STUDIES ON COLD WATER EXTRACT OF MALTS: SOLUBLE PROTEIN AND MALTING BEHAVIOUR

Modification of the IoB method for Cold Water Extract (CWE) allowed the determination of the CWE and Cold-Water-Soluble (CWS-) protein in 96 micromalts per day by a single operator. The method was used to follow the changes in CWS-protein of malts of four cultivars of barley with increasing modification. Malting and non-malting cultivars were shown to have different patterns of protein solubilisation during malting. The equivalent of a Kolbach determination carried out on Cold Water Extracts of malts of more than three days modification sharply differentiated between malting and non-malting cultivars. Cold-Water-measurable proteolysis was shown not to be the cause of an unexpectedly high malting potential shown by a variety with low Diastatic Power.     

Polygalacturonase (PG) gene expression in <Emphasis Type="Italic">Musa acuminata</Emphasis> cultivars from Kerala

Banana cannot be preserved for a long time after harvesting due to a short shelf life. Fruit softening is associated with textural changes due to disassembly of the primary cell wall and modification of the structure and composition of various polysaccharides. Cell wall degradation is caused by the action of various cell wall hydrolase enzymes. Polygalacturonase (PG) is the key enzyme involved in this process. The ripening period is different in cultivars maintained under domesticated cultivation in Kerala. PG activity was profiled in eight Musa acuminata cultivars from Kerala and expression analysis of the PG gene was accomplished using semi-quantitative RT-PCR. Maximum PG activity was observed in Palayankodan and minimum activity was observed in Kadali. Gene expression analysis showed variation between ethylene treated fruits and controls in Palayankodan, whereas the expression patterns in Kadali were similar. The fruit softening process is cultivar specific.     

Effects of Boiling and Storage on Dietary Fibre and Digestible Carbohydrates in Various Cultivars of Carrots

The influence of boiling and storage on dietary fibre and digestible carbohydrates was investigated in eight different carrot cultivars. The content of total dietary fibre was in the range 252–291 g kg^-1 DW and was generally at the higher end for the early cultivars and at the lower end for the late ones. During storage, there was a decrease in the soluble fibre content in all cultivars and generally an increase in insoluble fibre. Following boiling, the loss of dietary fibre varied considerably between cultivars. After storage, the loss could be correlated to the average root weight of the carrot cultivars. The total content of glucose, fructose and sucrose was rather similar in the various cultivars, whereas their individual distribution differed. Storage had generally minor influence on the sugar content, except in the cultivars Amarant and Bull. On boiling, the loss was solely dependent on the initial sugar concentration. After storage the loss increased, which could be related to the lower dry matter content. The choice of cultivar and storage time is important in interpreting analytical data from carrots and is probably of similar significance in other vegetables when studying effects of heat treatment. © 1997 SCI.     

A COMPARISON OF SOME RAPID TESTS TO ASSESS EXTENT OF MODIFICATION DURING A LABORATORY SCALE MALTING PROCEDURE

Samples of three barley cultivars were assessed following steeping and at daily intervals during flooring. In addition to determination of hot water extract, several rapid tests were performed on small samples, to assess extent of modification. Certain procedures suggested that modification appeared to continue in cv. Triumph, although a maximum extract figure had been reached and this was attributed to cell wall breakdown continuing after the cell contents had been modified. Malt milling energy provided the most rapid assessment of endosperm breakdown and also enabled accurate prediction of hot water extract at any time between two and seven days germination.     

Amylase activities in insect (Aelia and Eurygaster)‐damaged wheat

The extent of modification of wheat amylase activities caused by Aelia and Eurygaster attack on wheat grain was determined in different Spanish cultivars subjected to varying degrees of attack. High variation in diastatic activity and α‐amylase and β‐amylase activities was found between cultivars, but no relationship could be established between these activities and bug damage within cultivars. Scanning electron micrographs of the cross‐section of damaged kemels showed an empty cavity under the bite point. The surrounding cell walls and protein matrix were absent, but the starch granules were intact. Since wheat damaged by Aelia and Eurygaster does not have altered amylase activities, it appears that amylolytic enzymes are not involved in the alteration of bug‐damaged wheat. © 2002 Society of Chemical Industry     

MODIFICATION IN MALTING BARLEY

The patterns and degrees of modification found in the same grains, by successively applying the Calcofluor and Methylene Blue techniques, while similar were not identical. The Methylene Blue technique over-estimated modification in short-grown grains because the dye spread around the sheaf-cells, into cracks, and into mealy regions of the starchy endosperm. Calcofluor gave slightly higher modification scores in more completely modified grains. Reasons for the discrepancies are suggested. Differences in staining indicate that the nature of endosperm degradation caused by enzymes from the scutellum is different to that caused by enzymes from the aleurone layer. Sometimes patches of unmodified endosperm tissue occured adjacent to the aleurone layer between the zones of modification caused by the two groups of enzymes. Modification sometimes extended around cracks in the starchy endosperm. Various patterns of modification were detected. Other patterns indicate that the aleurone sometimes more or less fails to generate wall-degrading enzymes. Both light and scanning-electron microscopy indicated that cell walls of the starchy endosperm become fragmentary, and were totally degraded in completely modified regions.     

A Comparative Study of Phenolic Antioxidant Activity and Flavonoid Biosynthesis‐Related Gene Expression Between Summer and Winter Strawberry Cultivars

Strawberry (Fragaria ananassa Duch.) possesses good antioxidant properties. Phenolic compounds in strawberries, such as anthocyanins and ellagic acid, mainly act as antioxidants. This study aimed to compare the phenolic content and expression patterns of genes involved in flavonoid biosynthesis between summer and winter strawberry cultivars affected by seasonal variation, degree of ripeness, and genotype. Antioxidant activity and the total content of phenols and flavonoids decreased with fruit ripening. Most notably, summer strawberry cultivars showed higher antioxidant activity than winter cultivars. The expression patterns of flavonoid biosynthetic genes tested were cultivar‐dependent and were also affected by ripening. These results help us understand the nutritional and physiological characteristics of selected cultivars and provide a range of information for strawberry consumption.     

Re‐Assessment of the Half‐Grain Modification Method for Assessing Malt Modification

The half‐grain mashing (modification) method proposed by Palmer (J. Inst. Brew., 1975, 81: 408) was reassessed. The intention was to quantify the differences in malt modification in terms of β‐glucan breakdown and clarify the relationship between β‐glucan breakdown and overall modification of the endosperm during malting. This was carried out at 45°C as well as at 65°C, the percentage of weight loss was recorded and the endosperm residue was analysed for β‐glucan content. In general, weight loss was related to modification. Samples, which were modified at higher levels, lost significantly more material during the half‐grain mashing procedure than those which were under‐modified. At a malting process time of 96 h all the varieties had similar weight loss. After mashing the half grains, the β‐glucan contents of the grain residues showed an apparent increase because of loss of non‐β‐glucan materials. However, over the malting period β‐glucan decreased. Chariot malted faster than the other varieties studied. The β‐glucan levels of this variety were reduced by 78% between 48 and 72 h of germination. Significant levels of β‐glucan were degraded and large quantities of starch and protein were released. During the same period of germination, the corresponding samples of Decanter did not show a significant reduction in β‐glucan levels. In contrast, Brazilian variety MN698 lost endosperm material and β‐glucan rapidly by 48 h. These early results suggest that during malting, extract solubilization may or may not accompany β‐glucan breakdown. Therefore, β‐glucan levels in malt cannot be used as an overall index of modification of the endosperm.     

Investigation of Protein Composition of Barley by Gel Electrophoresis and MALDI Mass Spectrometry with Regard to the Malting and Brewing Process

The protein composition of barley partly determines its quality in terms of malting and brewing. For this reason, the water‐soluble proteins of two different barley cultivars were investigated by gel electrophoresis and matrix‐assisted laser desorption/ionization mass spectrometry. Mass spectra were obtained directly from barley extracts by using three matrices. According to the quality of the measured spectra, it was possible to establish which matrix was the most suitable for the analysis of water‐soluble proteins from barley. We found that the protein patterns did not differ significantly between Jersey and Tolar varieties. However, our results showed the influence of the malting process on the posttranslational modification of some water‐soluble barley proteins. These proteins also survive the brewing process and they are very important for the formation and stability of beer foam. Several barley proteins were also identified by proteomic analysis.     

Chemical composition changes in four green olive cultivars during spontaneous fermentation

Changes in some physico-chemical characteristics (pH and free acidity) and chemical composition (sugars, total phenolic and flavonoid contents) of four olive cultivars during spontaneous fermentation in brine were investigated. The cultivars were typical of the Moroccan market: “Moroccan Picholine”, “Languedoc Picholine”, “Ascolana” and “Sevillana”. The physico-chemical changes of olives and brines during fermentation process were monitored. A similar pattern of pH was noticed for the “Moroccan Picholine”, “Languedoc Picholine” and “Ascolana” cultivars with a final pH ranging between 4.4 and 4.6. The profile of free acidity measured throughout fermentation period in brines was in agreement with the pH trend. The concentration of sugars, total phenolic and flavonoids contents in olives flesh and brines during fermentation is reported. The loss of flavonoids, sugars and total phenolic contents in the olive flesh by the end of fermentation process was up to 60%, 63% and 79% in “Languedoc Picholine”, “Sevillana” and “Moroccan Picholine”, respectively. The main phenols identified and quantified in the different brines at the end of brining process were hydroxytyrosol, tyrosol, (+)-catechin and quercetine. The highest total phenolic content and antioxidant activity were obtained in Moroccan Picholine brine after 71 days of fermentation.     

Change in anthocyanin concentrations in red apricot fruits during ripening

Here we report on accumulation patterns of anthocyanins and of β-carotene during fruit maturation, between 82 and 125 days after flowering, of two apricot (Prunus armeniaca L.) cultivars, A3576 and A3751. Both cultivars displayed an intense red colour of the skin but differed in their genetic background. The pigments were extracted from skin and flesh, separately, and analysed using HPLC-DAD-MS. Out of three anthocyanins detected here, the major compound, cyanidin-3-O-rutinoside was present at 75%. The two minor compounds were cyanidin-3-O-glucoside and peonidin-3-O-rutinoside. This is the first time that peonidin-3-O-rutinoside has been detected in apricot fruit. During maturation, A3751 accumulated anthocyanins in both skin and flesh, whereas anthocyanins were present only in the skin of A3576. The skin anthocyanin content was higher in A3751 (296 mg kg⁻¹) than in A3576 (41 mg kg⁻¹). Maximum anthocyanin levels were attained after 108 and 118 days of flowering in A3751 and A3576, respectively, in conjunction with loss of firmness and red colour acquisition on the un-blushed side of the fruit. At the end of ripening, the β-carotene flesh concentration reached 5 mg kg⁻¹ in A3576 and 15 mg kg⁻¹ in A3751. A significant effect of environment was observed on the anthocyanin content in the two cultivars.     

A SIMPLE AND RAPID TEST FOR ASSESSMENT OF ENDOSPERM PROTEIN MODIFICATION DURING MALTING*

A simple test has been developed for the quantitation of endosperm protein modification in malts. Barley meals or ground malts were extracted with a suitable solvent and the clarified hordein extract diluted into an appropriate precipitant. Of a variety of extractants and precipitants investigated, 1M urea-1% (v/v) mercaptoethanol and 1M sodium chloride were respectively found to be most suitable. Under these conditions a turbid suspension forms; the turbidity of extracts decreased progressively during malting. Turbidity was due to selective precipitation of a specific group of “B” hordeins. In an analysis of nine varieties differing in malting qualities, a significant correlation between the reduction in extract turbidity and cell wall modification (Calcofluor staining) was observed at 48 hours' malting. In addition, for each variety examined, protein modification occurred about one day before carbohydrate modification. Analysis of commercial malts and several samples of selected cultivars from regional trials found good correlations between malt turbidities and percent malt extract and Kolbach index. The test is rapid (10–90 mins) and can be used to screen large numbers of samples; since it is simpler than alpha—amino nitrogen or Kolbach index determination, it may be of use in analysis of malts for protein modification.     

COLD WATER EXTRACT OF MALTS: SOLUBLE CARBOHYDRATE AND MALTING BEHAVIOUR

A rapid and simple method for the determination of the carbohydrate fraction of the Cold Water Extract of malts is described. The extraction is preceded by treatment of the malt with barium hydroxide, which is then removed by precipitation with zinc sulphate. This both deactivates enzymes and prevents solubilization of protein. The method was modified so that it was both faster and used smaller samples. A sustainable rate of 80 samples per day can be tested by one operator. This method was used to follow the pattern of modification through malted grain by analysis of pearler residues. Malting and non-malting cultivars differed in the localization of modification through the grain, with modification confined to the outer layers in non-malting cultivars. The method was also used to measure the proportion of soluble carbohydrate formed during malting with increasing modification. The proportion of extract solubilized during malting by malting cultivars was less than that solubilized by feed cultivars.     

Protein in various legume seeds: Electrophoretic comparison after optimized extraction

Seed proteins of seven legume genera (of twelve cultivars) were compared within one gel under different conditions. Meal preparation using a centrifuge mill and dry ice and extraction using ultrasonication proved to be most effective. Also the conversion of protein to monomers by treatment with SDS in an ultrasonic bath at low temperature yielded somewhat sharper bands compared to the usual boiling procedure.Extraction was by water, buffer or directly by SDS. The water extract differentiated between genera and cultivars better than the other two extractants. Standard PAGE for crude water extracts showed patterns, characteristic for genera, but not for cultivars. Clear differentiation between genera and cultivars was achieved by PAGIF in thin-layer gel after dialysis or after loading with SDS. PAGIF gave the best resolution.     

Cultivar identification of Vicia faba (L.) by sodium dodecyl sulphate–polyacrylamide gel electrophoresis of seed globulins

The globulin fraction isolation from Vicia faba seeds of different cultivars and different lines of the same cultivar has been examined by sodium dodecyl sulphate-poly-acrylamide gel electrophoresis (SDS-PAGE). The technique separates the globulin polypeptides into three distinct groups, termed A, B and C, with molecular weights above 46 kD, between 30–40 kD and below 26 kD, respectively. Distinct differences between polypeptide patterns of the different cultivars and of the different lines of the same cultivar were observed in groups A and B, little variation occurred in group C. Gradient zonal isoelectric precipitation was used to separate the globulin fraction of different cultivars into vicilin and legumin. Variation in polypeptide composition between cultivars was observed in both vicilin and legumin following SDS-PAGE. No difference between cultivars was detected in group C polypeptides of legumin.     

TOTAL AND INDIVIDUAL BARLEY (1–3), (1–4)-β-D-GLUCANASE ACTIVITIES IN SOME GREEN AND KILNED MALTS

Total β-glucanase activity was measured in extracts of malts prepared from three winter and three spring cultivars of barley. Samples were taken at intervals during modification and, after 116 hr, from malt kilned to 65°C. Good malting varieties showed highest levels of total β-glucanase activity, with a high correlation (r = 0.926) with HWE. Angora had the highest activity in the intermediate stages of malting, least loss of activity after heating extracts to 48°C for 10 mins and least loss of activity on kilning. Separation of isozymes by HPLC⁹ confirmed the greater heat stability of isozyme II, but, unlike previous studies on Australian cultivars, we found considerable activity of isozyme I after kilning, even up to 85°C. However, total β-glucanase activity was destroyed by heating extracts of all varieties to 60°C. Angora showed the highest proportion of total activity as isozyme II after kilining. Cultivar differences suggested some scope for breeding varieties with increased total activity by combining high activities of each isozyme. The high correlation of total activity with HWE suggests β-glucanase activity as a rapid test of malting quality.     

Microstructural,cooking and textural characteristics of potato (Solanum tuberosum L) tubers in relation to physicochemical and functional properties of their flours

Potato tubers from six different cultivars were freeze‐dried, ground into flour and analyzed for thermal, pasting and textural characteristics (using differential scanning calorimetry, Rapid Visco analyzer and Instron universal testing machine, respectively) to study the relationship between flour characteristics and cooked potato mealiness. The potatoes with higher sensory mealiness scores resulted in flours having lower transition and pasting temperatures, higher amylose content, setback, peak and final viscosity. The flour gels from the mealier potatoes also exhibited higher values of textural parameters such as hardness, cohesiveness, chewiness and springiness. The microstructure of the tuber parenchyma (studied using scanning electron microscopy), cooking and sensory characteristics of potatoes were found to be related to the pasting and textural characteristics of their flours. Potato cultivars with lower mealiness scores, loosely packed cell arrangement, with comparatively large‐size cells and thinner cell walls showed lower values of textural parameters for both raw and cooked potatoes. This information may prove useful for the selection of potato cultivars with desirable textural and flour‐making properties for specific end‐uses. Copyright © 2005 Society of Chemical Industry     

Bleaching of Green Peas and Changes in Enzyme Activities of Seeds under Simulated Climatic Conditions

ABSTRACT: The effects of simulated climatic conditions on green color loss of peas ( Pisum sativum ) and related enzyme activities were investigated. Seeds of 2 green pea cultivars showing different resistance to green color bleaching were subjected to light only, soaking in water without light, and soaking in water with light. Green color loss and chlorophyll loss were highest in seeds soaked in water and exposed to light, less in seeds soaked in water under dark conditions, and least in seeds exposed to light only. Increased chlorophyllase activity was associated with loss of green color and chlorophyll, whereas no significant relationship was found between chlorophyll loss and lipoxygenase or chlorophyll-degrading peroxidase activity. Susceptible and resistant cultivars had significant differences in green color, chlorophyll content, chlorophyll a/b ratio, and chlorophyll degradation kinetics constant when seeds were soaked in water and exposed to light. Enzyme activity was not significantly different between the cultivars. Soaking led to more green color loss, chlorophyll breakdown, and chlorophyllase activity than light exposure. Chlorophyllase may be the key enzyme responsible for green pea bleaching instead of the oxidative chlorophyll degradation pathway with lipoxygenase or chlorophyll-degrading peroxidase.     

DURATION OF FINAL WARM STEEP AS A CRUCIAL FACTOR IN PROTEIN MODIFICATION IN SORGHUM MALTS

Cold water soluble protein (CWS-protein), cold water soluble protein modification index, total non-protein nitrogen (TNPN), small peptide accumulation, free alpha amino nitrogen, carboxy-peptidase and proteinase activities, all protein modification indicators in malts from two improved Nigerian sorghum cultivars were estimated after six days of malting. Grains were steeped in distilled water for a total of 48 h under four different final warm steep (40°C) treatment periods. Cultivar and duration of final warm water steep, plus their pair-wise interactions highly significantly influenced all these protein modification indices. Sorghum ICSV 400 generally exhibited higher FAN, CWS-protein solubilising activity and accumulation, superior amylolytic potential over proteolysis and better protein modification potential over KSV 8. Lower TNPN and TNPN-FAN difference exhibited by ICSV 400 in spite of its higher FAN suggests superior anabolic protein turnover probably due to more efficient peptide translocation process. Proteolytic activities recorded for both cultivars were inconsistent with levels of N-substances obtained suggesting roles for factors other than proteolysis in grain protein modification.     

Durum wheat cultivar traceability in PDO Altamura bread by analysis of DNA microsatellites

Altamura bread is an Italian baking product that obtained the European mark of protected designation of origin (PDO). The varietal requirements of the official production protocol of this bread require it to be prepared from the durum wheat cultivars Appulo, Duilio, Arcangelo and Simeto (single or in combination, accounting for minimum 80%), and eventually other cultivars diffused in the production area. The aim of this work was to set up a microsatellite-based method for verifying the presence of the four required durum wheat cultivars in PDO Altamura bread, also in the presence of other cultivars up to 20%. Ten microsatellites were tested and the combination of the amplification profiles of four of them, characterised by high polymorphism and simple electrophoretic patterns, enabled to distinguish and identify breads from all the possible combinations of the cultivars required for PDO mark. The obtained amplicons were all in the range of molecular weight between 115 and 272 bp, and were analysed by capillary electrophoresis. The contribution of the single cultivars was detectable in the amplification profiles, enabling to verify their presence. The analysis was also effective in the case of additional cultivars.