Potato Starch Technology

Potato starch production encountered drastic changes during the last years, in particular in economics and substrate supply. Because of economically required reductions in subsidisation, production of potato starch will decrease. Changes in technology are characterised by savings in wash water and process water streams that are effected by increased efficiency introduced with new machinery and changed technological concepts. From an ecological point of view, an early and maximum fruit water separation (up to 95 %) based on dilution of gratings with process water and decanter separation allowed to reduce the fresh water supply to 0.4 to 0.5 m³/t of processed potatoes. For economical isolation of potato protein a correspondingly high protein recovery rate (up to 90 %) is essential. Concerning starch extraction, a minimum of 95 % is reached in modern potato starch plants, but optimum engineering (rasping, decanting, sieving) gives recovery rates of 97 to 98 %. In starch refinement, three-phase nozzle separators equipped with wash water supply and constructed for efficient displacement washing allow to achieve a fine fibre removal of 98 % within three separation stages and a final concentration of purified starch milk of 22 to 23°Bé. Potato protein isolates (protein content 83 to 85 %) are produced by isoelectric precipitation combined with heat coagulation while stringent solutions for treatment of de-proteinised fruit water are still lacking.     

Gewinnung von Kartoffelstärke unter Verwendung des Abwassers als Düngemittel

Extraction of Potato Starch Utilizing Wastewater as Fertilizer . In Sweden the method of washing out the starch from the potato rasp with the undiluted fruit juice of the potato has been developed to higher yields of undiluted fruit juice. By concentration on a specially constructed vacuum filter followed by adding of water to the filter cake, the remaining fruit juice can be forced out, so that only about 0.03% N is left in the starch after filtration. This means that from the fruit juice of the potato about 20% remain in the pulp and about 78% in the fruit juice. The fruit juice is spread by vehicles in portions of 2.5–3 mm, what corresponds to about 100 kg N and 150 kg potassium/ha. The required area is about 130 ha/1000t of commercial starch. It was possible to reduce the amount of wash water to 50–100l/t of potatoes by recycling.     

New Developments in French Potato Starch Industry. Stone Removal Through Dense Medium Process,Environmental Protection

The French potato starch industry received a tremendous impetus since the beginning of the 19^th century. At that time it consisted of not less than 550 plants. At the beginning of the 20^th century it became greatly concentrated leading to a final number of five potato starch factories. The simultaneously increased production capacity has enabled the French potato starch industry to rise to the number two position among the potato starch producing nations of Western Europe. Closely connected with this concentration is a simultaneous modernization of the whole agriculture. All the five starch factories are located in the areas with vast cultivation plains where extensively mechanized agricultural operations are prevalent. However, as a result of this mechanization the deliveries of potatoes contain much larger amounts of earth and stones. For this reason a new process for the separation of stones is currently being tested, in order to reduce the up to now necessary amount of washing water by means of an enriched mud and to improve the effect of potato washing at the same time. The five French potato starch factories are equipped with total-continous and total-automatic machines, and they produce a high-quality potato starch. The concentration to large production units, however, has led in places to an increase of waste water amounts. According to official calculations the raining of potato fruit juice on large areas as well as use of aired ponds have led to a 90% superior purification. Protein recovery in connection with a decrease in waste water volumes will make it possible to even surpass the official standard of purification of 95%, approaching a purification effect of 100% in an already predictable period of time.     

Small Diameter Multiple Hydrocyclone for Starch Processing

The traditional application of small diameter multiple hydrocyclone batteries in the starch industry is the refining of maize, wheat, potato, and manioc starch by countercurrent washing in multistage operation. A new type of multiple hydrocyclone battery for these purposes is discussed. Construction details, internal flow passage, selection of construction material, and some operational characteristics of the battery are taken into consideration as well as its easy, handling. As an example of application of a small diameter hydrocyclone system, a new process alternative for manufacturing of potato starch is presented. The process has a fresh water consumption for starch extraction and refining of 300–350 l/t potatoes or ∼ 1.9 – 2.2 t of water per ton of refined DS starch, due to the unique combination of process stages by adapting a hydrocyclone system, screens, and centrifugal separators.     

Residual cyanide concentrations during the extraction of cassava starch

Cassava starch is traditionally extracted on a small scale in many tropical countries. The process consists of wet-milling the washed roots, washing the starch from this milled pulp on vibrating trays or in mixing tanks, sedimenting the starch in wooden canals or concrete tanks and sun-drying the product. This process was analysed during six production runs in two factories. The distribution of cyanide followed a similar pattern in both factories. Most of the cyanogenic glucosides (bound cyanide) in the roots are converted to free cyanide during the milling operation. Between 40 and 70% of the total cyanide appears in the water used to wash the starch from the disintegrated tissue, and between 5 and 10% appears in the fibrous residue used in animal feed. This residue also contains between 12 and 23% of the starch present in the cassava. The eluted starch is allowed to sediment for 1–3 days, after which it contains less than 4% of the cyanide present in the raw material. The dried product contains less than 1% of the quantity of cyanide present in the raw material; the residual concentration is 1–5 p.p.m. The factors involved in the removal of the cyanide during starch extraction are discussed, and their importance to more efficient large-scale processes is indicated.     

A New Hydrocyclone Process for the Production of Potato Starch with Lowest Fresh Water Consumption

A drastic reduction of fresh water consumption for extraction and refining of potato starch was reached in a new process. The undiluted potato rasp is pumped directly into a closed system of pumps and hydrocyclones in which the starch is separated from the fibres and washed out with fresh water. The fresh water consumption is reduced to about 200 l/t of potatoes. Quality and yield of starch are the same as in conventional processes.     

Geringe Abwasserbelastung durch vollständige Nutzung der Kartoffeltrockensubstanz bei der Stärkegewinnung

Low Waste Water Load by Complete Exploitation of the Potato Dry Substance During Starch Production. As a result of mechanized harvesting processes for potatoes, special attention has to be paid in potato starch factories to the neutralization of flotation and washing waters. This means consequent recirculation as well as continuous pull-out of mud and suspended matter before decomposition of the organic material. The main source for pollution of starch waste waters is the biologically valuable fruit juice of the potato. An extensive separation and utilization of this substance leads to considerable relief of the waste water. A number of possibilities for utilization as a function of the processing capacity are discussed in detail. Apart from using it as feed either directly or after fermentation and acetone butanol fermentation, the use of fermented and de-proteinized fruit water concentrate is of importance in technological microbiology, in methane fermentation and feed granulation. Additional purification of the mixed and pre-purified waste waters in activation filter plants, biological ponds or by sprinkling become substantially more easy by two-step separation by means of suitable.     

两性淀粉的制备及在废纸浆抄纸中的增强作用

通过均匀设计实验，考察了在水和有机溶剂混合反应介质中及低温条件下一步法合成磷酸型季铵基两性淀粉的主要影响因素，以及这些因素对两性淀粉阴、阳离子取代度及反应效率的影响，并将两性淀粉作为增强剂应用于废纸浆抄纸，获得了比较满意的增强效果。     

Evaluation of the extraction efficiency for polyphenol extracts from by‐products of green kiwifruit juicing

The health benefits of fruits are attributable in part to their bioactive components such as phenolics and pectic polysaccharides. By‐products derived from kiwifruit processing can be a good source of such bioactive compounds. Extracts were produced using different concentrations of ethanol in water (0%, 30%, 50%, 74% and 96% v/v) from by‐products (skin, residue and pulp) of the green‐fleshed kiwifruit (Actinidia deliciosa‘Hayward’) juicing process. The amounts of phenolic compounds and uronic acid (UA) as well as the phenolic composition in each extract were determined. Results show that different by‐products contained different concentrations of phenolics and pectic polysaccharides. Based on total phenolic contents, 96% v/v ethanol appeared to be the best extraction medium. The 30% or 74% ethanolic dilution was the second best medium for phenolic extraction from skin and pulp/residue, respectively. Water was a good medium for extracting satisfactory quantities of phenolics as well as the highest concentration of pectic polysaccharides. Phenolic profiling by high‐performance liquid chromatography (HPLC) was used to detect individual phenolic compounds in an extract. Results using HPLC showed that alkali pre‐treatment has improved the extraction efficiency of phenolics as a function of alkali concentration, fruit tissue type, extraction media, by‐product preparation method, and class of polyphenols. As a result more efficient methods for both extraction and characterisation of polyphenols could be evaluated.     

Studies on the Carbohydrate Content of Breadfruit (Artocarpus communis Forst) From South-Western Nigeria

The proximate composition of the peel, pulp and core of breadfruit revealed that the highest moisture, ash, protein, fat and crude fibre contents can be found in the core while the pulp contained the highest levels of carbohydrate, starch, nitrogen free extract and organic matter. Total free and reducing sugars were highest in the core and lowest in the peel. Sucrose, glucose and fructose followed a similar pattern as the reducing sugars while the flatus-producing oligosaccharides raffinose (0.1%) and stachyose (0.05%) were present in the core. Only raffinose was present (0.05%) in both the peel and the pulp. Extracted starch from the breadfruit pulp was 58% of the total starch content on dry weight basis with minimal levels of ash, fat, protein and 98.6% starch. The extracted starch was 98% pure and contained only 2.3% damaged starch. The starch swelling and solubility properties showed a two-stage pattern while the Brabender amylograms showed patterns very typical of starches from most normal non-waxy cereals. The kinetics of carbohydrate breakdown under different storage conditions showed a biphasic first order, slow in the first 8h and thereafter accelerated. Carbohydrate breakdown as an indicator of fruit deterioration was highest when breadfruit was stored at room temperature, while there was only a little difference in those stored in water, formaldehyde solution or in the refrigerator.     

DEVELOPMENT OF A SWEETENER FROM BLACK PLUM (VITEX DONIANA) FRUIT

The Black plum (Vitex doniana) fruit was studied in respect of the chemical composition of its edible pulp, and syrup produced by concentration of extracted juice. Organoleptic evaluation was also conducted on the developed syrup. The results show that the edible pulp of the fruit is acidic (PH 5.20), high in moisture (67.9%), sucrose (12.5%) and reducing sugar (7.3%), and fairly rich in vitamin C (28.5 mg/100 g). Temperature of water used for extracting juice from the pulp correlated positively with soluble solids (r=0.86), titratable acidity (r=0.91) and negatively with vitamin C (r=?0.61). The syrup contained higher reducing sugars (51.7%), lower moisture (25.0%), but similar sucrose (12.9%) content compared to the pulp. The soluble solids of the extracted juice and consequently the yield of the syrup varied with water temperature. An optimum temperature of 80°C gave 20% (w/w) syrup per pulp. The syrup compares favorably with sucrose in sensory properties in model foods.     

Effect of processing on potato starch: in vitro availability and glycaemic index

The content of digestible starch (DS) and resistant starch (RS) in processed potatoes was assessed. In addition, the effect of domestic cooking on the in vitro digestibility of starch in this tuber, which may influence the glycaemic response, was studied. Resistant starch in raw potato is high, however different RS values were obtained when processed, ranging from 1.18% in boiled potatoes to 10.38% in retrograded flour. In general, cooked potatoes have high levels of DS. Starch digestibility is improved after processing and it is affected by the cooking methods. Boiled and mashed potatoes showed the highest rate of digestion, on the contrary raw potato was hardly digested. The estimated Glycaemic Index (GI) from the degree of starch hydrolysis within 90 min was in accordance with the reported GI values, for potatoes processed in the same way.     

Der Energieaufwand in der Reibenstation bei der Kartoffelstärkefabrikation

The Energy Expenditure in the Rasp Station of Potato Starch Production. Three different types of potato rasps being used in Polish Starch Industry were tested: ZT-300 “Spomasz” (Poland). Holthuis (Holland), RU 80-500 Nivoba (Holland). Optimum throughputs depending on energy consumption per one ton of potatoes and disintegration factor were determined. The results confirmed the assumption that increase of throughput decreases electrical energy consumption, however is restricted by disintegration efficiency (factor min. 90%). The latter effects quantity of bound starch on potato pulp and yield of potato starch recovery at the same time. The optimum throughputs for the three rasps were determined.     

An Aqueous Alcoholic-Alkaline Process for Cationization of Corn and Pea Starches

To develop a more efficient process for cationization of corn and pea starches, the effects of gelatinization inhibitor, type of solvent and solvent concentration, starch: water ratio, reaction temperature and 2-chloro-3-hydroxypropyltrimethylammonium chloride (CHPTAC) concentration on rate and efficiency of cationization of corn und pea starches in an aqueous alcoholic-alkaline solvent were studied during 24h of reaction time. The use of watermiscible organic solvents in the aqueous alkaline media eliminated the requirement for a gelatinization inhibitor to minimize starch swelling. The alcohol concentrations which produced high reaction efficiencies were 35-75% ethanol or 2-propanol. Optimum conditions for the reaction included 65% ethanol, 50°C and a starch:water ratio of 1:1 (w/w). The degree of substitution (DS) value increased linearly with CHPTAC concentration up to O,2M CHPTAC, but reaction efficiency (RE) decreased at the O,2M CHPTAC concentration. Cationization of starch in the aqueous alcohol solvent would be an alternative to aqueous processes because of the higher DS and reaction efficiencies that were achieved more rapidly and without the aid of other gelatinization inhibitors.     

Interaction of cationic starch derivatives and cellulose fibres in the wet end and its correlation to paper strength with a statistical evaluation

The adsorption onto a softwood pulp of cationic modified starches with a degree of substitution (DS) ranging from 0.015 to 0.130 and native potato starch was investigated using a method based on size exclusion chromatography‐multi angle laser light scattering (SEC‐MALLS). This technique provides information about the amount and molecular composition of the adsorbed starch product such as the AP–AM‐ratio, the average MW and molar mass distribution. Factors influencing adsorption, like the electrolyte content in the suspension and the initial starch polysaccharide concentration, were investigated. Furthermore, hand sheets were made and the resulting mechanical paper strength was tested. Results were analysed statistically using analysis of variance. Representative results were discussed in detail. In general, low‐substituted cationic starch (DS 0.030) exhibited a higher degree of adsorption and resulted in high paper strength when there was a low electrolyte content in the starch–pulp‐suspension. However, high amounts of electrolytes impeded electrostatic interaction of the charged groups of the starch polysaccharides and cellulose fibre due to partial screening and therefore strongly limited adsorption. This resulted in lowered mechanical paper strength. The water quality of the suspensions had little impact on the polyelectrolyte adsorption of the highly substituted cationic starch (DS 0.100). However, paper strength was markedly higher in the case of starch adsorption where there was a high ionic content and when both starch polysaccharides–AP and AM– were adsorbed. The initial starch concentration determined starch adsorption both quantitatively and qualitatively and subsequently paper strength as well. The relation between adsorption behaviour and paper strength was discussed, particularly in the case of 6% initial starch concentration. In deionised water (DW), the low‐substituted starch (DS 0.03) adsorbed onto the pulp to a greater extent with an AP–AM‐ratio similar to that of the initial starch. Moreover, this achieved the best strength properties in contrast to 36 dGH, where less starch adsorbed and that being almost exclusively AP. In water with 36 dGH, the highly substituted starch (DS 0.100) with both the AP and AM was absorbed and this resulted in higher paper strength. In contrast, AM was almost exclusively adsorbed in DW. Increasing the initial starch concentration increased the amount adsorbed while subsequently changing the AP–AM‐ratio towards increased AM adsorption and decreased AP adsorption in the case of DS 0.100 in DW. Exclusive adsorption of AM markedly lowered the development of the paper strength.     

The influence of ripening stage and cultivation system on the total antioxidant activity and total phenolic compounds of yellow passion fruit pulp

BACKGROUND: This work aimed to investigate the influence of both ripening stage and cultivation system on the total phenolic compounds (TPC) and total antioxidant activity (TAA) of passion fruit pulp. TPC extraction was optimized using a 2³ central composed design. The variables were fruit pulp volume, methanol volume and extraction solution volume. TPC was determined using the Folin–Ciocalteu reaction, and TAA using the ABTS radical reaction. RESULTS: The conditions to extract TPC were 2 mL passion fruit pulp and 9 mL extraction solution containing 40% methanol:water (v/v). TPC values increased in the passion fruit pulp during ripening for both cultivation systems, ranging from 281.8 to 361.9 mg gallic acid L^?1 (P?0.05) for the organic pulp and from 291.0 to 338.6 mg gallic acid L^?1 (P?0.05) for the conventional pulp. CONCLUSION: TPC values increased during ripening for both organic and conventional passion fruit. The same was true for TAA values for conventional passion fruit. For organic passion fruit, however, TAA values were highest at the initial ripening stages. These results suggest that antioxidant compounds exert strong influence on the initial ripening stages for organic passion fruit, when TPC still did not reach its maximum level. Copyright © 2012 Society of Chemical Industry     

STARCH AND PECTIC SUBSTANCES AS AFFECTED BY A FREEZE-THAW POTATO GRANULE PROCESS

Changes in total content and fractions of pectic substances and starch were studied in a freeze-thaw process for potato granule production consisting of peeling, steam cooking, hot mashing, freezing and thawing, pre-drying, granulation, drying, cooling and sifting. Pectic substances in raw potatoes (expressed as mg uronide/netted Gem 100g dry wt) were 202.4 for water soluble and only 80 for the calgon-soluble fractions. Water soluble pectic substances increased sixfold after cooking, and calgon-soluble fraction about threefold. Little change was observed in either fraction due to subsequent granule processing steps. There was no indication that pectic substances present in the extracellular matrix could have influenced the processing steps in granule production. Total starch comprised 68.4%/dry wt of raw potato, decreasing slightly after cooking, increasing up to the pre-drying step and stabilizing at a level of 83.7%. In contrast, free water-soluble starch, depended on the processing steps, being lower in cooked unmashed potatoes than in conditioned raw potatoes. Mashing slightly increased starch content while pre-cooling to 5.5°and freezing to −20°C with subsequent thawing to room temperature substantially decreased starch content. Mechanical forces applied in subsequent steps brought about some increase while in the final product the content was related to particle size of the granules. The percentage of broken cells in cooked potatoes mashed at various temperatures appears to be dependent on the free extracellular starch present in cell binding matrix. Broken cell counts were substantially decreased when mashing was performed immediately after cooking at high temperature or when the mash was frozen and thawed. In the latter case determination of Blue Value Index suggested that a decrease in cell binding strength of the matrix occurred due to soluble starch retrogradation.     

Investigations of Hydrocyclones for Concentration of Cassava Milk

The manufacture of cassava starch in medium — scale factories requires large volumes of water and produces equivalent volumes of effluent. The use of hydrocyclones to concentrate starch milk and thereby reduce water consumption in the extraction of cassava starch was investigated. Basic performance data with selected hydrocyclone configurations were obtained in the laboratory and the results showed conclusively that high and efficient levels of starch separation are possible with considerable potential for water conservation and effluent reduction in starch factories.     

Large-scale extraction of rhamnogalacturonan I from industrial potato waste

Potato pulp is rich in dietary fibres and is an underutilised material produced in large quantities by the potato starch factories. Potato fibres are especially rich in rhamnogalacturonan I (RG I). RG I is a pectic polysaccharide with a high degree of branching and until now undegraded RG I has only been extracted in small amounts limiting the application possibilities for RG I. The present paper describes a large-scale extraction process providing large quantities of undegraded RG I readily available. The extraction process includes enzymatic starch removal using purified Termamyl, enzymatic RG I solubilisation using a highly purified polygalacturonase, and finally purification using depth filtration and ultrafiltration. The extracted RG I has a high molecular weight and a monosaccharide composition comparable to RG I extracted by analytical extraction procedures. The large amount of RG I available by the presented method allows for thorough structure-function analyses and tailoring of RG I to specific functionalities.     

Changes occurring in potatoes during cooking and reheating as affected by salting and cool or frozen storage – a LF-NMR study

Low field nuclear magnetic resonance (LF-NMR) was measured continuously during cooking of salted and unsalted potatoes to investigate the effect of salt on the cooking process. The cooked potatoes were subjected to cool storage (1, 2, 24 and 48 h) or frozen storage (1, 3, 5 or 14 days). Upon storage they were reheated in the LF-NMR instrument to investigate the effect of different storage regimes and salt on the state of water in potatoes during a continuous reheating process. In salted potatoes, a broader distribution of T₂ times leaning towards longer relaxation times were observed for extra-cellular/cytoplasmic water at low temperatures during cooking. This could indicate that the extra-cellular space is increased due to salting. In samples subjected to cool and frozen storage an additional free water component was found, which reflects that syneresis occurs as a result of retrogradation. In the frozen samples, the T_2,1 and T_2,2 water populations merge, illustrating an increased cell wall permeability or freeze damage of the cell walls. This is more evident in the unsalted samples showing that the cell walls are stabilized by salt during freezing. In conclusion, the results showed that LF-NMR could monitor the changes during starch gelatinization, starch retrogradation and melting of retrograded starch in salted and non-salted potatoes.