Dormancy in Stored Malting Barley: Quantifying the Rate of Break and the Effect of Cooling

The rate of break of dormancy of the varieties Plaisant, Fanfare, Pearl, Halcyon and Chariot, was examined at storage temperatures of 8, 16, 25 and 33°C. The data was fitted using a probit model and the results were compared with those for three previously tested varieties, Triumph, Blenheim and Pipkin. Three varieties - Plaisant, Fanfare and Pearl - were found to emerge from dormancy more slowly than the slowest previously-tested variety, Triumph, suggesting that breeding programs are not assigning a high priority to the issue of dormancy-break-rate. Data provided by Cochrane was also fitted, quantifying the rate of break for a further three varieties. To make the results more accessible to maltsters and store managers, a three-level banding scheme has been proposed. A second experiment examined whether sudden cooling could induce ‘secondary dormancy’. Samples of Fanfare and Plaisant were stored at 12% and 15% moisture content, and dormancy was broken at 33°C and 25°C. Samples were transferred to 8°C at different times. Cooling did not result in a drop in Germinative Energy. Evidence of ‘secondary dormancy’ was not observed.     

DRYING AND STORAGE TREATMENTS FOR OVERCOMING DORMANCY IN MALTING BARLEY

A batch of deeply dormant Triumph barley was stored at ?18°C. The grain was so dormant that its viability, 97–98%, could not be determined using standard tests. Samples were dried to 12% moisture at various rates by varying the temperature and relative humidity of the drying air. Dried samples were stored at three temperatures (15°, 27° and 38°C). At intervals the germination characteristics of subsamples were determined. Germinability improved with storage time, improving faster at the higher temperatures. However some of the samples stored at 27°C and all the samples stored at 38°C suddenly showed a loss of viability, preceded by a loss in vigour. The rate of recovery from dormancy was independent of the drying regime used. Initially the germinability of the barley was 5–10% (1 ml agar test) and 0–4% (3 ml agar test). Recovery from dormancy was extremely slow at 15°C, so that after a year germination values were around 80% (1 ml agar test) and 45% (3 ml agar test). After 27 weeks the viability of grain stored at 27°C began to decline, germinability was 85–90% (1 ml agar test) and 50–60% (3 ml agar test). At 38°C the initial decline in dormancy was rapid, but germinability fell catastrophically at various times between 3 and 30 weeks storage. Other samples of the same lot of Triumph barley were dried to various moisture contents, 9.4%, 10.3%, 11.0%, 13.0% and 14.5%. These were stored at 38°C. The initial rate of recovery from dormancy was rapid, and was unrelated to the moisture content of the grain. The samples dried to 9.4% and 10.3% m.c. achieved germination values close to the viability value, around 95% (1 ml agar test) and 90% 3 ml (agar) tests in 15–18 weeks storage and showed no signs of deterioration in 30 weeks. Grain held at 11% moisture deteriorated after 12 weeks and that stored at 13% and 14.5% deteriorated after 3 weeks. The germinabilities of the samples dried to 9.4% and 10.3% and stored for 15–18 weeks at 38°C were so good, reaching maximal values at 2 days in the germination test, that it is concluded that they could probably not be matched by samples stored cool. The possibility of using higher storage temperature to overcome dormancy and water sensitivity more rapidly, is discussed. Experiments with other grain samples have confirmed that, in most respects, the original barley was typical of deeply dormant Triumph. Samples of Carmargue and Golden Promise matured much more rapidly than Triumph. However water sensitivity was extremely persistent in a sample of Doublet.     

PREDICTING THE GERMINATIVE ENERGY OF DORMANT MALTING BARLEY DURING STORAGE

The management of dormant barley stocks for malting requires a method of predicting germinative energy under given conditions during storage. A method of quantifying the relationship between storage temperature and the dormancy period is developed based on probit analysis. The experimental data were obtained using Triumph barley. The conditions covered in the experimental work were 8°C to 38°C storage temperature at 12% moisture content, wet basis. Combined use of the dormancy model with an existing viability model allows the prediction of germinative energy as a function of storage temperature and moisture content given the initial germinative energy and capacity values. The effects of storage temperature on the variation in germination over time of dormant bariey samples with various initial germinative capacities, and storage moisture contents are investigated using the model. The results indicate that storage at moisture contents below 12% give significant increases in the germination level that can be achieved.     

Monitoring a Commercial Barley Store in the North of England and Comparison with a Computer Simulation of Germination

The temperature, moisture and germination variations in a commercial barley store were monitored over two seasons. Initial mean temperatures of 49 and 46°C were observed. These were higher than the safe temperatures for germination predicted by the computer simulation, but still produced maltable barley. This suggested that the model was too conservative. During cooling the air was heated and the bed dried by an average of 1.5%. This ‘dryeration’ effect helped the barley to withstand the higher temperatures. Differential fan control and off‐peak running were tested and the higher 6°C differential control was shown to reduce rewetting. However, lower and more uniform temperatures were achieved with a 2°C differential. The downward flow system was essential to avoid condensation and did not pose any other serious problems. Some of the maltsters' reservations regarding cooling below 15°C, due to concerns over secondary dormancy and reheating to steep temperatures, should be alleviated by this work. Given the range of fan control options that still need to be investigated, computer simulation of the cooling, drying and germination in storage is recommended as a lower cost option than commercial testing.     

Temperature Affects Astringency Removal and Recurrence in Persimmon

Astringency was removed from‘Triumph’persimmons by immersion in water at 40°C for 5 hr or 60°C, for 1 hr. Similar treatments at 20° and 80°C, had no effect on astringency reduction. Subsequent application of 80% CO₂ for 48 hr was effective for 20°C-treated fruit but not for 80° C-treated fruit, which became nonastringent only after exposure to acetaldehyde. Extending the 60°C treatment beyond 2 hr resulted in recurrence of astringency, which was not reduced by subsequent CO₂ treatment. Astringency also recurred in CO₂-treated non-astringent fruit, when exposed to high temperatures. The disappearance and recurrence of astringency correlated with amount of methanol-soluble tannins.     

THE INTERACTION OF DORMANCY AND WATER-SENSITIVITY OF BARLEY WITH TEMPERATURE

Newly-harvested Scotch barley was dried and put into storage at 90, 100, 110 and 120° F. One sample at each temperature was cooled at a slow rate (2° F./week) and one at a fast rate (2° F/day). The loss of dormancy and water-sensitivity was followed throughout the drying and storage periods. Dormancy and water-sensitivity were lost most rapidly at high drying and storage temperatures. The optimum drying and storage conditions produced a non-water-sensitive, non-dormant barley within 14 days of harvest. Calculation of regression coefficients for percentage loss of dormancy and water-sensitivity per day at average storage temperatures enabled activation energies to be calculated for the two processes. These were 17·5 and 18·3 kcal/mole respectively. Two very similar processes are therefore involved in dormancy and water-sensitivity and their removal.     

The effect of temperature on the lactic acid fermentation of rye flour

A brew (1 rye flour: 2 water) was fermented by its indigenous microflora at temperatures (T) of 10, 15, 20, 25, 30, 35 and 40°C. A direct relationship was observed between the fermentation temperature and the absolute values of the ‘b' (the t coefficient) and ‘c' (an indicator of the width of the parabola) parameters of the fitted quadratic equations: pH=a+bt+ct². Setting the first derivative of the quadratic fitted function to zero, dpH/dt=b+2ct=0, and solving for t gives the duration of the lag-phase period. When the temperature was increased from 10 to 35°C, the lag phase period (no net change in pH) of the fermentation was reduced by >sixfold from 17.8–2.9 h and the fermentation time to attain a pH of 5.0 was reduced by >13 times from 132–9.9 h. The fermentation rate (F) of rye flour within each of the three periods increased as the fermentation temperature increased up to 35°C. To predict the fermentation time to pH 5.0 at temperatures other than these examined in this study but within the range of these temperatures an exponential function, t_5.0={exp[a+(b×T_0.5)+c×exp(−T)}, was fitted. The Arrhenius plot of the acid production rate ([H⁺] h⁻¹) vs the reciprocal of the absolute temperature showed a ‘breakpoint' at 15°C; indicating that 15°C may be the minimum metabolically efficient temperature for the lactic acid fermentation of rye flour. The activation energy (E_a) was 1.4 and 16.0 cal mol⁻¹above and below the 15°C breakpoint; an additional indication that at temperatures <15°C the fermentation is less metabolically efficient.     

Farm‐Scale Experiments to Compare Infestation and Quality Changes in Malting Barley Stored at Three Moisture Contents

Comparison of changes in temperature, moisture content, infestation and germination were made in six aerated 20 t bins of malting barley. Two were at about 13.5% moisture content, three at about 15.5% moisture content, and one at about 16.5% moisture content. The grain started at between 20–25°C and, during aeration, fell at a rate dependent on the moisture content, damper grain being cooler, presumably due to evaporative cooling. The ‘high’ moisture content grain was often over 5°C cooler at 1m and 2m than the ‘low’ moisture content bins. Moisture uptake at the surface was related to bulk moisture content and trends in mite population changes were related to moisture content. Mite population achieved highest numbers at the grain surface but usually before the moisture content absorption was at its peak. They were commonest in the ‘high’ moisture content bin and least numerous in the ‘low’ moisture content bins. There were no apparent differences between bins in the numbers of insects trapped, for instance they were not less numerous in the coolest ‘high’ moisture content bin. However, the trends of numbers trapped followed a similar pattern in all bins; normally O. surinamensis and S. granarius only began to decline after nine weeks storage in December when temperatures fell below 10°C. Germination loss at the surface of the dampest bin was sufficient to cause rejection of the entire bulk for malting. Micromalting indicated that yield of extract and friability were particularly affected by the changes at the surface of the dampest barley.     

青稞品种对青稞发酵酒营养与感官品质的影响

本研究以7种西藏特有的青稞品种及相应发酵青稞酒为对象,基于理化性质、营养、风味和感官等指标,采用典范对应分析（canonical correspondence analysis,CCA）和主成分分析（principal component analysis,PCA）等探究青稞品种与其发酵酒品质的关系。研究表明,与青稞原粮相比,青稞酒体氨基酸中必需氨基酸占比增加,可能是酿造过程中非必需氨基酸转化形成了必需氨基酸。CCA结果显示不同品种青稞原粮在总氨基酸、γ-氨基丁酸、β-葡聚糖和总多酚含量等方面具有一定相似性,但其营养结构的差异经微生物生物化学转化得以放大,为筛选青稞酒的优质品种提供了可能。通过青稞原粮及相应青稞酒中的蛋白质、氨基酸、γ-氨基丁酸和总多酚水平等营养指标分析初步优选出‘藏青2000’为酿酒青稞品种,其次是‘隆子黑’‘芶芝黑’‘藏青25’。结合青稞酒营养、风味和感官等多维度指标,最终确定‘藏青2000’为最佳酿酒青稞品种,其次为各具特色风味的‘芶芝黑’‘隆子黑’‘藏青25’。本研究可为我国青稞酒领域的发展提供参考。     

Effects of CO2 and O2 shocks at high temperature on postharvest quality of cold‐stored citrus fruit

The effect of CO₂ or O₂ shocks at high temperature on the quality of citrus fruits stored at 5 °C for up to 6 weeks followed by shelf life of 1 week at 20 °C was investigated. ‘Ortanique’ and ‘Nadorcott’ mandarins exposed to 95 kPa CO₂ at 33 °C for 24 h showed apparent rind physiological disorders and a global loss of fruit quality. Exposure to CO₂ concentrations up to 50 kPa at 33 °C for 24 h did not adversely affect mandarin quality. Moreover, the treatment of mandarins and ‘Valencia’ oranges with 15 kPa CO₂ and 30 kPa O₂, respectively, both at 33 °C for 48 h, reduced weight and rind firmness loss and prevented the accumulation of fermentative volatiles on cold‐stored fruit.     

LABORATORY EXPERIMENTS TO COMPARE THE DEVELOPMENT OF POPULATIONS OF FIVE SPECIES OF INSECT DURING DORMANCY BREAK AND SUBSEQUENT COOL STORAGE OF MALTING BARLEY

The increase off five beetle species on 50 g of barley was investigated in the laboratory, under conditions simulating grain dormancy break between 20 and 40°C at 5°C increments, followed by cooling to 15, 10 and 5°C and culminating with approximately four months storage at 5°C. The species of storage beetles used were Trogoderme granerlum Everts, Oryzaephilus surinamensis (L.), Cryptolestes ferrugineus (Stephens), Rhyzopertha dominica (Fabricius), and Sitophilua granarius (L.) . At 40°C, only small numbers of T. granarium larvae developed but at 35°C, this species produced very large populations of larvae. At 30°C, O. surinamenals, R. dominica and S. granarius increased moderately while at 25°C the small numbers of O. surinamensis detected were eclipsed by the very large increases in S. granarius which also increased vigorously at 20°C. No adult insects survived in any experiment after four months at 5°C . These results indicate that the best strategy to break dormancy and discourage infestation would be to break dormancy at just above 40°C, followed by rapid cooling .     

The Influence of Barley Storage on Respiration and Glucose‐6‐Phosphate Dehydrogenase During Malting

Malt is produced by the controlled, but limited germination of barley. To produce good quality malt, the barley employed must be able to germinate rapidly and synchronously. Dormancy is a seed characteristic that can interfere with the rapid and uniform germination of barley, thereby reducing the resultant malt quality. Various studies have shown that post harvest storage can be used to remove dormancy and enhance barley germination characteristics and malt quality. Because of its complexity, the fundamental basis of dormancy induction, maintenance and termination remain unknown. Glucose‐6‐phosphate dehydrogenase (G6PDH) is the rate limiting enzyme of the pentose phosphate pathway and has been associated with dormancy decay and increased seed vigor of a variety of different seeds. The aim of this study was to determine if changes in barley germination vigour were associated with respiration and/or G6PDH changes during malting. Commercially grown barley (cv. Gairdner) was obtained from various states of Australia and stored at room temperature for up to 7 months. At 1, 3 and 7 months, samples were taken and stored at ?18°C. The germinative energy (GE) and germinative index (GI) of these samples were measured. Samples were micro‐malted and the α‐amylase activity, respiration rate, and G6PDH activity of the germinating grains were measured at various stages of malting. It was found that storage of barley for up to seven months significantly improved the germination characteristics and increased the α‐amylase activity during malting. However, these improvements were not associated with concomitant changes in respiration rate or G6PDH activity during malting.     

Changes in Germination and Malting Quality During Storage of Barley

To increase brewing yield and efficiency, malts with high extract values, high enzymic activities and good modification are essential. To produce malt that meets these requirements, the barley employed must have minimal post‐harvest dormancy and be able to germinate vigorously. The aims of this study were to determine the extent to which some Australian barley varieties changed during post‐harvest storage, how these changes influenced germination characteristics, enzyme production and malt quality, and, of the germination tests examined, which gave the best indication of a barley's malting potential. Four commercially grown barley samples were obtained, one from Tasmania and three from Victoria. Each sample was stored at room temperature for one year. At monthly intervals, samples were taken and placed at ?18°C. The germinative energy (GE) and germinative index (GI) of these samples were measured. Samples were also micro‐malted and the quality of the malt was assessed using standard EBC methodology. Storage at room temperature positively influenced the germination characteristics of all samples, with concomitant improvements in hydrolytic enzyme production during malting and in a number of malt quality parameters. It was found that, of the germination tests examined, the GI consistently correlated with enzyme activities during malting and with various malt quality parameters thus indicating that the GI is a good indicator of malting potential.     

Steeping of Barley Starch. Effects on Physicochemical Properties and Functional Characteristics

Starches isolated from 3 barley varieties (Glacier, High-amylose Glacier, Waxy Compana) were steeped at 25°, 40° and 50°C for 1 and 3 days. Enzyme susceptibilities, water binding capacities, swelling powers, solubilities and gelatinization temperatures were determined. The extent of change in physicochemical properties due to steeping varied with type of barley starch. Generally, gelatinization temperature increased and the range narrowed as the temperature and the duration of incubation at a specific temperature increased. Swelling power was inversely related while solubility was directly related to amylose content. The treatment had little effect on swelling powers but restricted solubilities. Steeping of Glacier and Highamylose Glacier barley starches produced a more pronounced V-pattern indicating increased amylose-lipid interaction. Cakes baked with Glacier barley starches treated at 25° and 40°C up to 3 days were acceptable; starch treatment at 50°C caused collapse of cakes. Starch treatment caused high initial consistencies of fillings which were reduced during storage.     

Physiology and Microbiological Quality of Fresh-cut Mango Cubes as Affected by High-O2 Controlled Atmospheres

Preliminary study showed that among 40‐ to 100‐kPa O₂ atmospheres, 60‐kPa O₂ reduced the respiration of fresh‐cut ‘Carabao’ mango cubes the most when held at 5 °C or 13 °C for 42 h. Therefore, the effects of 60‐kPa O₂ on the physiology and microbial quality of fresh‐cut ‘Carabao’ and ‘Nam Dokmai’ mango cubes were determined and compared with those held in air. The high‐O₂ atmosphere reduced the respiration rate of ‘Carabao’ mango cubes stored at 5 °C but stimulated the rate after 2 d of storage at 13 °C. Browning of ‘Carabao’ cubes was accelerated by 60‐kPa O₂ at 13 °C. With ‘Nam Dokmai’ cubes, the high O₂ had no effect on respiration rate, browning, and incidence of water‐soaked appearance at 5 °C and 13 °C. The high O₂ did not affect texture or ascorbic acid content of ‘Carabao’ and ‘Nam Dokmai’ mango cubes at either temperature. Counts of lactic acid bacteria and molds were below the detection level (2.4 log colony‐forming units [CFU]/g) during storage at both temperatures. However, 60‐kPa O₂ stimulated the growth of mesophilic aerobic bacteria on ‘Carabao’ cubes and yeasts of ‘Nam Dokmai’ cubes at 13 °C. The increased microbial count may have been due to the higher pH of cubes stored in 60‐kPa O₂ at 13 °C than at 5 °C or in air. Within ‘Nam Dokmai’ mango cubes, the predominant genera in mesophilic aerobic bacteria were Enterobacter, Klebsiella, and Pantoea and in the yeasts were Candida, Cryptococcus, and Rhodotorula. These results indicate that 60‐kPa O₂ is not desirable for mango cubes when held at 13 °C.     

Colour and anthocyanin stability of red raspberry jam

Anthocyanin and colour stability of red raspberry jams made from two different varieties (‘Zeva’ and ‘Heritage’) were analysed during 6 months, stored at three temperatures (20, 30 and 37°C). Also the influence of freezing the fruit, previously to jam manufacture, was evaluated. Different anthocyanin composition was detected for both cultivars and while ‘Zeva’ fruit had a higher total anthocyanin content, Heritage variety produced jams with a higher redness hue. The development of browning was directly related to storage temperature but not to thawing or the variety of fruit used. © 1998 Society of Chemical Industry.     

Breeding of lipoxygenase‐1‐less malting barley variety ‘Satuiku 2 go’

The lipoxygenase‐1‐less (LOX‐less) trait has positive effects on beer quality, in particular, improvement of flavour stability related to the reduction of beer‐deteriorating substances such as trans‐2‐nonenal. ‘Ryohfu’ is the only spring‐sown malting barley variety grown in Hokkaido, located in the northern part of Japan, and has been used in the Japanese brewing industry for over 20 years. ‘Satuiku 2 go’ was developed as the first LOX‐less malting barley variety in Japan by successive back‐crossing with molecular marker‐assisted selection to introduce the LOX‐less trait into the recurrent parent ‘Ryohfu’. The agronomic performance and general malt quality of ‘Satuiku 2 go’ were almost equivalent to those of ‘Ryohfu’. Wort and beer analyses at the pilot‐scale brewing trial indicated that the LOX‐less trait had little effect on the general characteristics. In contrast, the beers made from ‘Satuiku 2 go’ malt exhibited reduced levels of trans‐2‐nonenal and trihydroxyoctadecenoic acid. The sensory evaluation demonstrated the superiority of ‘Satuiku 2 go’ beers stored under differing conditions in terms of staleness. It can be concluded that the LOX‐less trait was effective in different genetic backgrounds of the recurrent parents used for the development of LOX‐less malting barley varieties. Copyright © 2018 The Institute of Brewing & Distilling     

Effect of kafirin protein coating on sensory quality and shelf-life of 'Packham's Triumph' pears during ripening

BACKGROUND: Pears are exported in large quantities from South Africa, resulting in large revenues. Minimisation of quality losses once the fruit has reached the export destination is as important as following strict export and distribution protocols. Kafirin can form edible films. In this study an edible coating made from 20 g kg^?1 kafirin coating solution was applied as a postharvest treatment to retard quality deterioration of ‘Packham's Triumph’ pears during storage at the typical ripening temperature (20 °C). Changes in physicochemical and sensory quality were monitored over a period of 24 days. RESULTS: The kafirin coating was unable to retard the onset of ripening but decreased the respiration rate and retarded the progression of senescence. However, moisture loss was exacerbated in the kafirin‐coated fruit during ripening at 20 °C, especially towards the end of the shelf‐life. CONCLUSION: The kafirin coating extended the eat‐ripe quality of the pears by 1–2 weeks. However, the appearance of the fruit was unacceptable after 14 days of storage in terms of wrinkled skin. Further work is needed to improve the water barrier properties of the kafirin coating by incorporating a wax or triglyceride into the coating formulation or more simply by applying a kafirin coating to waxed fruit. Copyright © 2011 Society of Chemical Industry     

Further studies on SS bonds in cereal glutelins

Flours of wheat, rye, barley, oats, maize and sorghum have been extracted to remove albumins, globulins and prolamins. The SS bonds of the starch-glutelin residues (4 to 8% protein) have been reduced with sulphite and titrated with phenyl mercury acetate (PMA) in the presence of 3 M -guanidine hydrochloride at 37 °C and, in its absence, at 2 and 37 °C. Attention has been paid to several possible sources of error including oxidation and the rate of diffusion of PMA into protein particles. Approximate values for the diffusion coefficients of PMA through cellulose and protein films were obtained. Titrations at 37 °C in the absence of guanidine hydrochloride are unsatisfactory due to reaction of intrachain SS links. Evidence in the literature suggests that the SS bonds titratable at 2 °C are inter-chain, possibly includingsomestrained intra-chain bonds. The results imply that most of the major polypeptide chains in the cereal glutelins examined, apart from barley and sorghum, contain two such bonds. In the case of barley glutelin probably less than half the chains have two labile SS bonds. Most of the chains in sorghum glutelin appear to have a single labile bond and the polymers may contain only a few chains. The molecular weights (in thousands) of the principal polypeptide chains of the glutelins, deduced from gel electrophoresis in sodium dodecyl sulphate (SDS), are: Cappelle-Desprez wheat 44, 41; Manitoba wheat, rye and barley, 44; oats, 33, 23; maize, 23, 19; sorghum, 22, 18.     

Effects of different drying methods on phenolic contents,antioxidant, and tyrosinase inhibitory activity of peach blossoms

Fresh peach blossoms of two varieties were dried by using different methods, which include shade drying, freeze drying, microwave drying and hot air drying (at 30, 60, 90, 120 °C). The effects of different drying methods on phenolic contents, antioxidant and tyrosinase inhibitory activity were evaluated. Among the seven drying treatments, microwave drying yielded the highest contents of total phenolics, flavonoids, anthocyanins, proanthocyanidins and individual phenolic compounds in dried peach blossoms, while hot air drying at 30 °C gave the lowest retention of total phenolics, flavonoids, anthocyanins. As compared with shade drying and freeze drying, hot air drying at 60, 90, 120 °C resulted in higher retention of phenolic content. The highest antioxidant activity in dried peach blossoms was obtained by microwave drying, while hot air drying at 30 °C gave the lowest. The effect of different drying methods on antioxidant activity of dried peach blossoms was consistent with that of phenolic content. The highest tyrosinase inhibitory activity was achieved by hot air drying at 120 °C for variety ‘yingchun’ and 90 °C for variety ‘huangjinmeili’, but there was no significant difference among hot air drying at 60, 90, 120 °C for both varieties. The tyrosinase inhibitory activities of peach blossoms by microwave drying and freeze drying were comparable and much lower than that of shade drying. The results indicated that microwave drying was a desirable method for the preservation of phenolic compounds and antioxidant activity in peach blossoms, while shade drying and hot air drying at high temperature were favorable for tyrosinase inhibitory activity.