Search results

The purpose of this paper is to analyze whether consumers can discriminate coffees in the same way as a professional coffee judge, a cupper, to assess the relevance of cuppers' evaluations for taste differences perceived by consumers.

In total, 23 samples sold in international stores as Tarrazú coffee were bought. A cupper evaluated these samples using the international cupping procedures for the quality attributes aroma, fragrance, body and acidity. Of the 23 samples, five were used in a triangle test carried out by a panel of 12 non‐expert consumers to determine if their discriminations matched the expert's judgment.

Results from the cupper gave a high variability of the coffees evaluated. The results of the consumer panel demonstrated that discrimination between coffees by consumers was predicted by acidity differences assessed by the cupper. The same held for body but not necessarily for fragrance and aroma.

The paper revealed that discrimination between the coffees by the consumer panel matched the coffee cupper's evaluation differences. The high consistency of the results obtained from the consumer panel underpins that the respondents did not have much difficulty in rating the coffees with the same scores as the professional coffee judge. Thus, differences in coffee quality, notably with respect to acidity, are important to consider in coffee production and marketing as consumers can perceive them and thus use this information when deciding whether or not to buy the product again.

This paper aims to investigate the effect of acidity on the morphology of archeological paper, especially in the presence of colors and whether natural pigments play a role in the process of degradation.

The morphological changes in the cellulosic fibers of the manuscripts because of acidity were investigated using environmental scanning electron microscope (ESEM). Ten historical samples were collected from different manuscripts suffering from acidity. X-ray diffraction was used to identify the inks and pigments that were used in some samples. Additionally, Fourier transform infrared microscopy was used to identify the binding medium.

The results confirmed that carbon ink, ultramarine, cinnabar and gold pigments were applied to some manuscripts with Arabic gum. As for ESEM investigation, the results proved that acidity badly affected the integrity of the cellulosic fibers resulting in their embrittlement. The micrographs showed differences in fiber degradation according to pH value. The presence of inks and pigments increased the degradation extent resulting from acidity.

This paper addresses a specific need to study the behavior of degradation in paper manuscripts, thus helping the conservators find solutions to the phenomenon.

Yoghurt consists of approximately 60 per cent of per capita dairy consumption of Iranian people. Iranian dairy factories use commercial starters which are expensive in yoghurt production. Moreover, yoghurt produced by these starters does not completely meet the taste of Iranian consumers. The aims of this study are to produce well qualified yoghurt from isolated native starters and to evaluate microbial, chemical and organoleptic characteristics of products.

The microflora of Iranian native yoghurts were isolated, purified and identified. The isolated strains were used as starter for the production of yoghurts. Sensory evaluation and measurement of pH, acidity and acetaldehyde content of the samples were carried out. Acidity, pH, acetaldehyde content, and microbial population of the best samples were measured during 21 days of cold storage. SPSS software was used for statistical analysis.

During the above mentioned storage period, acidity and acetaldehyde content increased significantly (p < 0.05). Significant decreases (p < 0.05) were observed in pH and microbial population. No significant difference in organoleptic characteristics (taste, smell and texture) were found after 21 days of cold storage.

Yoghurt production by native starter cultures instead of commercial ones is beneficial in respect of both economic and organoleptic aspects. The results indicate that the use of isolated native yoghurt starters in manufacturing yoghurt can be satisfactory and can also be extended to the production of yoghurt on an industrial scale.

Summary It has been noticed that during electrolysis of zinc from sulphate solutions in the presence of Germanium, the utilisation of current varies with the change of concentration of Ge in the electrolyte, and from the neutral electrolyte it decreases with the increase of current which passed through the electrolyte. Therefore dependencies of current utilisation on concentration of acid and concentration of Ge in the electrolyte have been investigated. It has been found the current utilisation decreases when the acidity increases, the decrease being also proportional to the increase of concentration of Ge. The activity of Ge is the more intensive with the higher the acidity. The cause of the fact that concentration of Ge in the electrolyte remains constant after a certain duration of electrolysis has been explained, as well as that the absolute value of this concentration depends only on the initial concentration of Ge. It has been stated that deposition of Ge on the cathode ceases (either in the form of metal or hydride) when the electrolyte has reached an acidity value of about 120 g/l H2SO4.

The goal of this paper is to model the activated carbon adsorption capacity of cadmium using a polynomial regression model. The properties that influence the removal of heavy metals by activated carbon must be taken into consideration in order to synthesize materials specific to the characteristics of the pollutant.

Multivariable analysis applications allow a comprehensive description of the relationship between activated carbon surface properties and heavy metal adsorption.

The authors use a second-grade polynomial regression model to determine the influence of porosity and surface acidity in cadmium adsorption by activated carbon.

The authors propose a statistic analysis to correlate the carbon properties with its cadmium adsorption capacity. Model coefficient analysis will give a better comprehension of the influence of activated carbon porosity and surface acidity of cadmium removal.

This paper sets out to focus on the utilization of the locally available raw material to develop an acceptable and high quality non‐alcoholic beverage in Nigeria.

Maize‐based non‐alcoholic beverages were produced from either plain maize powder or combinations of maize powder and mango or soybean flour. Plain and fruit or soy‐ fortified maize powders were analyzed using standard methods for chemical composition, while total solid, sediment height, pH, titratable acidity, storage stability and microbial load were determined on the formulated beverage products. Taste panel evaluation was conducted to evaluate the acceptability of the products.

While the protein, fat and ash contents of plain maize powder were 5.69, 5.95 and 0.35 per cent respectively, there was minimal enhancement with fruit addition. However, with 10 per cent soybean addition significant improvement over the unfortified sample in protein (14.62 per cent), fat (10.64 per cent) and ash (0.96 per cent) was obtained. Sediment height was found to be higher for beverage with sour water and least for soy‐fortified beverage. Titratable acidity of beverage samples was found to be 0.022, 0.018, 0.054 and 0.306 per cent (per cent lactic acid) for plain, fruit‐flavoured, soy‐fortified and soured beverages respectively. Variation in titratable acidity was observed depending on the product and storage condition. Sensory evaluation result for beverage prepared with sour water (0–100 per cent) revealed preference for soured beverage with 80 per cent sour water. Also, fruit‐flavoured sample ranked highest in preference followed closely by the plain beverage, while soy‐fortified sample was the least acceptable.

The paper has demonstrated the feasibility of developing acceptable beverage samples from sour water (a by‐product of Ogi usually regarded as waste) and combinations of either maize powder and mango or soybean flour.

The principles of acidity and basicity measurement are explained by describing colour‐indicator titration of aqueous solutions. Similar methods are used to determine neutralisation values of non‐aqueous solutions such as petroleum products, although electrometric titration is more suitable for dark‐coloured oils and used oils. The practical importance of neutralisation value tests is discussed, with particular reference to additive oils, turbine oils, gear lubricants and transformer oils.

Traditional fermented products can be adopted as probiotic carriers. This study was aimed at evaluating the potential of using Obushera, a traditional sorghum beverage from Uganda, as a carrier for Lactobacillus rhamnosus yoba.

Probiotic Obushera was produced by fermenting sorghum malt with Lb. rhamnosus yoba 2012 and Streptococcus thermophilus C106 at 30 °C and at room temperature (21°C-25 °C) for 24 h. Acidity, pH, total soluble solids and microbial counts were monitored. Consumer acceptability and purchase index of probiotic Obushera were compared to four commercial non-probiotic brands. Shelf stability of probiotic Obushera was determined by monitoring changes in pH, acidity, soluble solids, microbial counts and consumer acceptability during refrigerated storage.

Lactobacillus rhamnosus yoba 2012 multiplied and lowered the pH of Obushera from 5.3 to < 4.0 (p < 0.0001) whilst increasing acidity from 0.21 to 0.46 per cent (p < 0.0001) in 9 h at 30 °C. Consumer acceptability varied with Obushera brand (p < 0.0001). The overall acceptability score of probiotic Obushera (score of 6.4 = like slightly) was similar to that of the two most acceptable commercial brands (scores of 5.8 and 6.6). Acidity, pH and Lb. rhamnosus counts of probiotic Obushera varied within 0.6 per cent –1.05 per cent (p < 0.0001), 3.3–3.4 (p < 0.0001), and 8.2-9.2 log cfu/ml (p < 0.0001), respectively during two months of storage. The overall acceptability of probiotic Obushera (scores of 6.9-7.8) did not change significantly during storage (p = 0.185).

Traditional fermented foods such as Obushera can be adopted as carriers of probiotic microorganisms.

Use of commercial probiotic strains in traditional fermented foods is a novel approach that can be adopted to improve safety of traditional fermentations and health of consumers.

Visible and near infrared spectroscopy have been applied widely in fruits quality assessment especially on the measurement of soluble solids content (SSC) measured in ^oBrix and acidity measured in pH. Spectroscopy technique has been applied on three botanically different categories of fruits, that is: imported Californian table grape, Mandarin lime and star fruit. The purpose is to examine the ability of spectroscopy technique to quantify internal quality parameters with very narrow variability due to the characteristics of the raw material analyzed. This work also presents comparative study on peak wavelengths that can best be used to calibrate SSC and pH of different types of fruits.

The effective wavelengths chosen for calibration development are compared with those selected by other researchers in similar experiments. NIR wavelengths 910 nm (C−H band) and 950 nm (O−H band) are the most important wavelengths for the prediction of SSC for all examined fruits while wavelengths 922‐923 nm and 990‐995 nm for pH. Visible wavelength 605, 675 and 654 nm can efficiently improve the SSC and pH prediction for grape, lime and star fruit, respectively.

The best prediction for SSC has been achieved with R²=0.953 and RMSE=0.182 for grape, R²=0.918 and RMSE=0.109 for lime and R²=0.957 and RMSE=0.354 for star fruit. The best prediction for pH has been achieved with R²=0.763 and RMSE=0.110 for grape, R²=0.841 and RMSE=0.073 for lime and R²=0.862 and RMSE=0.261 for star fruit.

Currently, the spectroscopy research conducted for the measurement of fruits qualities is conducted through wide range spectrometer. However, the peak responses are only located at specific wavelengths. Hence, the selection of wavelengths related to SSC and pH will allow the design of low cost instruments for the prediction of these internal quality parameters.

The purpose of this paper is to develop a structural model of factors determining quality of juices and to indicate major variables that are significant for further product development.

Juices of apples, oranges, grapefruits, black currants and mixed fruits were subjected to testing in order to determine the qualitative structure of fruit juices. The following determinations were carried out in all fruit‐juice samples: total solids (Brix), Brix other than sucrose, total acidity, pH, vitamin C content, total sugars, direct‐reducing‐sugar content, saccharose content and volatile acidity. In addition, a sensory assessment in a 5‐grade score scale was carried out, covering the sensory characteristics of taste, flavour and colour. Based on the results of sensory analysis, a total sensory quality index (TSQI) was calculated.

Values of the linear correlation coefficient were calculated, and force and direction of the interdependence between the measured juice quality factors were determined. Analysis of major components was applied to develop a model of the structure of quality characteristics of fruit juices and to disclose latent variables. It enabled disclosure of four independent (orthogonal) areas, which determine the quality of fruit juices, and explain 70 per cent of the total juice quality area. They are represented by: total sugars, total solids (Brix), sensory quality and total acidity.

The research enabled identification of factors determining the fruit juice quality. It may prove very useful for R&D departments, as it informs an enterprise of which areas to focus their product development efforts on. Reducing the number of the major factors to four reduces costs and shortens the time necessary for product design and development.