Volatile Reducing Substances Research Articles

Shelf-Life Prediction of Shallot Powder Using Accelerated Shelf-Life Testing (ASLT) Method by the Arrhenius Equation Approach

The storage process of shallot powder can cause a quality decrease. This study aims to estimate shelf-life of shallot powder at various storage temperatures and determine quality changes during storage. This study used a Completely Randomized Design with two factors to determine quality changes of shallot powder, i.e. the coating and storage temperature. The statistical analysis results showed that the coating, storage temperature, and interaction between the two factors affected Volatile Reducing Substances (VRS) levels. The two factors and their interaction do not influence the water content. Shelf-life estimation was performed using the Arrhenius method. Coated shallot powder has a longer shelf-life than uncoated shallot powder. Shelf-life determination was performed based on water content parameters. The shelf-life of uncoated shallot powder was 337 days at 30 °C, 322 days at 40 °C, and 309 days at 50 °C. The shelf-life of coated shallot powder was 353 days at 30 °C, 340 days at 40 °C, and 328 days at 50 °C. The coating process can extend the shelf-life of shallot powder.

PROSES PEMBUATAN PASTA BAWANG MERAH (Allium cepa var. aggregatum) DAN PENENTUAN UMUR SIMPANNYA DALAM KEMASAN GELAS

Shallot is a commodity that is widely used as a spice. The unstable supply and price of shallot causes it requires some further processing. The alternative of shallot processing is shallot paste. The aims of this study were to develop shallot paste formula which had a strong aromaas well as determination of shelf life in a glass jar. This study has several steps, i.e. preparation and characterization of fresh shallot, processing shallot paste , and determination of shelf life shallot paste in glass jar with the ESS (Extended Storage Studies) method. This main research used completely randomized design with two factors: first, the ratio of fresh shallot and shortening, and second, emulsifier concentration. The ratio of fresh shallot and shortening were 2:1, 3:1 and 4:1 with emulsifier concentration of 2, 3 and 4% for each ratio of fresh shallot and shortening. The statistical analysis show ed that the ratio of fresh shallot and shortening affected the FFA (free fatty acid) value. Concentration of emulsifier and interaction between emulsifier concentration and ratio of fresh shallot and shortening affected VRS ( volatile reducing substance ) content of shallot paste. The best shallot paste treatment determined was the ratio of fresh shallot and shortening of 3:1 with emulsifier concentration of 4%. Shelf-life of packaged shallot paste in glass jar was 10 days at temperature 30, 40 and 50 o C. During the storage, FFA value increased and VRS value decreased along with the increase in storage temperature. The increased of FFA value was caused by fat hydrolysis during storage, while the VRS value decreased due to the evaporation of sulfur compounds as flavor components in shallot paste during stir frying. Keywords : shallot paste, emulsifer, shortening, shelf life

Volatile Reducing Substances in Green Tea

Volatile Reducing Substances in Green Tea

HYDROGEN SULFIDE PRODUCTION BY HEATING TUNA MEAT

ABSTRACTHydrogen sulfide production during heating of raw, precooked, and canned tuna was studied by reflux‐trap technique. Raw tuna homog‐enate did not produce hydrogen sulfide gas when heated at less than 90°C. Canned and precooked samples produce substantially higher amounts of H2 S during heating than the raw substrate. Maximum H2 S production rate occurred after 150 min for raw, 90 min for precooked, and 60 min for canned samples. An apparatus was devised for quantitative determination of H2 S gas present in a sealed can of tuna. Cans of control albacore tuna (Thunnus alalunga) packed in water or oil and retorted for 80 min contained higher amount of H2 S than the spoiled cans. Hydrogen sulfide content, volatile acids, volatile reducing substances, and histamine values of both the control and the spoiled canned tuna increased significantly as the retort lime was extended from 80 to 120. to 240 min. Headspace profile of canned tuna volatiles was determined by gas chromatography. Examination of the chromatograms indicated a considerable increase in concentration of volatiles as the retort time was extended from 80 to 120 to 240 min in both control and spoiled substrates.

Spoilage and spoilage indicators in queen scallops (Chlamys opercularis): I. Held in ice

SummaryA number of bacterial, organoleptic and chemical evaluations were made on iced queen scallops in shell over 14 days total. The spoilage flora, qualitative and quantitative, is described. Organoleptic descriptions are given along with determinations of trimethylamine, total volatile bases, volatile reducing substances, glycogen, hypoxanthine, ribose fractions and optical density ratios at 248 nm before and after treatment with ion‐exchange resin. Hypoxanthine showed the most promise as a spoilage indicator while total volatile bases and optical density ratio showed some promise but to a lesser extent.

Effect of gamma radiation on the storage of onions used in the dehydration industry.

AbstractGamma radiation (8000 rad) of fresh onion bulbs, used in the dehydration industry in Egypt, was investigated. Irradiation reduced sprouting of the fresh bulbs but did not affect the rotting of the bulbs, No effects on sugar content or colour (optical density at 330 nm) of the fresh bulbs and dried onion flakes were observed. The irradiated onion had a noticeably lower ascorbic acid content, pungency (measured as volatile reducing substances) and free amino nitrogen content in comparison with non‐irradiated bulbs. Darkening of onion flakes during storage for 8 weeks at 40ºC did not differ when the bulbs were treated with gamma rays before dehydration.

BIOCHEMICAL CHANGES IN SHRIMP INOCULATED WITH PSEUDOMONAS, BACILLUS AND A CORYNEFORM BACTERIUM

White shrimp (Penaeus setiferus) washed with ethanol and sterile water were inoculated with a fluorescent Pseudomonas, non-fluorescent Pseudomonas, Bacillus, and a coryneform bacterium. Washing reduced the microbial load but growth occurred on control samples during refrigerated storage. Samples inoculated with Pseudomonas became putrid 2–3 days sooner than their controls. Addition of coryneform bacteria delayed spoilage. Shrimp inoculated with Bacillus spoiled at the same time as the non-inoculated controls. Inoculation of shrimp with Pseudomonas species (a) retarded development of melanosis; (b) produced volatile nitrogen in the atmosphere surrounding shrimp but only after spoilage had taken place; (c) caused higher levels of water-soluble protein, non-protein nitrogen, and total volatile nitrogen than in their corresponding controls; and (d) reached higher pH levels sooner than the controls. No significant changes occurred in volatile reducing substances. Sterile shrimp juices exhibited more extensive melanosis than juices inoculated with Pseudomonas. No marked changes in amounts of soluble protein or non-protein nitrogen were noted upon storage of inoculated juices. Juices inoculated with Pseudomonas had higher levels of total volatile nitrogen after storage than comparable controls. Proteolysis by the fluorescent Pseudomonas was indicated by major changes in elution profiles on Sephadex G-100. Compared with sterile controls, levels of free amino acids decreased in juices inoculated with Pseudomonas or Bacillus and stored at 5 C.

Effects of Water Quality on Canned Carrots, Sweet Cherries, and Apricots1

Abstract The chelating agents, monocalcium disodium salt of ethylenediaminetetraacetic acid (CaNa2EDTA) and sodium hexametaphosphate (Na-HMP), at 800 ppm, were used for canning ‘Honey Sweet’ carrots, ‘Van’ sweet cherries, and ‘Large Early Montgament’ apricots with water containing 0, 20, 40, 80, and 160 ppm of Ca and 20 ppm of magnesium. The control cans did not contain EDTA or Na-HMP. The canned carrots, cherries, and apricots were stored at 70° or 100°F. Evaluations were made at 60-day intervals for 6 months. All 3 commodities had better organoleptic4 acceptibility when they were canned with CaNa2 EDTA or Na-HMP than the controls. Carrots canned with CaNa2EDTA were firmer and retained better color than those canned with Na-HMP or the controls. The rate of loss of firmness and color increased with time of storage. Retention of firmness, volatile reducing substances, pH, and taste quality was improved in sweet cherries and apricots canned with CaNa2EDTA or Na-HMP.

Bacteriological and shelf-life characteristics of canned, pasteurized crab cake mix.

The bacteriological spoilage characteristics of a canned, pasteurized crab cake mix product stored at various temperatures were investigated. A large number of bacteria, both mesophilic and psychrophilic, survived the pasteurization process. Bacillus and Micrococcus were found to predominate when the product was stored at 30 C (86 F) and 18 C (64 F), whereas Alcaligenes predominated at 2 C (36 F). The product was found to be free of Escherichia coli. Bacterial counts, trimethylamine nitrogen, volatile reducing substances, and ammonia determinations were evaluated as indices of quality for the product. Close correlation was observed between bacterial counts, volatile reducing substance values, and organoleptic tests when the product was stored at 30 C (86 F). The shelf-life of the product was approximately 6 months at 2 C (36 F), 4 days at 18 C (64 F), and 27 hr at 30 C (86 F).

Bacteriological and Shelf-Life Characteristics of Canned, Pasteurized Crab Cake Mix

The bacteriological spoilage characteristics of a canned, pasteurized crab cake mix product stored at various temperatures were investigated. A large number of bacteria, both mesophilic and psychrophilic, survived the pasteurization process. Bacillus and Micrococcus were found to predominate when the product was stored at 30 C (86 F) and 18 C (64 F), whereas Alcaligenes predominated at 2 C (36 F). The product was found to be free of Escherichia coli. Bacterial counts, trimethylamine nitrogen, volatile reducing substances, and ammonia determinations were evaluated as indices of quality for the product. Close correlation was observed between bacterial counts, volatile reducing substance values, and organoleptic tests when the product was stored at 30 C (86 F). The shelf-life of the product was approximately 6 months at 2 C (36 F), 4 days at 18 C (64 F), and 27 hr at 30 C (86 F).

Investigation of Volatile Reducing Substances as an Indicator of Decomposition for Raw and Processed Foods

Abstract Volatile reducing substances (VRS) in foods were determined by an empirical procedure in which volatiles are stripped by aeration from an aqueous extract of a sample, passed through alkaline potassium permanganate, and measured by the extent of permanganate reduction. Experimental parameters were investigated as a step toward developing a standardized procedure. Dilute methanol was investigated as a reference solution, the equipment described in published procedures was simplified, and some operating conditions were controlled. The amount of permanganate reduction increased with length of aeration, but variations in aeration rate from 1360 to 1790 ml/min were not critical. The method was applied to ground beef, shrimp, and peaches. The raw food materials were stored at ice or refrigeration temperatures until they reached a decomposed state. Samples withdrawn at intervals during storage were processed and preserved by freezing or by freeze-drying. The content of VRS in raw samples increased as the foods decomposed. The VRS were partly lost during cooking and completely lost during freeze-drying. Therefore, the VRS content appears to have promise as an index of decomposition for a variety of raw foods and possibly for some cooked foods, but not for foods that have been freeze-dried.

Effects of Maturity and Storage on Physical and Biochemical Changes in Peach and Apricot Fruits

SummaryRedhaven peaches and Large Early Montgamet apricots harvested at three stages of physiological maturity were ripened at 70° F. (21° C.) with and without pre-ripening refrigerated storage at 34° F. (I° C.) for 9 days. Weight and decay losses, pH, flavour appraisal scores, soluble solids-acidity ratio (SS/A), soluble solids, total sugars, volatile reducing substances (VRS), ascorbic acid, and carotenoid contents increased significantly while firmness and acidity, total contents of pectins and tannins decreased significantly with increasing maturation on the tree and during the ripening period of the fruits after picking. However, the soluble solids, sugars, and tannin contents remained almost constant during the ripening of the fruits. The optimum maturity of Redhaven peaches for fresh fruit shipment was characterized by a maximum value of firmness of 13 lb. and a minimum SS/A value of 13. The corresponding values for Large Early Montgamet apricots were 13 and 6. Hard-mature peaches and apricots appa...

Calorimetric Determination of Volatile Reducing Substances

SUMMARY— The iodimetric procedure for determining the amount of reduction of an alkaline potassium permanganate solution which is used as a measure of the content of volatile reducing substances (VRS) has been substituted by a colorimetric one. The net absorbance at 610 mp is determined from the difference in absorbance between the unreacted and reacted 0.02N KMnO4 in N NaOH solution. The microequivalents of reduction corresponding to the net absorbance value is read off a graph showing the linear relationship between the net absorbance and the amount of VRS.

Effects of dehydration processes on flavour compounds and histology of apricots (Prunus armeniaca).

AbstractIt is shown that freeze‐dehydrated products contained the highest quantity of volatile reducing substances and volatile carbonyl compounds. Histological changes were minimal by freeze dehydration as compared with those obtained in other dehydration processes studied.

The most important quality criteria of some home-grown black-currant varieties III. Aroma number, organoleptic evaluation, and degree of ripeness

A study has been made of the quality properties of 12 home-grown varieties of black-currant. Samples were obtained from six localities over a period of three years. The properties studied consisted of the aroma number, the organoleptic evaluation, and the degree of ripeness. As regards aroma number, great variations were noted between the samples. The influence of variety was rather slight. In general, the aroma numbers were higher when the summer was cool and the growing locality more to the north, probably by reason of the losses of volatile reducing substances at higher temperatures. The utility of the aroma number in characterization of quality seems limited in scope. Smell and taste were taken as the main criteria in the organoleptic evaluation. The differences between the varieties were not very great, but in any event a relatively consistent sequence was discovered. Consideration is given to some factors which influence organoleptic properties. The degree of ripeness of the samples, and the effect of this factor on the quality properties, were studied. The degree of ripeness displays a correlation with the corresponding effective temperature totals. Here, the effect of the ripeness factor on the results was only slight, as unripe berries were removed from the samples before analysis. However, some effect may have remained, to some degree influencing the colour strength, but the organoleptic properties to a lesser degree.

Certain Physiological and Biochemical Changes in Greenhouse‐Grown Tomatoes (Lycopersicon Esculentum Mill.)

SUMMARYTomatoes of V. R. Moscow and Fireball varieties grown in a greenhouse varied markedly from previously reported data on field‐grown lots of the same varieties with regards to total titratable acidity, color development, free reducing sugars, pectins, volatile reducing substances (VRS), organic acids, and ascorbic acid. Concentrations of all the nonvolatile attributes except total titratable acidity (%) were low as compared with field‐ripened tomatoes. Lower concentrations of VRS, organic acids (mg/100 g), and sugars (%) considerably affected flavor, aroma, and taste in greenhouse tomatoes. Color (beta‐carotene and lycopene) development was defective. In general, tomatoes grown in the greenhouse were “flat” and tasteless.

BACTERIOLOGY OF SPOILAGE OF FISH MUSCLE. 3. CHARACTERIZATION OF SPOILERS.

A total of 807 bacterial isolates from fresh and spoiling fillets of English sole (Parophrys vetulus) stored at 5 C were classified as to genus and tested for various biochemical activities, including the ability to spoil sterile muscle press juice at 5 C. Production of off-odor, volatile reducing substances, and trimethylamine was used to estimate spoilage. It was found that (i) spoilers could be distinguished from nonspoilers on the basis of the juice spoilage test, (ii) differentiation between spoilers and nonspoilers could not be achieved by means of the usual biochemical tests, (iii) no micrococci, flavobacteria, and "coryneforms" were spoilers, (iv) certain specific subgroups of the genus Pseudomonas consisted exclusively of spoilers whereas others were inactive, (v) the genus Achromobacter likewise consisted of spoilers and nonspoilers, and (vi) "coliforms" could produce spoilage. It was concluded that a method is now available to determine directly and unequivocally the role played in spoilage by various bacterial groups and that it is no longer necessary to rely on indirect evidence.

Certain Physiological and Biochemical Changes in the Developing Tomato Fruit (Lycopersicon esculentum Mill.)

SUMMARYThe biosynthesis of nonvolatile compounds by tomato fruit parallels the growth rate of the fruit, regardless of varieties studied. Volatile reducing substances (VRS, mμ100 g), reducing sugars (percent), water‐soluble pectins (percent), and organic acids (mg/100 g) progressively increase in quantity with advancing maturity. Total titratable acidity (percent) and total pectic materials (percent) increased during the initial stages of maturation, but gradually decreased as the fruit ripened. Ascorbic acid (mg/100 g) increased with the maturity of fruit but declined slightly in the later (red and red‐ripe) stages of maturation. Concentrations of compounds (chlorophylls, mg/100 g; carotene and lycopene, mg/100 g) contributing to the coloration changed significantly as the fruit passed through various degrees of maturation. The pattern of physiological and chemical changes during the development of tomato fruit was nearly identical in both varieties studied. However, V. R. Moscow fruit contained higher amounts of pigments, reducing sugars, pectins, organic acids, ascorbic acid, and VRS than the fruit of Fireball variety, regardless of maturities studied.

Evaluation of volatile odoriferous components of saliva

The objectives of this investigation are to elucidate chemical reactions involved in odour production, to characterize the odour components, and to establish suitable chemical methods for the determination of odour intensity of saliva. It is felt that the knowledge gained from this study will contribute to a better understanding of the fundamental problems of mouth odour. A relationship has been found between the odour intensity and the volatile reducing substances (VRS) content of putrefied saliva. Fractionation of the VRS indicates that the odour components are primarily of acidic nature. Substrate and enzyme inhibition studies identified the malodourous composition as being volatile sulphur-containing compounds such as H 2S and mercaptans. Substrates (cysteine, reduced glutathione, peptones) which possess free sulphhydryl groups were found to be the most immediate sources of odour. Other sulphur-containing substrates as methionine, cystine, and oxidized glutathione also stimulated odour on prolonged incubation of saliva. Experimental evidence was obtained which suggests that certain inorganic salts, as thiosulphate, can be utilized for odour production by saliva. The described observations are contrary to the traditional belief that amines and ammonia are the most important sources of odour.

Studies on the Volatile Reducing Substances of Instant Tea

Studies on the Volatile Reducing Substances of Instant Tea