THE MAJOR VOLATILE COMPONENTS OF CANE MOLASSES

SUMMARY —The characteristic aroma was found in the basic fraction of an aqueous distillate of cane molasses. Gas chromatographic analysis of this fraction indicated the presence of at least 35 compounds of which 29 were identified. Among these were aliphatic and aromatic esters, aldehydes, alcohols as well as several furan derivatives. The acidic fraction contained at least 11 compounds, five of which were identified as simple aliphatic acids.     

ROLE OF ALPHA-GLUCOSIDASE IN THE FERMENTABLE SUGAR COMPOSITION OF SORGHUM MALT MASHES*

The cause of the high glucose to maltose ratio in sorghum malt worts was studied. Mashing temperature and pH strongly affected both the amount of glucose and the proportion of glucose relative to total fermentable sugars. The relative proportion of glucose was higher when mashing was performed. at pH 4.0, close to the pH optimum for sorghum alpha-glucosidase, than at the natural pH of the mash (pH 6.0–5.5). Mashing according to the EBC procedure using an enzymic malt extract with pre-cooked malt insoluble solids producing a wort containing maltose and glucose in an approximately 4:1 ratio, whereas mashing with a malt extract without pre-cooking the malt insoluble solids resulted in a wort with approximately equal amounts of maltose and glucose. Both treatments gave the same quantity of total fermentable sugars and amount of wort extract. Sorghum alpha-glucosidase was confirmed to be highly insoluble in water. All or virtually all activity was associated with the insoluble solids. Hence, it appears that the high amount of glucose formed when sorghum malt is mashed conventionally is due to alpha-glucosidase activity. Pre-cooking the malt insoluble solids inactivates the alpha-glucosidase, preventing the hydrolysis of maltose to glucose.     

THE AROMA COMPONENTS PRODUCED BY YEAST IN NITROGEN-FREE SUGAR SOLUTION

In nitrogen-free sugar fermentation yeast produces several other volatile compounds in addition to ethanol. Most of these compounds are distilled over with the ethanol. When the aroma components obtained from the ethanol fraction of a nitrogen-free sugar fermentation were compared with the aroma components of whisky, they showed a qualitatively striking similarity. There was a clear difference in the proportions of the components, however, a fact for which the distillation procedure might be at least partly responsible. The distillate obtained from the fermented sugar solution contained iso-amyl alcohol and β-phenethyl alcohol as well as the ethyl esters of caproic, caprylic, capric, lauric and palmitic acids in considerable amounts. The same acids also appeared as main components among the free acids and, further, isobutyric and isovaleric acid were found quite abundantly. The similarity between the aroma compounds formed in nitrogen-free sugar fermentation and the aroma fraction of alcoholic beverages indicates that the yeast is responsible for the bulk of the aroma compounds produced.     

USE of EXPERIMENTAL DESIGN to ESTABLISH OPTIMAL CROSSFLOW FILTRATION CONDITIONS: APPLICATION to RAW CANE SUGAR CLARIFICATION

A methodology based on central composite experimental design is proposed in order to find the optimal operating conditions of crossflow filtration with a new product/membrane combination. This approach provides an optimal operating zone with good security and fewer pilot plant tests than usual. Interesting results are found when this strategy is applied to the clarification of raw cane sugar by using microfiltration with an inorganic membrane. Maximum fluxes are obtained with the lowest transmembrane pressures and highest crossflow velocities. Analysis of data using forward selection stepwise multiple regression is illustrated with respect to classical response surface method.     

DETERMINATION OF THE SUGAR COMPOSITION OF WORT AND BEER BY GAS LIQUID CHROMATOGRAPHY

The Gas Liquid Chromatographic Method for the separation of sugars has been developed to provide a routine quantitative determination of the sugar components in beer and wort, and in sugar-containing brewing adjuncts. Samples for test are dried under vacuum and converted to volatile trimethylsilyl (T.M.S.) derivatives which are suitable for analysis. The peak areas of the sugars are corrected to an internal standard and the concentrations calculated by applying the appropriate detector response factors. By the use of the method, the quantitative determination of fructose, glucose, maltose, maltotriose and maltotetraose in samples can be accomplished at a rate of 6–7 complete analyses per working day with the expenditure of comparatively little actual operator time.     

低糖苦瓜脯渗糖工艺研究

以新鲜苦瓜为原料制作低糖苦瓜脯.通过研究真空度、渗糖温度、渗糖时间、抽真空次数、糖液浓度、冷浸时间对渗糖效果的影响,确定了低糖苦瓜脯真空渗糖的最佳工艺,同时探讨了原料的切分和硬化工艺参数对渗糖效果的影响.结果表明:苦瓜切分为0.7cm～0.8cm环状.20℃饱和氢氧化钙处理2h,填充0.5%的羧甲基纤维素钠,于真空度0.085MPa,60℃下,真空递增渗糖(30%、40%、50%、50%),真空处理4次,每次持续10min,二次渗糖冷浸2h.     

ELECTROPHORETIC SEPARATION OF PROTEINS AND THEIR AMINO ACID COMPOSITION IN RAW AND PROCESSED POTATOES

Potato tubers had 1.67% N/dry matter. Nitrogen was distributed in all anatomical regions of the tuber. Of the total N content, 43% was dialyzable-N and 32.9% true protein-N. The protein, by solubility fractionation, provided 67% albumin, 23% globulin, 1.4% prolamin and 9% glutelins. As revealed by sodium dodecyl sulfate electrophoresis (SDS-PAGE), the albumin had two major protein species, one of 45 × 10³, the second of 12–25 × 10³ daltons. Prolamin and glutelins contained protein bands coinciding in molecular weight with those of albumin and globulin.
Protein hydrolysis with 4 N methanesulfonic acid was superior to that of 6 N HCL. Amino acid composition of proteins was determined by ion-exchange column chromatography. Some minor losses in protein composition of potatoes occurred during processing.     

THE PROPERTIES,COMPOSITION AND FERMENTABILITIES OF WORTS MADE FROM 100% RAW SORGHUM AND COMMERCIAL ENZYMES

A mashing regime was developed using 100% raw sorghum which enabled commercially acceptable hot water extracts to be obtained in 85 minutes with minimal use of a heat stable α-amylase and proteolytic enzymes. This gave worts of HWE 295 1°/kg, with FAN levels of about 40 mg/l and ammonium ion concentration of about 60 mg/l. Higher, but commercially unacceptable, levels of proteolytic enzymes gave worts with FAN from 84.5 to 95 (mg/l). Addition of an amyloglucosidase as the commercial preparation Amylo300L, was required to convert the HWE to fermentable extract. The addition of Amylo300L, increased the DP1, DP2 and DP3 carbohydrate fractions of the worts from 22% to more than 90% of the total, compared to about 80% for a wort made from malted barley without the use of enzymes. Two different proteolytic enzymes gave different extracts and FAN contents presumably reflecting either differences in susceptibilities of the sorghum to the two enzymes or the presence of different additional enzyme activities in the different preparations. The level of ammonium ions in malted barley worts was 86 mg/l and up to 88 mg/l in worts produced from sorghum and enzymes. Enzyme addition produced increased levels of ammonia. The content of Group A (the most readily assimilated) amino acids was proportionally higher in sorghum worts compared to malted barley wort. Worts made from raw sorghum and enzymes, containing as little as 40 mg/l FAN, were fully attenuated. The yeast consumed about 35 mg/l FAN and 45 mg/l ammonium ions. Under identical fermentation conditions, the same yeast, fermenting a malted barley wort of comparable extract consumed 104 mg/l FAN and 37 mg/l ammonium ions.     

THE QUALITY OF BLENDED RAW MILK IN CREAMERIES IN SOUTH-WEST SCOTLAND

The quality of raw blended milk going to manufacture at five creameries in southwest Scotland has been surveyed over a two-year period. Analyses of gross composition, somatic cell count, numbers and types of bacteria present and the concentration of free fatty acid in the milk show that milk quality was of a high standard. However, extended storage of the milk at 6°C indicated that the bacteria in the milk were actively multiplying and the results showed that extended storage of milk at creameries could seriously jeopardize milk quality. The development of lipolysis on extended storage of the milks was associated with the numbers and types of bacteria present in the milk before storage.     

THE NONVOLATILE ACID AND SUGAR COMPOSITION OF MAYHAW FRUITS (CRATAEGUS AESTIVALIS, C. OPACA, C. RUFULA)

Nonvolatile acid and sugar compositions were determined in ten cultivars from three species of mayhaw fruits (Crataegus aestivalis, Walter, Torrey & Gray; C. opaca, Hook. & Arn.; C. rufula, Sarg.). Fructose and glucose were the major sugars and malic acid was the principle nonvolatile acid found in these fruits. Citric acid, quinic acid, sorbitol, sucrose, xylose, and inositol were quantitated but were found in lesser amounts and succinic acid, arabinose, and galactose were trace components in all fruits. Pyruvic acid and tartaric acid were tentatively identified in most cultivars based on GC retention times. The nonvolatile acid and sugar composition among all mayhaw fruit species were very similar although one unnamed cultivar of C. aestivalis had much higher levels of fructose and glucose, and the cv. T. O. Superberry had higher levels of malic acid. Malic acid levels were found to be much higher in mayhaw fruits than the levels reported in other stone and pome fruits. Three cultivars of C. rufula grown under cultivation yielded mature fruit with almost identical nonvolatile acid and sugar composition.