Putranjiva roxburghii oil—A potential herbal preservative for peanuts during storage

Samples of peanut seeds were collected from stores in eastern Uttar Pradesh, India and examined for their associated mycoflora and insects. Fifteen species of fungi and one insect, Trogoderma granarium, were isolated from the samples. Volatile constituents extracted in the form of essential oils from 32 plant species were evaluated against the dominant fungi, Aspergillus flavus and Aspergillus niger, as well as Trogoderma granarium. The oil of Putranjiva roxburghii exhibited the greatest toxicity. The oil was found to be fungicidal and thermostable at its minimum inhibitory concentration (MIC) of 400 ppm. The oil was characterized by the determination of its various physico-chemical properties.

The oil protected the peanut seeds completely for 6 months at 0.25 and 0.38 mL in containers of 250 mL capacity holding 200 g seeds. It did not exhibit any adverse effect on seed germination, seedling growth and general health and morphology of plants. Thus, the oil of Putranjiva roxburghii showed potential as a preservative for peanut seeds against spoilage by fungi and insects during storage.     

Vapours of Acorus calamus oil—A space treatment for stored-product insects

The toxic effects of the vapours of the essential oil of Indian Acorus calamus L. rhizomes on the adults of several stored-product insect pests were studied. The declining order of susceptibility was Callosobruchus chinensis (L.), Sitophilus granarius (L.) and Sitophilus oryzae (L.), with Tribolium confusum J. du V. and Rhyzopertha dominica (F.) being tolerant to all doses and periods of exposure tested in this study. The period of exposure appeared to be the most important factor affecting the efficiency of these vapours rather than the dosage.     

A comparison of the interfacial behaviour of three food proteins adsorbed at air—water and oil—water interfaces

The adsorption behaviour of three food proteins—a soya protein isolate, a sodium caseinate and a whey protein concentrate—at a soya bean oil-water interface has been studied by the drop volume method. The interfacial behaviour has been compared with that at an air—water interface. The kinetics of surface tension decay were evaluated in terms of different rate-determining steps at different ionic strengths and concentrations of the proteins. The ranking order with respect to the surface activity of the proteins adsorbed at an air—water interface was the same as that at a soya bean oil—water interface. In the high concentration range the surface activity of the proteins was higher at an air-water interface than at a soya bean oil-water interface, whereas thereverse was found in the low concentration range. In general, the adsorption of the proteins was more diffusion controlled at an air-water interface than at a soya bean oil-water interface; this suggested that proteins were less folded at the soya bean oil-water interface. A comparison of the rates of the diffusion controlled steps for the proteins at air-water and soya bean oil-water interfaces indicated that the solvation energy gained when caseinates adsorb at the soya bean oil interface was enhanced compared with the other two proteins. This indicated an enhanced loop formation of the caseinate molecules in the oil phase when adsorbing at this interface, as compared with the air-water interface.     

Long term storage of wheat.—II.

Further results are given for changes in wheat being stored for a period of 10 years or more under conditions such as might be used for long-term commercial storage. The effects of low temperature and low oxygen tension, singly and in combination, on the changes in the chemistry and in the baking and physical characteristics of the doughs occurring during storage are being studied. The present paper reports and discusses the changes that have taken place in grain that has been stored for a total period of eight years under the four conditions of the experiment.     

Processing and storage effects on the oxidative stability of hemp (Cannabis sativa L.) oil‐in‐water emulsions

Hempseed oil was used to form oil‐in‐water emulsions, and the effect of heating, storage and light on the oxidative stability of the dispersed phase was investigated. Lipid oxidation rate increased following thermal processing and light exposure, whereas oxidation markers remained relatively unaffected during emulsions storage at 4 °C for 10 days. Induction times of the emulsions were reduced up to 26% and the concentration of thiobarbituric acid reactive substances increased up to 4.5‐fold, depending on the processing conditions. Selected berries as potential sources of natural antioxidants were screened for polyphenol and anthocyanin content in order to investigate their ability to retard lipid oxidation in comparison with a commercially available synthetic counterpart. Raspberry powder extract significantly improved the oxidative stability of hemp‐based emulsion compared with the control and was even more effective compared to a synthetic antioxidant when samples were subjected to heat treatment.     

Plant‐oil‐based lubricants and hydraulic fluids

It is estimated that, at present, approximately 50% of all lubricants sold worldwide end up in the environment via total loss applications, volatility, spills or accidents. More than 95% of these materials are currently mineral oil based. In view of their high ecotoxicity and low biodegradability, mineral oil‐based lubricants constitute a considerable threat to the environment. In contrast, most lubricants and hydraulic fluids based on plant oils are rapidly and completely biodegradable and are of low ecotoxicity; moreover, lubricants based on plant oils display excellent tribological properties and generally have very high viscosity indices and flashpoints. However, in order to compete with mineral‐oil‐based products, some of their inherent disadvantages must be corrected, such as their sensitivity to hydrolysis and oxidative attack, and their behaviour at low temperatures. Various methods to improve the undesirable properties of native plant oils will be discussed. In parallel, government regulations that encourage or enforce the use of bio‐based fluids, at least in ecologically sensitive areas, will help to increase their market share. Using the numerous possibilities for selective breeding and/or chemical improvement of the double bond systems of natural fatty acids by increased R&D, the major obstacles regarding the use of plant‐based raw materials for the production of lubricant base fluids can be overcome and bio‐based fluids should expect a future with increasing market shares. Copyright © 2006 Society of Chemical Industry     

Migration of bisphenol A from can coatings—effects of damage, storage conditions and heating

Bisphenol A (BPA) is an important monomer used in the manufacture of epoxy resins for internal food can linings. Experiments were conducted to investigate the effects of different storage conditions and can damage on the migration of BPA to foods. These experiments were conducted in a systematic fashion by filling empty epoxyphenolic coated cans with four foods: soup, minced beef, evaporated milk and carrots and a food simulant (10% ethanol). Filled cans of each food type or simulant were then sealed and processed using appropriate conditions, before storage at three different temperatures: 5°C, 20°C and 40°C. For each of the storage regimes, 50% of the cans were dented to establish if this would lead to increased BPA migration. Cans were removed from these stocks at intervals of 1, 3 and 9 months storage at 5°C and 20°C or 10 days, 1 and 3 months at 40°C. Some initial problems of heterogeneity between samples was overcome by determining the amount of BPA in food as well as in the can lining. It was found that 80-100% of the total BPA present in the coating had migrated to foods directly after can processing by pilot plant filling with food or simulant, sealing and sterilization. This level was not changed by extended storage (up to 9 months) or can damage, indicating most migration was occurring during the can processing step. There was no noticeable difference, in this respect, between the different foods or the food simulant. Analysis of control samples (foods fortified with ∼0.1 mg kg^-1 BPA and contained in Schott bottles) showed that BPA was stable under both processing and storage. Experiments were also conducted to investigate the potential effects, on the migration of BPA from can coatings, of cooking or heating foods in the can prior to consumption. Food cans were purchased and the food either cooked or heated in the can. BPA was analysed prior to and after the heating/cooking process. It was concluded from the results that there were no appreciable differences in the BPA level before and after cooking or heating.     

Physicochemical and sensory properties of milk fortified with iron microcapsules prepared with water‐in‐oil‐in‐water emulsion during storage

This study investigated the possibility of fortifying iron microcapsule powder into milk and the effects of the fortification on the physicochemical and sensory properties of the products during storage. The iron microcapsules were prepared by the water‐in‐oil‐in‐water (W/O/W) emulsion technique. Fortifying the lower concentrations (0.1–0.3%, w/v) of iron microcapsules into the milk samples did not significantly change thiobarbituric acid values. The L‐values for the milk samples were not significantly influenced by fortifying iron microcapsules (0.1–0.7%, w/v). The overall acceptability scores were not affected when the lowest concentration of iron microcapsules (0.1%, w/v) was fortified into the milk.     

DIMETHYL SULPHIDE—A REVIEW

The sources of dimethyl sulphide (DMS) in beer and their relative significance to levels of DMS which are produced under various brewing conditions, are reviewed.     

WORT ENTEROBACTERIA—A REVIEW

Of the family Enterobacteriaceae, Citrobacter freundii, Enterobacter aerogenes, Ent. cloacae, Hafnia alvei, Klebsiella aerogenes and Serratia species have been detected in fermenting wort. Escherichia coli and animal parasites have not been isolated. As shown by G.C. ratio, DNA base sequence comparison, numerical taxonomy and phage typing, Obesumbacterium proteus shares the same family and is placed in the genus Hafnia as H. protea, with two subspecies. H. protea survives brewery fermentations better than other members of the family and is therefore common in pitching yeast. However, all wort enterobacteria are sensitive to pH values below 4.4 and to a lesser degree to ethanol concentrations over 2% (w/v). Rates of brewery fermentations may be retarded by enterobacteria and the beer pH elevated. Other wort bacteria isolated, species of Achromobacter, Acinetobacter and Pseudomonas, are sensitive to pH and ethanol, and present in smaller numbers in wort than the enterobacteria. Beer flavour with respect to fusel alcohols and esters, volatile sulphur compounds, carbonyl compounds and volatile phenols is seriously influenced by wort enterobacteria. Isolation and enumeration of the enterobacteria in fermenting wort are conveniently carried out on MacConkey agar medium; H. protea colonies grow in 48–72 h at 30°C but the other enterobacteria produce colonies in 20–30 h.     

WORT COMPOSITION—A REVIEW

To provide a detailed picture of wort composition, values for the concentration of individual compounds present in wort have been collated. Information on the compounds is grouped into sections covering total solids, carbohydrates, nitrogenous substances, hop substances, lipids, tannins, sulphur compounds, dissolved oxygen, phosphates, inorganic constituents and other substances. Wherever possible, the effects of variation of grist composition and of mashing and boiling conditions on wort composition are given. Brief notes on the fate of individual constituents during fermentation are also included.     

HOP EXTRACTS—A REVIEW

The production and use of both hop extracts and isomerized hop extracts is reviewed with particular reference to recent advances in hop extract technology.     

Effects of initial albumen quality and mineral oil–chitosan emulsion coating on internal quality and shelf‐life of eggs during room temperature storage

Effects of mineral oil (MO) and mineral oil–chitosan emulsion (MO:CH = 25:75) as coatings on internal quality and shelf‐life of eggs were evaluated during 5‐week storage at 25 °C. Eggs with three different initial albumen qualities [Haugh unit (HU): H = 87.8, M = 75.6 and L = 70.9] were evaluated. As storage time increased, HU and yolk index values decreased whereas weight loss increased. Coating with MO and/or 25:75 MO:CH emulsion could preserve the internal quality for at least 4 more weeks for H‐eggs and at least 3 more weeks for M and/or L‐eggs, all with weight losses <0.92%. All coated eggs had >70% positive purchase intent, and their colour differences at week 0 could not be detected by naked human eye (ΔE^* < 3.0, noncoated eggs as reference). Consumers significantly differentiated freshly MO‐coated from noncoated eggs on overall surface appearance. This study demonstrated that MO and 25:75 MO:CH emulsion coatings could preserve internal quality and prolong shelf‐life of eggs.     

DIACETYL—A REVIEW: PART I—ANALYTICAL AND BIOCHEMICAL CONSIDERATIONS: PART II—BREWING EXPERIENCE

Diacetyl and 2,3-pentanedione are normal products of yeast metabolism and are formed in every brewery fermentation. The desired level in the final beer depends on the particular flavour aimed for but, in all types of beer, flavour defects are caused by excessive concentrations of diacetyl and many brewers might be happy to have no diacetyl in the beer. Recent improvements in analytical techniques show that many of the problems associated with diacetyl are due to the occurrence of compounds which can give rise to diacetyl in the finished beer. These compounds include the so-called “precursor,” acetolactic acid, but possibly other compounds such as the bisulphite addition compound of diacetyl are also involved. Study of the factors affecting diacetyl formation and removal by yeast shows how the concentration of diacetyl in beer can be controlled, and the processes at present used to regulate the diacetyl concentration in beer are described. The yeast strain used, the condition of the pitching yeast, the wort composition, the detailed management of the fermentation and the treatment of the beer during packaging and storage can all affect the diacetyl content of the beer.     

Long-term storage of wheat—III: Some changes in the quality of wheat observed during 16 years of storage

In 1957 1-tonne lots of each of two different types of pest-free dry wheat, Manitoba and Cappelle, (moisture content 11·9 and 12·6% respectively) were placed in bins. The influence of low temperature (4·5 ± 0·5°C) and low oxygen concentration (<2% by vol) during storage, on the grain quality, was contrasted separately and in combination with ambient levels of each. Over a period of 16 yr there has been no significant changes in the mean moisture contents of the wheats. The viability of wheats stored at low temperature has remained at about 96%, but that exposed to ambient temperature fell to 39% for Manitoba and to 14% for Cappelle. Free fatty acid values increased with time in both types of wheat, the rate of increase in the bins at ambient temperature being about twice that in the cooler bins. The wheats yielded satisfactory bread throughout. However, the need to add 20 ppm of potassium bromate, and 224 ppm of fungal alpha-amylase to correct a deficiency of natural alpha-amylase, became apparent after 8 yr storage.

There was no growth of micro-organisms in samples of the dry wheats stored for periods up to 10 yr in tubes pushed into the surface of the main bulks of wheat. Except for Aspergillus, the fungi and bacteria survived better at 4·5°C than at ambient temperature. Numbers of Aspergillus remained almost unchanged at ambient temperature over the whole decade, so the survival of Aspergillus over a considerably longer period under all the conditions studied is quite probable. Some bacteria might also be expected to survive for a long period under all the conditions studied while many other species of fungi might survive at low temperature.

Oxygen concentration had little influence on the changes during storage of either the wheat itself or on the survival of the microflora. Restriction of oxygen however, prolonged germinative capacity at ambient temperature for about four years. Low temperature was more effective generally, in reducing adverse changes than low oxygen.     

THE GENUS ZYMOMONAS—A REVIEW

Published information and experience of the genus Zymomonas is reviewed, and discussed with particular reference to the occurrence, detection and control of the organism in the fermentation industry.     

SACCHAROMYCES DIASTATICUS—A STARCH-FERMENTING YEAST

Work on the yeast tentatively named Saccharomyces diastaticus has justified the separation of starch-fermenting Saccharomyces into a separate species. The name Saccharomyces diastaticus was therefore validated.     

BREWING LIQUOR—A REVIEW*

Among the ions present in brewing liquor, calcium is of outstanding importance because of its beneficial effect, in conjunction with phosphate, in lowering the pH in the mash tun; the bicarbonate ion, which acts in the reverse direction, is undesirable. The effect of ions on flavour is not easy to assess but sodium, magnesium, chloride and sulphate are of importance in this connection. Liquor treatment, involving prior removal of ions followed by addition of hardening salts, is discussed in detail in the context of modern plant operation.     

HEAD AND HAZE—A REVIEW

Recent advances in the fields of head retention and colloidal stability are reviewed both in respect of advances in fundamental scientific knowledge and changes in the techniques of brewing and bottling. Problems of head retention have received relatively little investigation and, although the importance of the proteins of beer is now well recognized, it is by no means yet possible to control their fate in brewing. The recognition of the outstanding role of the “tannins” of beer as factors causing colloidal instability has led to the development of new beer stabilizing techniques which are of commercial importance.