Acceptability of minimally processed and irradiated pineapple and watermelon among Brazilian consumers

This study aimed at evaluating the acceptance of MP watermelon and pineapple exposed to 1.0 and 2.5 kGy compared to non-irradiated samples. No significant differences were observed in liking between irradiated and non-irradiated samples, and also between doses of 1.0 and 2.5 kGy. Significant differences in sourness (pineapple) or sweetness (watermelon) and between intention of purchase of irradiated and non-irradiated fruits were not observed as well. Results showed that MP watermelon and pineapple could be irradiated with doses up to 2.5 kGy without significant changes in acceptability.     

The effect of gamma irradiation on physicochemical and microbiological quality of fresh pork loins

Radiation treatments were carried out under air on fresh pork loins at doses of 2, 4 and 8 kGy and the loins were evaluated for deamidation, solubility, sulphydryl content and surface hydrophobicity. Deamidation was significantly (P0.05) affected by the treatment with 98% deamidation at a dose of 8 kGy. No significant changes (P>0.05) were noted in sulphydryl content under the same conditions. The increase in deamidation was accompanied by a decrease in hydrophobicity and an increase in protein solubility. γ-Irradiation also reduced the number of microorganisms in the meat. Mesophiles were more resistant to the irradiation treatment than psychrotrophs and Pseudomonas.     

Chemical, sensory and microbiological changes of gamma irradiated coconut cream powder

A study was carried out to determine optimum decontamination dose for a locally manufactured coconut cream powder. Samples were gamma irradiated (0–15 kGy) and ageing process was achieved using GEER oven at 60 °C for 7 days, which is equivalent to one-year storage at room temperature. Iodine value (IV), ranging from 4.8 to 6.4, was not affected by radiation doses and storage, however peroxide value and thiobarbituric acid (TBA) generally increased with radiation doses. In most samples, peroxide value (meq/kg) reduced after storage, whilst the TBA (mg malonaldehyde/kg), indicator for product quality, slightly increased. The sensory evaluation conducted using 25 taste panellists indicated that scores on odour, creamy taste and overall acceptance for all irradiated samples at more than 5 kGy were significantly lower (P<0.05) than the control. However, the panellists could not detect any significant differences among the irradiation doses (P>0.05). All stored products were significantly different in colour, creamy taste, odour and overall acceptance (P<0.05) when compared to the non-stored non-irradiated control. Microbiological count of the samples prior to irradiation was in the range of 1×10²–1.7×10³ cfu/g with no detection of Salmonella sp. and Escherichia coli. No microbial colonies were detected after irradiation. Based on the TBA and overall sensory acceptance, gamma irradiation of 5 kGy was found to be the optimum dose and lower doses can be considered to decontaminate coconut cream powder.     

Effect of radiation processing on nutritional and sensory quality of minimally processed green gram and garden pea sprouts

In the present study, radiation processing of minimally processed green gram and garden pea sprouts was carried out at doses 1 and 2 kGy. The effect of this treatment on different quality parameters like vitamin C content, total carotenoids content, sensory quality, texture, and color was determined over a storage period of 12 days at two different temperatures, a 4 and 8 °C. It was observed that treatment of irradiation (1 and 2 kGy) and storage period did not have any significant effect on vitamin C content of control as well as irradiated sprout samples stored at 4 and 8 °C. Total carotenoids content of sprouts stored at 4, as well as at 8 °C, for 12 days remained almost unchanged after irradiation as well as during storage. Sensory evaluation studies showed that irradiation had no significant effect (p>0.05) on the ratings of any of the sensory attributes in green gram as well as garden pea sprouts and, thus, did not alter the overall acceptability of the irradiated sprouts. Textural studies revealed that there was no significant change (p>0.05) in the firmness of irradiated sprouts (1 and 2 kGy) as compared to control samples at both the temperatures. Storage period of 12 days also did not affect the firmness of sprouts significantly. Color measurement results indicated no drastic change in the color coordinates of the green gram samples except greenness of controls stored at both the temperatures, which showed insignificant decrease in the a^* values. Thus, the nutritional as well as sensory quality of minimally processed green gram and garden pea sprouts did not alter significantly after gamma irradiation with a dose of 1 and 2 kGy.     

Thermal behavior of different cocoa powder varieties and their physicochemical,phytochemical and microbiological characteristics

Four cocoa powder varieties processed in different European countries (Germany, Poland, Romania and Bulgaria) were subjected to physicochemical, phytochemical and microbiological analysis. The cocoa powders were extensively characterized by recording their pH and titratable acidity, respectively, the polyphenols and also the methylxantine derivatives content (theobromine and caffeine). The cocoa powders pH ranged between 5.37 and 8.23, while the titratable acidity was 3.2–4.3 miliequivalent (100 g)^?1 of cocoa powder. Their total polyphenols content ranged between 0.986?÷?2.003 g GAE/(100 g)^?1. The methylxanthine derivatives (theobromine and caffeine) were analyzed by the HPLC method and ranges of 0.992–1.174% for theobromine and 0.096–0.369% for caffeine were obtained. Thermal analysis (TG–DTA) combined with mass spectrometry (MS) elucidated the decomposition processes and the volatile substances (CO, CO₂, H₂O, NO, theobromine, caffeine). The thermal analysis revealed transformations in the cocoa powders composition: drying and water loss; decomposition of pectic polysaccharides; lipids, amino acids and proteins, crystalline phase transformations and carbonizations. The microbiological analysis tested the degree of preservation of the cocoa powders across time, specifically immediately after unwrapping and after 14 days.

     

Studies on some microbiological and chemical aspects of irradiated vanilla beans

Vanilla bean is a valuable food additive used in many branches of food industry as a source of natural vanillin. The influence of⁶⁰Co -radiation in the dose range of 5–50 kGy has been investigated on: (1) the survival of contaminating microflora, and (2) more important vanilla constituents like vanillin and sugars. It has been found that the main vanilla contamination is connected with mesophylic microorganisms in the amount of 8.4·10⁴/g. The dose of 15 kGy is sufficient for decontamination of commercial raw material. The samples under investigation on account of sensory properties and chemical composition were in agreement with country regulations. Doses up to 50 kGy do not cause undesirable changes in the content of sugars and vanillin, which has been confirmed by studies on model compounds.     

Gas chromatographic/mass spectrometric and microbiological analyses on irradiated chicken

Ionizing radiation is widely used as treatment technique for food preservation. It involves among others reduction of microbial contamination, disinfestations, sprout inhibition and extension of shelf life of food. However, the commercialization of irradiated food requires the availability of reliable methods to identify irradiated foodstuffs. In this paper, we present results on the application to irradiated chicken of this method, based on the detection, in muscle and skin samples, of the peaks of ions 98 Da and 112 Da, in a ratio approximately 4:1, typical of radiation induced 2-dodecylcyclobutanones (2-DCB). Aim of the work was also to study the time stability of the measured parameters in samples irradiated at 3 and 5 kGy, and to verify the efficacy of the treatment from a microbiological point of view. Our results show that, one month after irradiation at 3 kGy, the method is suitable using the skin but not the muscle, while the measured parameters are detectable in both samples irradiated at 5 kGy. The microbial population was substantially reduced even at 3 kGy.     

Nutritional,physiological, physicochemical and sensory stability of gamma irradiated Kimchi (Korean fermented vegetables)

Effects of gamma irradiation on nutritional, physiological, physicochemical and sensory properties of the Korean lactic acid fermented vegetable, Kimchi, were investigated. The composition of amino acids and organic acids in Kimchi were not influenced by gamma irradiation less than 10 kGy. Angiotensine converting enzyme inhibitory, xanthin oxidase inhibitory, electron donating and antimicrobial activity of Kimchi extract were stable up to 10 kGy. There were no significant changes in pH and texture at less than 10 kGy. Color values were influenced at 10 kGy of gamma irradiation, and resulted in the increase of L*- and reduction of a*-value. About 90% of panelists identified a sensory difference between non-irradiated and 10 kGy-irradiated sample, and Kimchi irradiated at 10 kGy had lower scores in acceptability than those of the control or irradiated at 2.5 and 5 kGy.     

Effect of low-dose γ-irradiation on the shelf life and quality characteristics of minimally processed potato cubes under modified atmosphere packaging

The processing conditions involving γ-irradiation for minimally processed potato cubes were optimized by response surface methodology. The effect of γ-irradiation dose (0–1.5 kGy), citric acid concentration (0–1.0%), KMS concentration (0–1.0%) and their complex interaction on L, a, b value, hardness and total sugar content were studied using a central composite rotatable design of experiments. The results showed that at the optimum conditions (γ-irradiation dose 1.0 kGy; citric acid concentration 0.33% and KMS concentration 0.55%) the L-value was ⩾48.50%, a-value ⩽0.95, b-value ⩽7.5, hardness ⩾100 N, sucrose concentration ⩽0.19% and sensory score ⩾6.0 at the end of the storage period of 4 weeks.     

Protein quality of irradiated Brazilian beans

Beans are a major source of dietary protein in Brazil. However, high losses due to insect infestation occur after each harvest. To combat these losses, radiation processing of beans offers promise as an alternative to chemical treatment, provided the nutritional quality of beans is not impaired by the radiation treatment. Conflicting results have been published about the effect of radiation on the biological value of legume proteins. Therefore, two varieties of Brazilian beans were studied: 1) Phaseolus vulgaris L., var. carioca and 2) Vigna unguiculata (L.) Walp, var. macaçar. The beans were irradiated with doses of 0, 0.5, 1.0, 2.5, 5.0 and 10 kGy. Since irradiated beans will be consumed after appropriate storage, the beans under study were stored for 6 months at ambient temperature. Protein quality was measured by a biological assay employing the nitrogen balance approach in weanling rats. The animals were fed with optimally cooked beans, which were the only source of protein (10%). Nitrogen contents of legumes, diets, animal urine and faeces were determined by Kjeldahl analysis. The indices for apparent protein quality: net protein utilisation, digestibility and biological value were not influenced by irradiation. Thus, radiation treatment of Brazilian beans offers considerable promise as an effective insect disinfection process, without impairing the biological quality of the valuable bean protein.     

Sensory quality, volatile compounds and color of pear juice treated with β-cyclodextrin

The effect of the addition of β-cyclodextrin (β-CD), the most used of natural CDs, on the pear juice quality was studied. Several properties of this fruit juice, such as color, odor and aroma have been evaluated in both the absence and presence of β-CD for the first time. A study of the aroma profile of pear juice showed that esters, aldehydes, alcohols and terpenes are the most important chemical families of volatile compounds present in this fruit juice. Furthermore, a trained sensory panel was used to quantify odor/aroma attributes of pear juices in both the presence and absence of increasing β-CD concentrations. The addition of β-CD at a concentration of 15 mM to pear juice significantly increased its global quality, color intensity and reduced its browning but without any significant decrease in aroma. For this reason, a concentration of 15 mM of this type of natural CD is recommended to be used in pear juice manufacturing.     

Organic bee pollen: botanical origin, nutritional value, bioactive compounds, antioxidant activity and microbiological quality

Organic bee pollen (BP, n = 22) harvested from the Douro International Natural Park (DINP, Portugal) was studied. Nine botanical families were found in the mixture of the samples. The water activity and pH ranged 0.21-0.37 and 4.3-5.2, respectively. The BP analyses averaged 67.7% carbohydrates, 21.8% crude protein, 5.2% crude fat and 2.9% ash. The energy ranged from 396.4 to 411.1 kcal/100 g. The principal fatty acid found was linolenic, followed by linoleic acid, palmitic acid and oleic acid. The phenolic and flavonoid contents varied from 12.9 to 19.8 mg of gallic acid equivalents/g of extract and from 4.5 to 7.1 mg of catechin equivalents/g of extract, respectively. The scavenger activity and β-carotene bleaching assays values (EC??) were 3.0 ± 0.7 mg/mL and 4.6 mg/mL ± 0.9 mg/mL, respectively. E. coli, sulphite-reducing Clostridia, Salmonella and S. aureus were not found. Since there are studies indicating appreciable differences among BPs from different regions, the full characterization of BP from diverse origins still appears to be a sound research priority in order to obtain reliable data about this beehive product.     

Changes in physicochemical and mechanical properties of electron-beam irradiated polypropylene syringes as a function of irradiation dose

In the present study, the effect of electron-beam irradiation on physicochemical and mechanical properties of polypropylene (PP) syringes was studied. Three irradiation doses (30, 60 and 120 kGy) were applied to all samples. Non-irradiated PP syringes were used as control samples. Electron-beam irradiation caused an increase in the degree of yellowness and in the extractable radiolysis products. A decrease in compression strength and extension at break was the result of electron-beam irradiation on mechanical properties of PP syringes. Minor differences were observed in FTIR spectra, mainly in the region of 1720 cm⁻¹, corresponding to the absorption of carbonyl compounds. Gas chromatography/mass spectrometry (GC/MS) analysis indicated the formation of a number of radiolysis compounds while a number of compounds initially present in non-irradiated syringes were destroyed by the irradiation. The degradation on polymer properties caused by electron-beam irradiation was less severe than that caused by gamma irradiation.     

Evaluation of low-dose irradiation on microbiological quality of white carrots and string beans

The minimally processed food provided the consumer with a product quality, safety and practicality. However, minimal processing of food does not reduce pathogenic population of microorganisms to safe levels. Ionizing radiation used in low doses is effective to maintain the quality of food, reducing the microbiological load but rather compromising the nutritional values and sensory property. The association of minimal processing with irradiation could improve the quality and safety of product. The purpose of this study was to evaluate the effectiveness of low-doses of ionizing radiation on the reduction of microorganisms in minimally processed foods. The results show that the ionizing radiation of minimally processed vegetables could decontaminate them without several changes in its properties.     

Application of chemometrically processed chemical and thermoanalytical data for quality control of soybean oils

The quality assessment of commercial soybean oils was evaluated on the basis of chemical and thermal analyses. The most substantial chemical parameters, viz. the density, refractive index and saponification, iodine and acid numbers were estimated. The thermal parameters were determined on the grounds of the TG and DTG curves. There are temperatures for the onset, end and successive mass losses. To find the relation between the chemical and thermal parameters, regression and principal component analyses were applied. The results of principal component analysis indicate that the TG and DTG techniques are at least in equal degree useful in defining the quality of soybean oils, as compared with the chemical analyses.     

Development, production and certification of microbiological reference materials

Since 1986 the National Institute of Public Health and Environmental Protection (RIVM) in the Netherlands has been developing and testing reference materials (RMs) for use in the field of water and food microbiology within the framework of the Measurements and Testing Programme (former BCR) of the European Union. The materials consist of gelatin capsules filled with artificially contaminated spray dried milk. Individual and collaborative studies on stability and homogeneity of the materials are described. The positive results obtained are followed by certification studies on certain reference materials. The results of two certification studies have now satisfactorily been completed, and certified values, related to the methods used, have been given for two certified reference materials (CRMs) containing the bacterial strains Salmonella typhimurium (5 cfp/capsule) and Enterococcus faecium (500 cfp, capsule), respectively. Two other RMs containing Bacillus cereus and Enterobacter cloacae will be certified by the end of 1994.     

大白菜、甘蓝和西兰花中锐劲特残留量气相色谱分析方法的研究

建立了大白菜、甘蓝和西兰花3种蔬菜中的锐劲特残留量分析方法。以乙腈为提取溶剂,使用弗罗里硅土SPE小柱净化,最后利用GC-ECD进行检测,仪器最小检测量为5×10-13g,最低检出浓度为0.0005 mg/kg。在大白菜中平均回收率为85.11%~89.81%,RSD为3.8%~6.8%;甘蓝中平均回收率为91.39%~102.92%,RSD为5.2%~8.3%;西兰花中平均回收率达到91.92%~101.64%,RSD为4.5%~6.8%。     

Electronic structure, physicochemical characteristics, and stability of polycyclobutadienes

The electron distributions, current distributions, enthalpies of formation, diamagnetic susceptibilities, electric polarizabilities, and the energies of the lowest singlet-singlet and singlet-triplet transitions for a series of polycyclobutadienes C_2n+2H₄ were calculated within the scope of the PPP method. It was shown that according to the energy and magnetic criteria the molecules of this series can be divided into three groups, the molecules of one of which are presumably stable. Donbass State Academy of Construction and Architecture. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 1, pp. 1–5, January–February, 1997.     

Synthesis, structure, and physicochemical properties of gel-forming dextran phosphates

Dextran phosphates with the degree of substitution of 0.29–1.09 with phosphoric acid groups and of 0.14–0.83 with carbamate groups were prepared in the orthophosphoric acid-urea system. The effect of the component ratio in the esterifying mixture, temperature, and pressure in the reaction zone on the structure and physicochemical properties of dextran phosphate hydrogels and on the gel fraction yield was examined.     

Synthesis and some physicochemical properties of antamanide, retroantamanide, and perhydroantamanide

Summary The synthesis of antamanide, retroantamanide, and perhydroantamanide has been effected. It has been shown that the inversion of the direction of acylation — the equilibrium interchange of the valine and alanine residues (retroantamanide) — lowers the stability of the complexes with sodium and potassium in ethanolic solutions, while the replacement of the phenyl groups by cyclohexyl groups has practically no effect on complex formation.M. M. Shemyakin Institute of the Chemistry of Natural Compounds, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 469–474, July–August, 1971.