15.6 J/g gelatinization enthalpy, and exhibited 31.4 g/g swelling power and 17.1% water solubility at 95 °C. Starch had peak, hot, breakdown, final, and setback viscosities at 3048, 2768, 279, 4165, and 1397 mPa s, respectively, and showed peak time at 4.36 min and pasting temperature at 75.0 °C. The native, gelatinized, and retrograded starches contained 15.1%, 94.0%, and 86.5% rapidly digestible starch and 83.3%, 4.0%, and 10.7% resistant starch, respectively. Compared with potato and rice starches, ramie starch was somewhat similar to potato starch but significantly different from rice starch in starch component, crystalline structure, and functional properties. Therefore, ramie starch exhibited the potential to be used as a thickening agent, resistant-digesting food additive, and alternative to potato starch in food and nonfood industries.

Annual committed effective dosage from natural radionuclides by ingestion of local food growing in mineral mining area, Sri Lanka

Sri Lanka's largest mineral sand deposit occurs in Pulmoddai, and the surrounding area of the mineral sand deposit has been identified as a high natural background radiation area. The food crops grown in the area are used for human consumption. However, the long-term consumption of high radioactive foodstuff may cause health defects. The objective of the present study was to assess the radiological impact on individuals due to ingestion of foodstuffs grown in Pulmoddai area. Seasonal food crops growing in the area, including cereals, vegetables, nuts, fruits and yams were collected and used to prepare common meal plans consumed by the residents. Samples were analyzed with high-purity germanium gamma spectrometer for activity concentrations. Activity concentration of ⁴⁰K was observed in higher amounts in every food sample. Trace amounts of ¹³⁷Cs ²³²Th and ⁷Be were also identified. The total committed effective dosage to an adult from gamma-emitting radionuclides from cooked meals was 0.1482 mSv year^-1, and raw foodstuff was 0.0667 mSv year^-1, which are far below than the harmful levels declared by International Atomic Energy Agency. Results concluded that foodstuff and cooked meals consumed by the people who live in Pulmoddai, Sri Lanka, are radiologically safe.

Comparison of physicochemical properties of indigenous Ethiopian tuber crop (Coccinia abyssinica) starch with commercially available potato and wheat starches

In this study the chemical composition, morphology, crystallinity, thermal, and pasting properties of Anchote (Coccinia abyssinica) starch were compared with commercial potato and wheat starches. Anchote starch showed lower total starch content than that of potato starch. Their morphological properties were investigated using scanning electron microscopy. The mean granule width of potato starch was four times greater than anchote starch and two times greater than that of wheat starch. The x-ray powder diffraction analysis revealed that anchote starch had a B-type crystallinity pattern. Differential scanning calorimetric (DSC) results showed the significant differences between the gelatinization temperature of anchote, wheat, and potato starches. The onset, peak, and conclusion temperature of anchote starch were 66.58°C, 70.18°C, and 73.98°C, respectively. The gelatinization temperature of potato and wheat starches were 56.53°C and 55.56°C for onset, 61.46°C and 61.14°C for peak, 68.47°C and 67.06°C for conclusion, respectively. These properties of anchote starch make it an attractive candidate for industrial use.

Nutritional and toxicological composition analysis of selected cassava processed products

Cassava (Manihot esculanta Crantz) is an important food source in tropical countries where it can withstand environmentally stressed conditions. Cassava and its processed products have a high demand in both local and export market of Sri Lanka. MU51 cassava variety is one of the more common varieties and boiling is the main consumption pattern of cassava among Sri Lankans. The less utilization of cassava is due to the presence of cyanide which is a toxic substance. This research was designed to analyse the nutritional composition and toxicological (cyanide) content of Cassava MU51 variety and selected processed products of cassava MU51 (boiled, starch, flour, chips, two chips varieties purchased from market) to identify the effect of processing on cassava MU51 variety. Nutritional composition was analysed by AOAC (2012) methods with modifications and cyanide content was determined following picric acid method of spectrophotometric determination. The Flesh of MU51 variety and different processed products of cassava had an average range of moisture content (3.18 - 61.94%), total fat (0.31 - 23.30%), crude fiber (0.94 - 2.15%), protein (1.67 - 3.71%) and carbohydrates (32.68 - 84.20%) and where they varied significantly in between products and the variety MU51, where no significance difference (p >0.05) observed in between MU51 flesh and processed products' ash content where it ranged (1.02 - 1.91%). However, boiled product and MU51 flesh had more similar results in their nutritional composition where they showed no significant difference at any of the nutrient that was analysed. Thus, there could be no significant effect on the nutrient composition of raw cassava once it boiled. Cyanide content of the MU51 flesh and selected products (boiled, starch, flour and chips prepared using MU51 variety), showed wide variation ranging from 4.68 mg.kg-1 to 33.92 mg.kg-1 in dry basis. But except boiled cassava all processed products had cyanide content <10 mg.kg-1, which is the safe level recommended by the Codex Alimentarius Committee of the FAO/WHO. Thus, preparing products such as flour, starch and chips using MU51 variety could be safe for human consumption. 

Physicochemical properties and micro-structural characteristics in starch from kudzu root as affected by cross-linking

Kudzu starch was cross-linked with sodium trimetaphosphate (STMP) at different temperatures, time and of STMP concentrations in this work. The cross-linked starches (CLSs) were fractionated further into cross-linked amylose and amylopectin in order to compare the effect of cross-linking on the microstructure. According to scanning electron microscope (SEM), CLSs displayed the resemble appearance of spherical and polygonal shapes like NS. X-ray diffraction (XRD) revealed that amylose of native starch (A), NS and CLS displayed a combination of A-type and B-type structure, while that was not found in amylose of cross-linked starch (CLA). The deconvoluted fourier transform infrared (FT-IR) indicated that crystal structure of kudzu starch was losing with the proceeding of cross-linking reaction. The CLSs exhibited a higher retrogradation and freeze-thaw stability than NS. This was accompanied by a significant decrease in sedimentation, transparency, swelling power and solubility.

Comparison of starches from five plants of Sect. Stenophora Uline and Sect. Lasiophyton Uline of Dioscorea grown in China

BACKGROUND

Dioscorea resources with vital medicinal and functional values are abundant in south-west regions of China, especially in Sichuan Province. However, the resource in this region has received less attention compared with that of the north. D. zingiberensis, D. collettii, D. kamoonensis cv. Emei and Jinfo, and D. melanophyma from Sichuan Province and Chongqing City were studied with regard to the most abundant carbohydrate (starch) to search for new medicinal and food resources.

RESULTS

The starches were small round granules or small oval granules and large elongated granules, except D. zingiberensis starch granules, which were disc-like in shape. D. zingiberensis and D. collettii starches showed higher values in total starch content, water-binding capacity and infrared ratio of absorbance bands at 1047/1035 and 1047/1022 cm⁻¹. Differential scanning calorimetry analysis demonstrated a higher gelatinisation temperature required more energy during the gelatinisation process. D. zingiberensis and D. collettii starches showed higher resistant starch content of 724.0 and 693.2 g kg⁻¹, respectively, with lower hydrolysis index and estimation of glycaemic index. All the starches exhibited an A-type pattern except D. melanophyma starch, which showed a C-type pattern evaluated by X-ray diffraction.

CONCLUSION

These results showed that the starches with their low hydrolysis index values possessed potential values as healthy food.

Physicochemical Characterization of Arrowroot Starch (Maranta arundinacea Linn) and Glycerol/Arrowroot Starch Membranes

In the current work, physicochemical properties of arrowroot starch and thermal properties of glycerol/arrowroot starch membranes were investigated. Arrowroot starch exhibited high purity (starch content >99%) with amylose content >40% and granule size dispersion between 29 and 126 μm. Arrowroot starch has a gelatinization temperature of 63.94°C and a B-type crystalline structure. Arrowroot starch, in combination with three levels of glycerol, was used to manufacture membranes by casting method. Increasing the plasticizer effect due to glycerol content increased the water weight loss of the membranes at temperatures higher than 110°C. Additionally, the onset temperature of the endothermic peak observed by differential scanning calorimetry and associated to water removal from the membranes changed with glycerol content. Physicochemical and thermal properties of arrowroot starch and glycerol/arrowroot starch membranes were similar to those reported previously for other starch sources. From the data obtained in this study, it is clear that arrowroot starch could have promising industrial applications.

Chemical and structural properties of sweet potato starch treated with organic and inorganic acid

In the present study sweet potato starch was treated with hydrochloric acid or citric acid at 1 or 5 % concentration and its properties were investigated. Citric acid treatment resulted higher starch yield. Water holding capacity and water absorption index was increased with increased acid concentration. Emulsion properties improved at 5 % acid concentration. The DE value of acid-thinned sweet potato starches was ranged between 1.93 and 3.76 %. Hydrochloric acid treated starches displayed a higher fraction of amylose. X-ray diffraction (XRD) study revealed that all the starches displayed C-type crystalline pattern with varied crystallinity. FT-IR spectra perceived a slight change in percentage intensity of C-H stretch of citric acid modified starches. Starch granules tended to appear less smooth than the native starch granules after acid treatment in Scanning Electron Micrographs (SEM) with granule size ranging between 8.00 and 8.90 μm. A drastic decrease in the pasting profile was noticed in hydrochloric acid (5 %) treated starch. While 5 % citric acid treated starch exhibited higher pasting profile. Differential Scanning Calorimeter (DSC) showed that peak and conclusion gelatinisation temperatures increased with increase in hydrochloric acid or citric acid concentration. Hence citric acid was found to mimic the hydrochloric acid with some variation which suggests that it may have promising scope in acid modification.

Comparative analysis of nutritional quality of five different cultivars of sweet potatoes (Ipomea batatas (L) Lam) in Sri Lanka

Nutritional attributes of flours obtained from five different cultivars of sweet potato roots commonly available in Sri Lanka showed significant differences in the tested parameters. The starch level ranged between 33% and 64% on the dry basis and the extractability from fresh tubers was governed by the quantity of starch. The crude fiber level ranged between 2.1% and 13.6% on dry basis and the highest level was observed in swp7 (CARI 273) and resistant starch ranged from 14.2% to 17.2%. Higher percentage of resistant starch from total starch was found in Wariyapola red (swp1) cultivar resulting in lower digestion level while higher levels of digestion was evident in cultivars with lower levels of resistant starch with high level of total starch. Low levels of calcium and significant levels of iron were found in the five cultivars studied. Crude protein level was in the range of 1.2–3.3% on dry basis and trypsin inhibitor activity level (TIA) was significantly different (P > 0.05) in the cultivars studied while heating resulted in a significantly high reduction in the TIA level than in unheated condition. Polygonal or round shaped starch granules were in the range of 16.8–23.5 μm and low level of starch digestion was shown in cultivars containing larger granules. Total amylose content lies in the range 15.4–19.6% and cultivars having higher percentage of amylose showed higher level of in vitro pancreatic digestion (Pallepola [swp4] and swp7). The starch digestibility of sweet potato flour was in the range of 36–55% and the highest digestion was observed in swp7. Orange fleshed cultivars (swp4 and swp7) were comparatively rich in nutrients and digestibility than the other three studied cultivars.

Effect of nitrogen and sulfur fertilization on accumulation characteristics and physicochemical properties of A- and B-wheat starch

The effects of nitrogen (N) fertilization at the rates of 0 and 230 kg hm(-2) combined with selected sulfur (S) fertilization rates of 0, 46, 56, 77, and 115 kg hm(-2) on A- and B-wheat starch granule accumulation, composition, and thermal and pasting properties were investigated. Scanning electron micrographs revealed that A- and B-starch granules accumulation during grain filling can be influenced significantly by N and S fertilization, and B-granules tend to be more sensitive to S fertilization than A-starch granules. The doses of nitrogen and sulfur fertilization on starch properties were not positively correlated; higher concentration of fertilizers failed to cause a higher effects. N230S46 and N230S56 treatment resulted in the higher peak viscosity, trough viscosity, breakdown viscosity, final and setback viscosity, and gelatinization temperature (To, Tp, Tc) according to differential scanning calorimeter (DSC) and rapid visco analyzer (RVA), respectively.

Physicochemical properties of flours and starches derived from traditional Indonesian tubers and roots

Flours and starches isolated from traditional tubers and roots grown in Indonesia have physical and chemical properties suitable for certain food applications. Compared to other flour samples, cassava and canna flours contained the highest amount of total starch (TS) (77.4 and 77.1 %, respectively). Taro starch had the lowest amount of TS among other starch samples with 75.4 %. The highest amount of amylose was observed from yam and canna flours (25.2 and 23.2 %, respectively). Among starch samples, canna starch contained the highest amylose content (30.4 %), while taro had the lowest (7.6 %). In terms of protein content, arrowroot flour had the highest amount (7.7 %), in contrast to cassava flour which had the lowest (1.5 %). Compared to other flours, canna and konjac flour were the most slowly digested which indicated by their high amount of resistant starch (RS). Canna starch had the highest swelling power and viscosity than other starches and flours. The clearest paste was observed from cassava flour and starch as opposed to konjac starch which was the most opaque paste.

Starch determination, amylose content and susceptibility to in vitro amylolysis in flours from the roots of 25 cassava varieties

BACKGROUND

Cassava cultivars are classified following different criteria, such as cyanogenic glucoside content or starch content. Here, flours from the roots of 25 cassava varieties cultivated simultaneously in a single plantation, were characterized in terms of starch content (SC), amylose content (AC), α-amylolysis index (AI) and gel formation ability. Resistant starch content (RS) was measured in 10 of the samples.

RESULTS

Cassava flours exhibited high SC, low AC and low AI values, with differences among varieties. Cluster analysis based on these parameters divided the cultivars in four groups differing mainly in SC and AC. AI and AC were inversely correlated (r = -0.59, P < 0.05) in 18 of the cultivars, suggesting AC as an important factor governing the susceptibility to enzymatic hydrolysis of starch in raw cassava. Differences in susceptibility to amylolysis, assessed by RS, were also recorded in the sample subset analyzed. Most flours yielded pastes or gels upon heating and cooling. Gels differed in their subjective grade of firmness, but none exhibited syneresis, confirming the low retrogradation proclivity of cassava starch.

CONCLUSION

Some differences were found among cassava samples, which may be ascribed to inter-cultivar variation. This information may have application in further agronomic studies or for developing industrial uses for this crop.