Starch from Alberta potatoes: wet-isolation and some physicochemical properties

Effects of synergistic action on rheological and thermal properties of potato starch complexes co-gelatinized with caffeic acid and squash polysaccharides extracted with water and subcritical water

In order to broaden the application range of squash polysaccharide (WESP/SWESP) and caffeic acid (CAA) and improve the quality of potato starch (PS) products, the effects of WESP/SWESP and CAA on the gelatinization, rheology, thermodynamics, microstructure and in vitro digestion of PS were investigated. Meanwhile, the synergistic effect of WESP/SWESP and CAA on PS was further analyzed. Differently, due to WESP and SWESP had different monosaccharide composition and structure, they had different effects on the system. Pasting properties results showed that the presence of WESP/SWESP and CAA significantly reduced the peak viscosity, trough viscosity, breakdown viscosity and final viscosity of PS, especially under the combined action. In rheological tests, all sample gels belonged to the pseudoplastic fluids and weak gel system (tan δ < 1). Besides, thermodynamic properties revealed that WESP/SWESP and CAA synergistic effect had better retrogradation delay effect. In the ternary system, WESP/SWESP, CAA and PS can form a new network structure and improve the stability of the gel system. In addition, the results of infrared spectroscopy, Raman spectroscopy, x-ray diffraction and scanning electron microscopy exhibited that the ternary system can promote the accumulation and winding of the spiral structure of PS chain, and make the structure of PS gel network more orderly and stable. Furthermore, compared with PS gel, the ternary system had lower RDS and higher SDS and RS content, suggesting that the addition of WESP/SWESP and CAA at the same time was more conducive to reducing the hydrolysis rate of PS. This work revealed the interaction between WESP/SWESP, CAA and PS, which improved the physicochemical and digestive properties of PS. It will provide a theoretical basis for improving the quality of potato starch-related products and developing functional foods.

Effects of zucchini polysaccharide on pasting, rheology, structural properties and in vitro digestibility of potato starch

Zucchini polysaccharide (ZP) has a unique molecular structure and a variety of biological activities. This study aimed to evaluate the effects of ZP (1, 2, 3, 4 and 5 %, w/w) on the properties of potato starch (PS), including pasting, rheological, thermodynamic, freeze-thaw stability, micro-structure, and in vitro digestibility of the ZP-PS binary system. The results showed that the appearance of ZP significantly reduced the peak, breakdown, final and setback viscosity and prolonged the pasting temperature of PS, whereas increased the trough viscosity. The tests of rheological showed that ZP had a damaging effect on PS gels. Meanwhile, the results of thermodynamic and Fourier transform infrared exhibited that the presence of ZP significantly retarded the retrogradation of PS, especially at a higher levels. The observation of the microstructure exhibited that ZP significantly altered the microscopic network structure of the PS gels, and ZP reduced the formation of the gel structure. Besides, ZP postponed the retrogradation process of PS gels. Moreover, ZP weakened the freeze-thaw stability of the PS gel. Furthermore, ZP also can decrease the digestibility and estimated glycemic index (eGI) value of PS from 86.04 % and 70.89 to 77.67 % and 65.22, respectively. Simultaneously, the addition of ZP reduced the rapidly digestible starch content (from 25.09 % to 16.59 %) and increased the slowly digestible starch (from 24.99 % to 26.77 %) and resistant starch content (from 49.92 % to 56.64 %). These results have certain guiding significance for the application of ZP in starch functional food.

Biomacromolecule assembly of soy glycinin-potato starch complexes: Focus on structure, function, and applications

The effect of the cross-linking mechanism and functional properties of soy glycinin (11S)-potato starch (PS) complexes was investigated in this study. The results showed that the binding effecting and spatial network structure of 11S-PS complexes via heated-induced cross-linking were adjusted by biopolymer ratios. In particular, 11S-PS complexes with the biopolymer ratios of 2:15, had a strongest intermolecular interaction through hydrogen bonds and hydrophobic force. Moreover, 11S-PS complexes at the biopolymer ratios of 2:15 exhibited a finer three-dimensional network structure, which was used as film-forming solution to enhance the barrier performance and mitigate the exposure to the environment. In addition, the 11S-PS complexes coating was effective in moderating the loss of nutrients, thereby extending their storage life in truss tomato preservation experiments. This study provides helpful to insights into the cross-linking mechanism of the 11S-PS complexes and the potential application of food-grade biopolymer composite coatings in food preservation.

Effect of infection of potato plants by Potato virus Y (PVY), Potato virus S (PVS), and Potato virus M (PVM) on content and physicochemical properties of tuber starch

Potato virus Y (PVY), Potato virus S (PVS), and Potato virus M (PVM) infection of potato plants leads to decreased dry matter and starch content in tubers. Starch samples from potato tubers infected with PVY, PVS, and PVM had higher amylose content. Granules of starch isolated from potato tubers infected by PVS exhibit larger granules than starch granules isolated from tubers of healthy plants. In contrast, in the case of PVM and PVY infection, starch granules were significantly smaller in diameter. A decrease in the degree of crystallinity has been observed in all samples of starches obtained from the tubers of infected plants compared to starch isolated from tubers of healthy plants. A slight decrease in gelatinization temperature was noted for starch samples isolated from tubers infected by PVY and PVM, and a slight increase in gelatinization temperature for starch samples isolated from tubers infected by PVS compared to starch isolated from tubers of healthy plants. In all samples of starch obtained from tubers of infected plants, an increase in the value of gelatinization enthalpy was observed. Thus, it can be concluded that damage to potato plants by PVM and PVY leads to a significant decrease in the quality of starch in tubers. At the same time, infection by PVS had practically no considerable effect.

Effect of Potato Starch Hydrogel:Glycerol Monostearate Oleogel Ratio on the Physico-Rheological Properties of Bigels

Bigel (BG) has been shown to be promising for the food industry due to the possibility to manipulate the properties of the system by adjusting the ratio of each individual phase, namely the hydrogel (H) and oleogel (O) phases. This work aimed to evaluate the influence of the O:H ratio on the physical-rheological properties of BG produced with potato starch (PS) and glycerol monostearate (GM). The hydrogel hardness (i.e., 1423.47 g) directly influenced the viscosity of the BG samples, as BG with a higher H-phase presented the highest viscosity and firmness. All BG samples presented shear-thinning behavior and structural breakdown at ~50 °C. BG with a higher O-phase had superior results for thermal stability, softer texture, and yield stress values, representative of good plasticity and spreadability, as compared to BG with less O-phase. The BG with 80% H-phase was less stable during the 21 days of storage in relation to the other BG samples. This study showed the role that the O:H ratio plays in the development of PS-GM-based BGs with tailor-made physical-rheological properties. In addition, the BG is an easily reproduced system with great potential to be used as a trans and saturated fat substitute in food applications.

Plant Cover Stimulates Quicker Dry Matter Accumulation in “Early” Potato Cultivars without Affecting Nutritional or Sensory Quality

“Early” potato crops are grown in the Mediterranean basin and are marketed from March to June, well before main-crop potato in the spring–summer growth period. Different growing technologies have been implemented to enhance potato “earliness” to achieve a better market price, but at the same time, the applied technologies may influence yield and quality of the ‘early potato’. The main goal of this study was to investigate differences in “early” potato nutritional and sensory characteristics after oil-frying influenced by location and plant covering in five potato cultivars. The present investigation was carried out at two planting locations during two seasons. The application of a plant cover significantly increased the potato tubers’ dry matter, starch, and sugar content in the second season. Sensory analysis of the oil-fried “early” potatoes revealed no differences between potatoes grown with or without the plant cover. We also observed significantly higher dry matter content in potatoes grown at the Split location in the second year, while no differences in the sensory scores between oil-fried potatoes grown at the investigated locations were observed. By employing a plant cover or by choosing a warmer planting location the desired potato maturity level could be reached in less time, and one could more effectively exploit the “early” potato market. By employing such techniques there should be no loss in yield, nutritional or sensory quality of potato tubers.

The Influence of Hydroponic Potato Plant Cultivation on Selected Properties of Starch Isolated from Its Tubers

Starch is a natural polysaccharide for which the technological quality depends on the genetic basis of the plant and the environmental conditions of the cultivation. Growing plants under cover without soil has many advantages for controlling the above-mentioned conditions. The present research focuses on determining the effect of under cover hydroponic potato cultivation on the physicochemical properties of accumulated potato starch (PS). The plants were grown in the hydroponic system, with (greenhouse, GH) and without recirculation nutrient solution (foil tunnel, FT). The reference sample was PS isolated from plants grown in a tunnel in containers filled with mineral soil (SO). The influence of the cultivation method on the elemental composition of the starch molecules was noted. The cultivation method also influenced the protein and amylose content of the PS. Considering the chromatic parameters, PS-GH and PS-FT were brighter and whiter, with a tinge of blue, than PS-SO. PS-SO was also characterized by the largest average diameters of granules, while PS-GH had the lowest crystallinity. PS-SO showed a better resistance to the combined action of elevated temperature and shear force. There was a slight variation in the gelatinization temperature values. Additionally, significant differences for enthalpy and the retrogradation ratio were observed. The cultivation method did not influence the glass transition and melting.

Improving the Biocontrol Potential of Endophytic Bacteria Bacillus subtilis with Salicylic Acid against Phytophthora infestans-Caused Postharvest Potato Tuber Late Blight and Impact on Stored Tubers Quality

Potato (Solanum tuberosum L.) tubers are a highly important food crop in many countries due to their nutritional value and health-promoting properties. Postharvest disease caused by Phytophthora infestans leads to the significant decay of stored potatoes. The main objective of this study was to evaluate the effects of the endophytic bacteria, Bacillus subtilis (strain 10–4), or its combination with salicylic acid (SA), on some resistance and quality traits of stored Ph. infestans-infected potato tubers. The experiments were conducted using hydroponically grown potato mini-tubers, infected prior to storage with Ph. infestans, and then coated with B. subtilis, alone and in combination with SA, which were then stored for six months. The results revealed that infection with Ph. infestans significantly increased tuber late blight incidence (up to 90–100%) and oxidative and osmotic damage (i.e., malondialdehyde and proline) in tubers. These phenomena were accompanied by a decrease in starch, reducing sugars (RS), and total dry matter (TDM) contents and an increase in amylase (AMY) activity. Moreover, total glycoalkaloids (GA) (α-solanine, α-chaconine) notably increased in infected tubers, exceeding (by 1.6 times) permissible safe levels (200 mg/kg FW). Treatments with B. subtilis or its combination with SA decreased Ph. infestans-activated tuber late blight incidence (by 30–40%) and reduced oxidative and osmotic damages (i.e., malondialdehyde and proline) and AMY activity in stored, infected tubers. Additionally, these treatments decreased pathogen-activated GA accumulation and increased ascorbic acid in stored tubers. Thus, the results indicated that endophytic bacteria B. subtilis, individually, and especially in combination with SA, have the potential to increase potato postharvest resistance to late blight and improve tuber quality in long-term storage.

Starch granule size: Does it matter?

Nature has developed starch granules varying in size from less than 1 μm to more than 100 μm. The granule size is an important factor affecting the functional properties and the applicability of starch for food and non-food applications. Within the same botanical species, the range of starch granule size can be up to sevenfold. This review critically evaluated the biological and environmental factors affecting the size of starch granules, the methods for the separation of starch granules and the measurement of size distribution. Further, the structure at different length scales and properties of starch-based on the granule size is elucidated by specifying the typical applications of granules with varying sizes. An amylopectin cluster model showing the arrangement of amylopectin from inside toward the granule surface is proposed with the hypothesis that the steric hindrance for the growth of lamellar structure may limit the size of starch granules.

Characterization of starches obtained from several native potato varieties grown in Cusco (Peru)

Ten native potato varieties grown in Cusco (at 3,672 m above sea level) were used for starches extraction (at a pilot scale), and their physicochemical, functional, morphological, and structural characteristics were assessed. The content of protein, apparent amylose and phosphorus ranged from 0.1% to 0.44%, 23.42% to 35.5%, and 0.07 to 0.10%, respectively. Starch granules revealed smooth surface, with ellipsoidal and spherical shapes, particle size analysis exhibited bimodal or multimodal distribution, while the averaged crystallinity was 27.7% assessed by XRD. Gelatinization temperatures of the starches ranged from 57.4 to 60.1 °C, 60.8 to 64.3 °C, and 68.4 to 71.1°C for To, Tp, and Tc, respectively; and the gelatinization enthalpies ranged from 15.4 to 17.1 J/g. Respect to pasting properties, the peak viscosity and setback viscosity ranged from 12,970 to 16,970 mPa⋅s and from 968 to 2498 mPa⋅s, respectively. Thermogravimetric analysis (TGA) revealed no significant relationship between apparent amylose content and thermal stability. Therefore, the results reveal subtle differences in the functional characteristics of the starches from the native varieties of potato studied, which can be recommended for food industry applications. PRACTICAL APPLICATION: This study contributes to show several varieties of native potatoes from Cusco and their valorization as nonconventional starch source. Describing the physicochemical, functional, and structural characteristics of these starches could be useful for food industry applications.

Tailoring the surface properties and flexibility of starch-based films using oil and waxes recovered from potato chips byproducts

Agrofood byproducts may be exploited as a source of biomolecules suitable for developing bioplastic materials. In this work, the feasibility of using starch, oil, and waxes recovered from potato chips byproducts for films production was studied. The recovered potato starch-rich fraction (RPS) contained an amylopectin/amylose ratio of 2.3, gelatinization temperatures varying from 59 to 71 °C, and a gelatinization enthalpy of 12.5 J/g, similarly to a commercial potato starch (CPS). Despite of its spherical and oval granules identical to CPS, RPS had a more amorphous structure and gave rise to low viscous suspensions, contradicting the typical B-type polymorph crystal structure and sluggish dispersions of CPS, respectively. When used for films production, RPS originated transparent films with lower roughness and wettability than CPS-based films, but with higher stretchability. In turn, when combined with RPS and CPS, oil or waxes recovered from frying residues and potato peels, respectively, allowed to develop transparent yellowish RPS- and CPS-based films with increased surface hydrophobicity, mechanical traction resistance, elasticity, and/or plasticity. Therefore, potato chips industry byproducts revealed to have thermoplastic and hydrophobic biomolecules that can be used to efficiently develop biobased plastics with improved surface properties and flexibility, opening an opportunity for their valorization.

The Effect of Endophytic Bacteria Bacillus subtilis and Salicylic Acid on Some Resistance and Quality Traits of Stored Solanum tuberosum L. Tubers Infected with Fusarium Dry Rot

The effect of endophytic Bacillus subtilis (strains 10-4, 26D) and their compositions withsalicylic acid (SA) on some resistance and quality traits of stored potatoes infected with Fusariumdry rot were studied. The experiments were carried out on hydroponically grown Solanumtuberosum L. tubers that were infected before storage with Fusarium oxysporum and coated with B.subtilis 10-4, 26D with and without exogenous SA, and then stored for six months. It has been shownthat 10-4, 26D, 10-4 + SA, and 26D + SA reduced in different levels (up to 30-50%) the incidence ofF. oxysporum-caused dry rot (with the highest effect for 10-4 + SA). SA notably enhanced the positiveeffect of 10-4, while for 26D, such an effect was not observed. All of the tested treatments increasedamylase (AMY) and AMY inhibitors activity in infected tubers, while decreased Fusarium-inducedprotease activity (except in the case of 10-4 + SA, which promoted a slight increase) was revealed.10-4, 26D, and their compositions with SA decreased (in different degrees) the pathogen-causedlipid peroxidation, proline, and reducing sugars accumulation in potatoes after long-term storage.It was also discovered 10-4 and 26D, regardless of SA presence, decrease pathogen-inducedglycoalkaloids α-Solanine and α-Chaconine accumulation and preserved increased levels of starchand total dry matter in infected stored potatoes. The findings indicate endophytic B. subtilis and itscompositions with SA is a promising eco-friendly and bio-safe approach to cope with postharvestdecays of potato during long-term storage; however, when developing preparations-compositionsit should take into account the strain-dependent manner of B. subtilis action together with SA.

Potato Starch Hydrogels Produced by High Hydrostatic Pressure (HHP): A First Approach

Starch-based hydrogels have received considerable interest due to their safe nature, biodegradability and biocompatibility. The aim of this study was to verify the possibility of producing natural hydrogels based on potato starch by high hydrostatic pressure (HHP), identifying suitable processing conditions allowing to obtain stable hydrogels, as well as to characterize structural and mechanical properties of these products. Sieved (small size granules and medium size granules) and unsieved potato starch samples were used to prepare aqueous suspensions of different concentrations (10-30% w/w) which were processed at 600 MPa for 15 min at different temperatures (25, 40 and 50 °C). Products obtained were characterized by different techniques (light and polarized microscopy, Fourier transform infrared spectroscopy (FTIR), rheology and differential scanning calorimetry (DSC)). Results obtained so far demonstrated that potato starch suspensions (20% starch-water concentration (w/w)) with granules mean size smaller than 25 µm treated at 600 MPa for 15 min and 50 °C showed a complete gelatinization and gel-like appearance. Potato HHP hydrogels were characterized by high viscosity, shear-thinning behavior and a highly structured profile (G' >> G''). Moreover, their FTIR spectra, similarly to FTIR profiles of thermal gels, presented three absorption bands in the characteristic starch-gel region (950-1200 cm-1), whose intensity increased with decreasing the particle size and increasing the processing temperature. In conclusion, potato starch hydrogels produced by HHP in well-defined processing conditions exhibited excellent mechanical properties, which can be tailored according to the requirements of the different applications envisaged.

Physicochemical, functional and morphological characterization of starches isolated from three native potatoes of the Andean region

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Significant differences in characterization of starches were observed among them.

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Imilla negra starch exhibited the highest apparent amylose and phosphorous content.

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Imilla negra starch presented higher resistant starch content in cooked starch.

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Loćka starch had the lowest apparent amylose content and higher crystallinity.

Three varieties of native potato (Imilla blanca, Imilla negra and Loc’ka) that grow in the Andean region at more than 3800 m.a.s.l. were selected fot the extraction and characterization or their starch. Instrumental techniques such as scanning electron microsocopic (SEM), differential scanning calorimetry (DSC), Fourier transformed infrarred spectroscopy (FTIR), X-ray diffraction, colorimetry and polarized light microscopy were used. The results showed that only Loc’kás starch had a unimodal granule size distribution, whereas Imilla negra and Imilla blanca starches showed two and three granule size populations, respectively. The starch from Imilla negra showed higher apparent amylose content, peak viscosity, phosphorous content and paste clarity. The starch from Imilla blanca showed high relative crystallinity, while Imilla blanca and Imilla negra had higher intensity ratios than that from Loc’ka, suggesting high molecular order. Cooked starch from Imilla negra showed higher resistant starch (RS) fraction than the other starches studied.

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.

Potato starch oxidation induced by sodium hypochlorite and its effect on functional properties and digestibility

The effects of different concentrations of sodium hypochlorite (active chlorine content at 0.1, 0.2, 1.0, 2.0, 3.0, and 4.0 g/100 g) on the properties of potato starch (PS) were investigated by determining the morphological, physicochemical, crystallinity, pasting, gel texture and digestive properties. The starch granules of PS oxidized with high oxidant concentrations caused cracks and pores, and oxidation mainly acts on the amorphous regions of the starch granules. As the sodium hypochlorite concentration increases, the carbonyl content, carboxyl content, solubility, and pasting temperature of PS increased, as measured using a Rapid Visco Analyser (RVA). The swelling power, breakdown, setback, and peak and final viscosities decreased according to the RVA (P<0.05). The gel strength increased under low-intensity oxidative treatments and decreased under high-intensity oxidative treatments. Oxidative treatment decreased the digestibility of gelatinized potato starch. The slowly digestible starch and resistant starch contents increased significantly, while the rapidly digestible starch content decreased after the oxidation modification (P<0.05). Overall, PS oxidation with sodium hypochlorite improved the functional characteristics of starch and decreased starch digestibility.

Effect of α-Amylase Degradation on Physicochemical Properties of Pre-High Hydrostatic Pressure-Treated Potato Starch

The effect of high hydrostatic pressure (HHP) on the susceptibility of potato starch (25%, w/v) suspended in water to degradation by exposure to bacterial α-amylase (0.02%, 0.04% and 0.06%, w/v) for 40 min at 25°C was investigated. Significant differences (p < 0.05) in the structure, morphology and physicochemical properties were observed. HHP-treated potato starch (PS) exposed to α-amylase (0.06%, w/v) showed a significantly greater degree of hydrolysis and amount of reducing sugar released compared to α-amylase at a concentration of 0.04% (w/v) or 0.02% (w/v). Native PS (NPS) granules have a spherical and elliptical form with a smooth surface, whereas the hydrolyzed NPS (hNPS) and hydrolyzed HHP-treated PS granules showed irregular and ruptured forms with several cracks and holes on the surface. Hydrolysis of HHP-treated PS by α-amylase could decrease the average granule size significantly (p <0.05) from 29.43 to 20.03 μm. Swelling power decreased and solubility increased with increasing enzyme concentration and increasing pressure from 200-600 MPa, with the exception of the solubility of HHP-treated PS at 600 MPa (HHP600 PS). Fourier transform infrared spectroscopy (FTIR) showed extensive degradation of the starch in both the ordered and the amorphous structure, especially in hydrolyzed HHP600 PS. The B-type of hydrolyzed HHP600 PS with α-amylase at a concentration 0.06% (w/v) changed to a B+V type with an additional peak at 2θ = 19.36°. The HHP600 starch with 0.06% (w/v) α-amylase displayed the lowest value of To (onset temperature), Tc (conclusion temperature) and ΔHgel (enthalpies of gelatinization). These results indicate the pre-HHP treatment of NPS leads to increased susceptibility of the granules to enzymatic degradation and eventually changes of both the amorphous and the crystalline structures.

Extraction of RNA from fresh, frozen, and lyophilized tuber and root tissues

A method for isolating transcriptionally competent RNA from fresh, frozen, and lyophilized plant storage tissues containing high levels of starch and phenolics is described. The protocol avoids the use of guanidium salts, which often lead to the formation of a viscous gel during extraction of high starch-containing tissues, and instead uses a borate-Tris buffer in combination with high concentrations of NaCl, Na2SO3, and sodium dodecyl sulfate in the extraction medium. RNA was extracted from fresh, frozen, and lyophilized tissues of potato tubers, storage roots of sweet potato, radish, and turnip, and rhizomes of ginger. The yield of RNA from potato tubers averaged 281 microg g fresh weight(-1) and 1584 microg g dry weight(-1) from frozen and lyophilized samples, respectively. A260/A230 ratios of potato RNA extracts were 2.2 or greater, indicating minimal contamination by polyphenols and carbohydrates. Similarly, A260/A280 ratios exceeded 1.9, demonstrating minimal contamination of the RNA by tuber protein. While A260/A280 ratios of extracts from the other plant species were somewhat lower than those for potato (average = 1.56 and 1.80 for fresh and lyophilized samples, respectively), A260/A230 ratios averaged more than 2.0, and the RNA extracted from fresh and lyophilized samples of all species was intact, as demonstrated by denaturing agarose-formaldehyde gel electrophoresis. The protocol yielded RNA suitable for downstream molecular applications involving reverse transcription-polymerase chain reaction from all five species. Transcriptionally competent RNA was also recovered from lyophilized potato tuber tissue stored for 6 years (ambient temperature) by a simple modification to the protocol involving extraction in cold acetone. Lyophilization can thus be used to preserve RNA in high starch- and phenolic-containing plant tissues for studies on gene expression.