Schwefeldioxidaufnahme bei der Maisquellung. Ergebnisse von Betriebsversuchen

The results of these tests demonstrated moreover that the low sulfur dioxide contents of the starch which had been achieved in laboratory extraction methods are not achieved by industrial process, even with an elimination of sulfur dioxide during the refining steps. The reason for these differences may be seen in the fact that during industrial processing a starch-water-ratio has to be checked for of technological, ecological and economical reasons, which is impossible to achieve during laboratory tests. Adsorption of SO₂ During Swelling of Maize. Results of Plant Tests. During investigations in four German starch plants the already experienced results could nearly be fully confirmed even without an addition of sulfur dioxide during the refining steps. At a high variability of the plant results a general mean value of 23,7 mg SO₂/kg had been found for dried starch. In these investigations the highest test value for the sulfur dioxide content was still at almost 47 mg/kg. By comparison, with unaltered processing the general mean value of three plants came to 46,6 mg SO₂kg.     

Use of commercial protease preparations to reduce protein and lipid content of maize starch

A method was developed to produce pure maize starch from maize flour using a protease processing step, and additional salt washing and sulphite steeping steps. A range of commercial protease enzymes were evaluated for this purpose. The laboratory scale procedure that was developed, using one protease in particular (Promod P25P, thermolysin), produced relatively pure starch (<0.45% protein). Using the same procedure, but applying to starches which had been produced in advance using traditional wet milling, starch protein contents could be reduced further by 25–50% with the lipid content reduced by up to 25%. The amount of starch damage was minimal using this approach (<1%). This procedure could be developed industrially for a ‘greener approach’ to starch extraction – although it may still be necessary to incorporate sulphite steeping stages to facilitate protein solubilisation and extraction.     

纤维素酶对玉米淀粉生产中浸泡效果的影响

本研究通过使用纤维素粗酶制剂对湿法生产玉米淀粉的浸泡工艺的影响进行了研究,结果表明,纤维素粗酶制剂能够显著地缩短玉米淀粉生产的浸泡时间,降低了二氧化硫的使用浓度,在0.1%的二氧化硫浓度的浸泡液中添加0.3%纤维素粗酶制剂,作用时间为12h,其淀粉得率为57.0%,而使用传统的逆流法工艺(实验室模拟)浸泡48h的淀粉得率仅为54.1%。     

Schwefeldioxidaufnahme bei der Maisquellung. 3. Einfluß auf die Mikroflora

Absorption of SO₂ During Swelling of Maize. 3. Influence on the Microflora. In order to gain insight into the micro-biological conditions during maize starch production the change in micro-biological germ content of the following products has been examined in three different plants: – Maize before entering the steep tanks and after the end of the steeping process, – Starch suspension before and after the hydrocyclone station as well as before entering the centrifuge, – Wet starch during its discharge from the centrifuge and before entering the drier, – Dry starch after discharge from the drier. It was shown that the number of microorganism remaining in the starch does not solely depend on piloting of the steeping process. Increase of germ number respectively infections at certain stages of production seem to be essential causes for micro-biological contamination of maize starch. Place and degree of this increase of germ number depend on the respective technological pattern.     

Einfluß von Schwefeldioxid auf die Lipide stärke-haltiger Lebensmittel: Mais

Influence of Sulfur Dioxide on the Lipids of Starch Containing: Maize. The present paper shows that sulfur dioxide retards the lipolytic activity during the steeping process of maize. The results show that the hydrolysis of phospholipase A (E.C. 3.1.1.4) which removes one fatty acid from the phospholipide is followed by the phospholipase B (E.C. 3.1.1.5). It is not worthy that the phospholipase A is more affected by SO₂ than phospholipase B. However, other lipides, e. g. galactosyldiglycerides and sterol-containing lipides, showed no observable changes in amount. It is of interest that a relative smaller amount of free fatty acids was extracted with petrolether from maize than the original amount extracted with the same solvent before the storage. Whereas the extracted amount with butanol water did not change markedly. On the basis of this findings it may be concluded that free fatty acids are adsorbed on the starch granules of the maize endosperm.     

Biochemisch-technologische Studien über die Naßverarbeitung von Mais. 7. Mitteilung,Modellversuch zur Bestimmung hydrolytischer Reaktionen durch Maisenzyme während des technischen Maisquellprozesses

Biochemical-Technological Studies on Wet-Processing of Maize. Part 7: Model Test for the Determination of Hydrolytic Reactions by Maize Enzymes during the Technological Maize Steeping Process. In a model test enzymatic activity during the steeping process, which can be derived from the determined activity optima of maize enzymes in connection with the environmental conditions in the maize grain is confirmed. Amylolytic enzymes are qualified for degradation of maize starch only in the first steeping phase. Here, starch being closely linked to the endosperm protein is more stable than “isolated” maize starch. Proteases act throughout steeping time, but their activity decreases towards the end. It is supposed that during the steeping of maize degradation takes place mainly in the outer layers of the maize grain. It leads to a loosening of the linkage between endosperm and the germ on the one hand and the fruit hull on the other hand. These might facilitate the separation of the grain constituents. Proteolysis only plays a minor role for the dissolution of the protein matrix enclosing the starch granules.     

Biochemisch-technologische Studien über die Naßverarbeitung von Mais 3. Mitteilung. Die Milieubedingungen im Maiskorn während des Quellprozesses

Biochemical-Technological Studies on Wet-Processing of Maize. Part 3. The Medium Conditions in the Maize Grain During the Steeping Process.

• 1 According to fundamental methodical examinations the destillation method with use of ground steeped corn is appropriate for the determination of SO₂ content in the interior of the maize grain.

As a result of the high buffering capacity of a maize-water suspension it is possible to judge pH-conditions in the interior of the grain during the steeping process by the pH-value determined in this medium.

• 2 During steeping by the single tank process at first a considerable amount of SO₂ is absorbed by maize components (the maximum after 10 hrs). Later, desorption symptoms begin to show according to the initial SO₂-concentration. The course of pH-values in the maize steeping-water gives reason to believe that at this stage SO₂ adheres to parts of the protein matrix that have become soluble. As a result of the entering SO₂, there occurs an intensive pH-decrease in the maize grain. Near the end of the process, values in both maize steeping-water and maize grain get very close without reaching full identity. Initial SO₂-values of 0,4 % and more inhibit lactic acid bacteria.
• 3 In a technological counter-current process two steeping phases can be distinguished. During the first phase – from the beginning up to the 40th hour – the SO₂ content in the maize steeping water and in the steeping maize increases unnoticeably, but the formation of lactic acid takes place (maximum between 12th and 28th hour). At a certain steeping condition the produced lactic acid can enter the interior of the grain and cause a decrease of pH-value. The second, shorter phase is characterized by intensive SO₂ increase and pH decrease in both maize steeping water and maize. The lactic acid content as well as its new formation are low. The proteindesintegrating effect of the steeping agent, the determining factor for the further processing of the maize, becomes effective at a late stage of the process.
• 4 The lactic bacteries as well as their products of metabolism can enter themselfs in the interior part of the grain, provided that the bacteria concentration in the aqueous medium is high and a certain level of maize stepping is reached. As the portion of the relatif bacterial activity in the grain liquid is 70 % in relation to the maize steeping water, a proteolytic activity of the bacterial enzymes is possible.

     

Über die Technologie der Verarbeitung von Maisgrits zu Stärke

On the Technology of Processing of Maize Grits to Starch. At the production of maize products of a low fat content, such as corn flakes or brewery grits, there results on principle a very fatty maize grit of a farinaceous structure in a quantity of 12 to 30 % which is hard to sell. From these waste grits there can be manufactured a quality starch, which complies with the quality designations with regard to protein, fat, ash, and viscosity. The process newly developed and applied for a patent was tested in an existing factory. By means of an intensive steeping the steeping time can be reduced to 1/4 to 1/3 of the normal maize steeping time. The steeping water is separated free of starch by means of a special decanter. The fat content of the steeped maize grit reduces thereby down to 1/8 of the original value. The steeped maize grit is ground and the resulting milk is treated further like in a normal starch factory, at which the separation of husks and germs is eliminated. The process enables maize mills to process also soft sorts of maize such as a German maize. In this case there results at the dry grinding a high yield of fine, fatty waste grits. Without further processing to starch the grinding of soft sorts of maize would, therefore, be uneconomical.     

A Novel Enzyme Application for Corn Wet Milling

In corn wet milling the raw material is prepared by means of steeping. Steeping is required in order to:

• –obtain the valuable CSL (Corn Steep Liquor),
• –soften the kernel and break the cell walls.

SO₂ is added to the steepwater to inhibit bacterial growth. Depending on the type of corn, the steeping time in a semi-continuous steeping system varies from 36 to 60 h, which is substantially longer than all subsequent steps in the process. The corn comprises phytic acid, which to a large extent ends up in the CSL and constitutes an undesirable component. It has now been found that the problem caused by this phenomenon can be avoided by using phytic acid degrading enzymes during steeping. It has further been found, that by adding phytic acid degrading enzymes together with plant cell wall degrading enzymes to the steep liquor, the steeping time can be reduced considerably in a conventional steeping system and even further in a two stage steeping process, whereby the second steeping stage is carried out after course grinding. Also in case conventional steeping times are applied higher starch yields and lower energy consumption may be obtained.     

Biochemisch-technologische Studien über die Naßverarbeitung von Mais. 2. Mitt. Die Veränderung der Quellwasserzusammensetzung während des Quellprozesses

Biochemical-Technological Studies on Wet-Processing of Maize. Part 2. The Change in the Composition of Steeping Water During the Steeping Process. 1. The time, for which the steeping water stays in a countercurrent steeping battery of 8 tanks, is about 20 h and should not be regarded as the steeping time of maize. 2. The changes in the composition of steeping water (dry matter, SO₂ content, nitrogen substances, reducing substances, mineral substances, lactic acid) have been examined in the normal technological steeping cycle (without interruption of maizemilling), during the 40–50 hours' milling break as well in a laboratory-one-tank system, and from this resulting indications as to the processes taking place within the maize grain have been obtained. From the interior of the grain, substances that have become soluble by secondary reactions (SO₂, enzymes) get into the steeping water beside substances that have been present in soluble form from the very start.     

利用电解水替代SO2改进玉米淀粉生产浸泡新工艺研究

采用电解水代替SO_2以改进玉米淀粉生产工艺。以传统工艺(0.2%SO_2)作为对照,通过酸性电解水(Ac EW)与碱性电解水(Al EW)二次浸泡来提取玉米淀粉。结果表明,最佳提取工艺为Ac EW浸泡43 h后再使用Al EW浸泡5 h,此工艺下淀粉收率最高,达到(67.2±1.6)%,并与传统的湿法工艺(SO2浸泡48 h)的淀粉收率(67.4±1.0)%比较,无显著性差异(P0.05)。     

Einfluß einer mechanischen Bewegung des Maises während des Quellprozesses auf die Ausbeuten

The Influence on the Yields by Mechanical Movement of Corn during the Steeping Process. Using two different corn varieties, U. S. Yellow Corn No. 2 and Kenya White Maize, it was tried to find out — in comparison with the conventional corn steeping process, wether higher starch yields may be obtained by means of mechanical movement of corn during the steeping process with steeping time remaining unchanged, or if equal starch yields may be obtained at as shortened steeping time. Naturally, this requires at least equal quality properties of the obtained starches. Under this premise, respective conclusions have been drawn from the results of laboratory yield determinations and analytical tests. In connection with earlier results several criteria for further possibilities of development in the field are given.     

Effect of Protease Addition on Starch Recovery from Steeped Sorghum and Maize

The effect of protease addition on starch recovery from steeped white regular sorghum (RSOR) compared to yellow maize (YMZ) was determined. An in vitro wet milling method standardized to test dosages from 0 to 1.5 Anson units (AU/100 g grain) indicated that starch yields increased proportionally as enzyme concentration increased. The yields were significantly lower for RSOR. A factorial experiment with a level of confidence of P < 0.05 was performed to study the effect of protease addition (1.25 AU/100 g grain) to coarsely ground kernels for 4 h after 20 h or 44 h SO₂ steeping of whole grains. Calcium oxide (CaO) was used to increase the pH of the steep solution to 5.5 and improve enzyme activity. The in vitro and laboratory tests indicated that the enzyme treatment significantly improved starch yields and recoveries; the effect being more pronounced in RSOR. Protease‐treated kernels yielded 3.2% more starch than those steeped regularly. RSOR steeped for 20 h and then treated with the enzyme for 4 h yielded 6.7% more starch than the counterparts steeped regularly. When steep times were compared, kernels soaked regularly for 48 h produced 1.6% more starch than counterparts steeped for 24 h. The protease treatment reduced the amount of inseparables (gluten‐starch complexes) to zero and also lowered the gluten content of starch by about 1.5%. A comparison of protein and ash contents for the refined starches indicated that the process was more efficient for YMZ than for RSOR and for grains steeped regularly for 48 h. YMZ starch started gelatinization at a lower temperature, required less time to reach peak viscosity and had less shear thinning than RSOR.     

Laboratory Wet‐Milling of Grain Sorghum With Abbreviated Steeping to Give Two Products

Short‐time and no‐time steeping were used in the wet‐milling of grain sorghum to give two products, starch in over 78% recovery (starch basis) plus the remaining grain solids. In the wet‐milling process 1.5 parts of fresh water were used per part of grain to compensate for drying and transfer losses. Starting with 100 g (dry solids) of commercial No.2 grain sorghum, steep time (1—3 h), steep temperature (25—60 °C), and coarse‐grinding speed (7, 500—12, 500 rpm with tip speed of 90.4—150.7 km/h) were varied in a model study; starch recovery, starch lightness (L*), and damaged starch were the responses. Grain sorghum was steeped with twice its weight of process water containing 0.2% sulfur dioxide and the steeped kernels were added to an equal volume of process water and the mixture was ground for 6 min in a Waring blender with blunt blades (d = 3.2 cm). The course‐ground material was sieved (opening 1190 μm) to collect the bran/germ, and the throughs were allowed to stand. The sedimented phase was finely ground by one pass through a plate mill, and the fine fiber removed by sieving (opening 73 μm). The slurry was adjusted to a specific gravity of 1.04, and the starch was separated from the protein fraction on a starch table. The protein fraction was combined with the steep‐liquor concentrate (54% solids) plus the bran/fiber and the fine‐fiber fractions to give the co‐product, which contained 70% moisture (wet basis, wb) and 27% protein (dry basis, db). In the surface response study, recovery of starch ranged from 57 to 89%, starch protein content from 0.4 to 0.5%, and lightness (L*) from 90 to 93. Damaged starch content was constant at around 0.4%. Commercial grain sorghum gave the highest starch recovery (90%) after steeping 2 h at 55 °C and coarse‐grinding at 10, 500 rpm; whereas a food‐grade, a white and a red sorghum gave 85, 84, and 80% recoveries, respectively. The four starches had lightness (L*) values of 93—94 and damaged starch contents of 0.4—0.6%. When the commercial grain sorghum was wet‐ground without steeping in 2 parts of water containing 0.2% sulfur dioxide, a 78% recovery of starch was obtained with L* 93.7 and starch damage 0.5%.     

Comparative Studies on Some Physico-chemical, Thermal, Morphological, and Pasting Properties of Acid-thinned Jicama and Maize Starches

Comparative studies on acid hydrolysis of jicama and maize starch were carried out using concentrations of hydrochloric acid of 1.5%, 3.0%, and 4.5% (w/v), for 3 and 6 h, at 40°C. Native maize and jicama starches showed important morphological, thermal, and structural differences from those of tubers and cereals which potentially offer diverse industrial applications. Jicama starch showed low amylose content (12%) and small size of starch granules. Due to these characteristics, jicama starch was more susceptible to degradation during hydrolysis process than maize starch. Under the experimental conditions employed, the acid degradation was not particularly severe, as shown by scanning electronic microscopy analysis which showed small degraded zones and similar X-ray patterns in both starches. However, jicama starch was more susceptible to acid hydrolysis than maize starch, as revealed by the considerable increase in water solubility index, damaged starch, and crystallinity values. Also, the higher susceptibility of jicama starch than maize starch to the hydrolysis conditions was reflected in the sugar content release during hydrolysis. The relative crystallinity of hydrolyzed maize starches decreased during hydrolysis, while those of hydrolyzed jicama starches increased attributable to the lower amylose content of jicama starch in relation to maize starch. Maize and jicama hydrolyzed starches showed low viscosity values with relation to their native starch counterparts. However, native jicama starch showed lower viscosity values than maize starch, suggesting a lower internal stability of the starch granules during hydrolysis. Both native and hydrolyzed maize starches showed higher enthalpy, T _o, T _p, and T _c values than jicama starch and the broadening of the endotherms decreased during the hydrolysis of both starches.     

Zur Frage der Verwendung von Natriumdisulfit statt schwefliger Säure bei der Maisstärkeproduktion

Sodium disulphite (Na₂S₂O₅) has a less active effect on the extraction of corn colloids. The crude protein content of the colloids amounts to a total of 35%. On the Question of Using Sodium Disulphite instead of Sulphurous Acid in Corn Starch Production.

• 1 Comparative examinations have been carried out on the composition of extracts, which had been abtained by steeping of corn in sulphurous acid, sodium disulphite solution and water, respectively.
• 2 It was found that the presence of chemical reagents in the solution used for the steeping of corn, increases the diffusion of extractive substances (especially of the high-molecular ones) from the corn kernel into the steeping water. The most active reagent in this action is sulphurous acid because of its reducing properties and its faculty of increasing the permeability of the cell walls.
• 1 A certain difference in the effect of sulphurous acid and sodium disulphite solution on the colloidal matter of the corn kernel has been found. The highest total amount of colloidal matter extracted from the corn kernel occurred in the presence of sulphur dioxide. About 50% of the dry matter of the colloids (calculated as crude protein) consists of nitrogenous substances.

Test data show that some more high-molecular non-nitrogenous substances are extracted from the corn in the presence of sodium disulphite (= sodium pyrosulphite or sodium metabisulphite).

• 4 It has been found that the positive effect of lactic acid during evaporation of the extracts consists not only in the formation of soluble lactates, but also in the fact that the high molecular nitrogenous substances are degraded to low-molecular substances which do not precipitate during thickening of the extract.
• 5 Results of the technological testing of sodium disulphite showed that during the manufacturing of starch from corn it is possible to replace sulphur dioxide by this reagent in the steeping process according to the technological structure of the plant.

     

Characteristics of mung bean starch isolated by using lactic acid fermentation solution as the steeping liquor

Physicochemical properties of commercial mung bean starch isolated with lactic acid fermentation solution (LFS) and starches laboratory-prepared by using NaOH, Na₂SO₃ and distilled water as steeping liquors were examined with the aim of elucidating the effect of different steeping liquors on the properties of starches. Results indicated that the amylose content, granular morphology and X-ray diffraction pattern of starches isolated with different steeping liquors did not show obvious differences. However, the LFS-isolated starch had significantly (p < 0.05) higher weight percentage of longer B chains and B₁ chains, a lower weight percentage of A chains and a lower ratio of short-to-long chains in amylopectin than those of the other preparations. Moreover, the LFS-isolated starch showed significantly (p < 0.05) lower pasting viscosity, a higher onset temperature, a narrower temperature range and a lower enthalpy of gelatinization than the other preparations. No significant differences on the physicochemical properties mentioned above were found among the laboratory-prepared starches. The results suggest that mung bean starch is degraded during isolation with lactic acid fermentation solution, which leads to the loss of starch granules with less integrity.     

Verarbeitungstechnische Eigenschaften von Inlandmais. 3. Direktverzuckerung

Processing Properties of Local Maize. 3. Direct Saccharification. The corn grits obtained by dry degermination of 15 grades of corn grown in West Germany were subjected to direct enzymatic saccharification. In comparison with two overseas corn grades, the suitability for hydrolysis of the starch contained in the lowfat grit products has been investigated. Two-step enzymatic hydrolysis with bacterial alpha-amylase and glucoamylase was preceded by a steeping extraction with SO₂ water to remove undesired soluble corn components. Although from the technological point of view results cannot be regarded as optimum, it was demonstrated that the starch of domestic corn grades is as suitable for hydrolysis or even more suitable than overseas grades. It was also found that the lowfat products of the medium-early grades permit a larger starch turnover and, consequently, larger sugar yields than that of the medium-late grades although the average starch content of the latter was higher.     

利用蛋白酶发酵液替代SO_2改进玉米淀粉生产浸泡工艺研究

在确定了地衣芽孢杆菌蛋白酶摇瓶发酵工艺各项参数的基础上,采用改良的实验室生产淀粉方法,将处于产蛋白酶活性高峰期的发酵液添加到玉米浸泡水中,探讨了利用蛋白酶发酵液替代SO_2降解包裹玉米淀粉蛋白质的可行性和工艺条件。结果表明,当玉米在含有0.1%的SO_2(和0.5%的乳酸)的浸泡液中浸泡18h后,加入20%的蛋白酶发酵液继续浸泡6h,淀粉得率为67.79%。与传统工艺相比,淀粉得率提高了9.5%,SO_2含量降低了0.1%,总的玉米浸泡时间由36h缩短至24h。     

Factors Improving the Steeping Process of Corn Grains. Part II. Effect of Enzyme Addition

The effect of addition of proteolytic enzymes to the steeping liquor of corn grains was studied to reduce the steeping period and to obtain starch of low protein content. For this purpose the intact, scratched and broken corn grains were steeped in presence of Alcalase and Neutrase enzymes. It was found that the steeping period decreased by about 50% in case of broken grains, while steeping intact or scratched corn grains in presence of the enzymes gave no effect.