Lovibond Scale Research Articles

Effect of bleaching with different clay on the final composition of post-fermentation corn oil with high content of β-sitosterol

Bleaching of oils is a stage of refining, and for post-fermentation corn oil, it is a novel issue intended to pretreat the corn oil for downstream refining processes. As a result of the completed research, which used a selection of available bleaching clays at 2 g/100g, post-fermentation corn oil with an improved quality was produced. The oil featured a reduced peroxide number and a lower content of carotenoid dyes. The oil after bleaching was found to have increased oxidation stability without any change discovered in the composition of fatty acids. From this research, it was observed that the 5σ-avenasterol levels were reduced, which affected the total phytosterol content and the reduction of oil colour on the Lovibond scale. The colour strength was considerably reduced by the bleaching process, to a level which varied with the specific bleaching clay. The content of the predominant β-sitosterol did not change significantly and remained at 700 mg/100 g. Optimum processing results were achieved by using the Tonsil 4120 AFF bleaching clay with an addition of activated carbon, and using the Supreme 112FF bleaching clay without activated carbon.

Physicochemical Properties of Virgin Coconut Oil Extracted from Different Coconut (Cocos nucifera L) Varieties

Virgin coconut oil (VCO) is a superior edible oil extracted from fresh coconut (Cocos nucifera L) kernel using mixed coconut varieties without considering the varietal effect. Therefore, this research focuses on the quality evaluation of VCO extracted from four types of coconut varieties, namely Sri lanka Tall×Tall (TT), a tall variety of Gon Thambili (GT), a tall variety of Ran Thambili (RT) and Philippines tall variety of San Ramon (SR). Mature coconuts from each variety were collected from the Bandirippuwa Estate of the Coconut Research Institute, Sri Lanka to extract VCO by cold press oil extraction method. The extractability of VCO from different varieties was investigated. Moisture, free fatty acid (FFA), fatty acid profile (gas chromatography), peroxide value (PV), color (Lovibond scale), total phenolic substances (Galic acid equivalent), antioxidant capacity (α,α-diphenyl-β-picrylhydrazyl, 0.1mM – DPPH method) and sun protection factor (SPF) of VCO extracted from each variety were analyzed. The experiment was conducted as a completely randomized design with three replicates. Data were analyzed using ANOVA using Tukey’s test by MINITAB 17. Oil extractability (58%-59%), FFA (0.04%-0.12%), color (0.43–0.93) and fatty acid profile of VCO did not show variation among varieties. A higher concentration of total phenolic substances was observed in GT (0.24±0.03mg GAE/100g) while antioxidant capacity (857.19±14.99mg/ml) and SPF (8.99±1.26) was rich in RT.

Colour of honey: can we trust the Pfund scale? – An alternative graphical tool covering the whole visible spectra

Honey is popular and versatile nutraceutical product, widely used as a sweetener. Its sensory properties, determined by the botanical origin, play a high role in consumers’ decision. Among these, colour is an important, often price-defining property. Colour evaluation of honey can be done by different ways, the most commonly known being the Pfund scale, but Lovibond scale or spectral analysis are used as well. The Pfund method provides a specific evaluation scale for honeys, however, this method is not able to detect slight differences and it also has some deficiencies.Our aim was to provide some examples proving the shortages of the present methodology for determination of honey colour and suggest a solution that could qualify as a possible standardized method. A template providing all the calculations (Pfund value, L*a*b*, C*ab, h°ab, ΔE*ab, ΔC* ab, Δh*ab, ΔH*ab, ΔL*, Δa*, Δb*) based on the UV-VIS transmission spectra, comparing the results of honey samples is attached. The experiment revealed the drawbacks of the Pfund scaling system. We provide an alternative analytical method that can deliver more details and information on honey colour and could overcome the deficiencies of the present protocols.

Effects of Combining Antioxidants on the Oxidative Stability of Refined, Bleached and Deodorized Palm Olein during Continuous Deep Frying of Potato Chips

In this study, the effect of a novel antioxidants composite system based on a synergetic composite between Tertiary butyl hydroquinone (TBHQ), Ascorbyl palmitate, citric acid, and Dimethicone have been evaluated against the classical common antioxidant system based on TBHQ at the highest permitted dose of 200 ppm during successive deep-frying cycles. Also, the shelf life of fried food and its sensory performance and oil absorption content o fried food were comparatively studied. The Novel antioxidant composite system is a synergetic blend of an artificial antioxidant, TBHQ and vitamin C palmitate( Ascorbyl palmitate) as natural identical antioxidants, an effective sequestrant which is Citric acid and poly dimethyl siloxane as an anti-foaming system to obtain the highest oxidative stability impact during deep frying. The frying processes were carried at 180 ᴼC for sliced potato chips for 8 successive frying cycles.Sensory evaluation of the fried potato has been conducted under accelerated storage conditions to determine the effect of the oil oxidative stability on the shelf life of fried food. The oxidative degradation of the oil was evaluated by measuring different oxidation and degradation parameters for their respective peroxide value ( PV), free fatty acid( FFA %), the content of conjugated dienes, P-anisidine value,( p-A.V), induction period (IP), and Lovibond color. The (%) of oil absorption in the potato chips was also measured. The sensory evaluation has been done for fried foods to evaluate the crunchiness and likability of obtained french fries. Results revealed that the jump in primary & secondary oxidation parameters as PV and p- A.V.of palm olein after 8 successive frying cycles was very limited for the antioxidant composite system I by only 1.842± 0.1 meq O2/ kg in PV and by 6.2315±0.45 for p-A.V. Same for FFA, the jump was limited for the antioxidant composite system I for only 0.084+/-0.005 as well. However, the final PV, FFA after the 8 frying cycles are still within the Codex and local Egyptian regulation limits the edible oil human usage. Same for other quality parameters like color jump was limited to 3.4 Red jumps on Lovi bond scale for composite I. Study proofed that palm olein fortified with 650 ppm of the antioxidant composite (I) consists of TBHQ, Ascorbyl palmitate, citric acid, and polydimethylsiloxane at the specified synergistic ratios gives outstanding stability to refined Palm olein during the successive deep frying up to 8 successive frying cycles. It also achieved less oil absorption for french fries by about 3.5% less than the same oil fortified with 200 ppm TBHQ, which is the highest permitted dose of this strong antioxidant. (P≤0.05). Furthermore, sensory evaluation of the fried potatoes has been improved with the novel antioxidant system compared to theclassical TBHQ system.

Comparative Analysis of the Physicochemical Characteristics, Phytochemical Components and Fatty Acid Profile of Avocado Pear (Persea Americana L) Pulp and Seed Oil

The physiochemical properties, phytochemical content, and fatty acid profile of Avocado pear (Persea americana) pulp and seeds oils were investigated. The pulp oil was extracted using the hot water flotation method while the seed oil was extracted by the soxhlet extraction method. Extracted oils were analyzed. The pulp oil was emerald green while the seed oil was brownish red in colour. Pulp oil has significantly higher blue (27B) on Lovibond scale. The oil yield, smoke point and flash point of the pulp oil were 28.26%, 171.00 °C and 201.67 °C respectively. Which were higher than 13.64%, 100.00 and 130.66 °C seen in the seed oil. Iodine value, FFA, peroxide value and saponification value of the pulp oil were respectively 50.70 g/100 g, 0.53%, 1.10 mEq/kg and 218.66 mgKOH/g while those of the seed oil were 40.68 g/100 g, 2.85%, 2.16 mEq/kg and 198.31 mgKOH/g respectively. Saponins, alkaloid, phenol, tannin, and oxalate content of the seed oil were significantly higher than those of the pulp oil, with respective values of 12.23, 1.06, 5.06, 3.05 and 10.07 mg/100 g. Flavonoid was however higher in the pulp oil, at 6.20 mg/100 g. avocado pulp oil contained 43.23% oleic acid, 19.78% linoleic acid. It contains only 35.31% total saturated fatty acids. The seed oil was shown to contain 55% palmitic acid, as the predominant saturated fatty acid and contained a total of 69% saturated fatty acids. It is recommended that avocado seed oil be refined before use for culinary purposes.

Adolescent mental health and activities in the period of social isolation caused by the COVID-19 pandemic.

The aim of the study was to investigate the relationship between the forms of youth activity (in a virtual environment and in the real world) and their mental health in the period of forced social isolation related to the COVID-19 pandemic. The findings presented here are part of a larger international project (research-all.org). The subjects were students of primary and secondary schools in Kraków (N = 455), aged 11 to 18 (M = 15.38, SD = 2.10). The instruments used in this study were: the MHC-SF Karaś, Cieciuch and Keyes wellbeing scale, the Connor-Davidson CD-RSC resilience scale, and the DASS-21 Lovibond scale designed to measure depression, anxiety and stress. The participants also reported the amount of time they spent on eight types of activity (online and offline) during and before social isolation. Correlation analysis showed that the more time students spend actively in a virtual environment, the higher the level of depression (r = 0.27; p < 0.001), anxiety (r = 0.25; p < 0.001), stress (r = 0.25; p < 0.001). The duration of online activity is also negatively correlated with psychological well-being (r = -0.13; p = 0.013), emotional well-being (r = -0.15; p = 0.003) and social well-being (r = -0.12; p = 0.026). Well-being increases with a higher number of activities that are not mediated by a screen medium (r = 0.17; p = 0.001). Social isolation resulted in an increase in online activity both in education and in the social life of young people. The results obtained indicate the intensification of negative affectivity in adolescents who spend more time in the online environments. Moreover, the protective role of non-Internet physical and social activities for the mental health of young people has been demonstrated.

A Novel Method for Measuring the Color of Edible Oil on the Lovibond Scale Based on Spectral Detection and Convolutional Neural Network

Abstract. A fast, high-precision method for measuring the color of edible oil on the Lovibond scale was developed and validated. It involves two components: spectral detection and data processing. The former was used for measuring the edible oil’s transmission spectrum in the visible range. The latter included a logarithmic method and a convolutional neural network (CNN) for calculating the color value from the transmission spectrum. The logarithmic method converted the multiplicative combination of spectra to an additive combination, which greatly improved the performance. A CNN with three convolutional layers was developed using Tensorflow. Validation tests of the method using ten different oil types showed a maximum error of 0.5, average error of 0.32, and error variance of 0.04. Thus, the proposed method can meet the needs of the edible oil industry, and it has great application potential. Keywords: CNN, Color of edible oil, Convolutional neural network, Lovibond scale, Spectral detection.

Fatty acids characterization, oxidative perspectives and consumer acceptability of oil extracted from pre-treated chia (Salvia hispanica L.) seeds

BackgroundChia (Salvia hispanica L.) seeds have been described as a good source of lipids, protein, dietary fiber, polyphenolic compounds and omega-3 polyunsaturated fatty acids. The consumption of chia seed oil helps to improve biological markers related to metabolic syndrome diseases. The oil yield and fatty acids composition of chia oil is affected by several factors such as pre-treatment method and size reduction practices. Therefore, the main mandate of present investigate was to study the effect of different seed pre-treatments on yield, fatty acids composition and sensory acceptability of chia oil at different storage intervals and conditions.MethodsRaw chia seeds were characterized for proximate composition. Raw chia seeds after milling were passed through sieves to obtain different particle size fractions (coarse, seed particle size ≥ 10 mm; medium, seed particle size ≥ 5 mm; fine, seed particle size ≤ 5 mm). Heat pre-treatment of chia seeds included the water boiling (100 C°, 5 min), microwave roasting (900 W, 2450 MHz, 2.5 min), oven drying (105 ± 5 °C, 1 h) and autoclaving (121 °C, 15 lbs, 15 min) process. Extracted oil from pre-treated chia seeds were stored in Tin cans at 25 ± 2 °C and 4 ± 1 °C for 60–days and examined for physical (color, melting point, refractive index), oxidative (iodine value, peroxide value, free fatty acids), fatty acids (palmitic, stearic, oleic, linoleic, α-linolenic) composition and sensory (appearance, flavor, overall acceptability) parameters, respectively.ResultsThe proximal composition of chia seeds consisted of 6.16 ± 0.24 % moisture, 34.84 ± 0.62 % oil, 18.21 ± 0.45 % protein, 4.16 ± 0.37 % ash, 23.12 ± 0.29 % fiber, and 14.18 ± 0.23 % nitrogen contents. The oil yield as a result of seed pre-treatments was found in the range of 3.43 ± 0.22 % (water boiled samples) to 32.18 ± 0.34 % (autoclaved samples). The oil samples at day 0 indicated the maximum color (R and Y Lovibond scale) value for oven drying while at storage day 60 (25 ± 2 °C), the highest color value was found for autoclave pre-treatment. The slightly increasing trend of color values for all treatments was observed during the storage period. The lowest iodine value (182.83 ± 1.18 g/100 g at storage day 0 & 173.49 ± 1.21 g/100 g at storage day 60, 25 ± 2 °C) was calculated for autoclaved samples while the maximum iodine value (193.42 ± 1.14 g/100 g at storage day 0 & 190.36 ± 1.17 g/100 g at storage day 60, 25 ± 2 °C) was recorded for raw chia samples. The significant increasing trend for all treatments was observed in case of peroxide value and free fatty acids production during storage. Maximum decrease in linoleic (35 %) and α-linolenic (18 %) fatty acids was observed in autoclaved samples. The oil from pre-treated seed samples obtained decreasing scores for sensory parameters throughout the storage period at different conditions.ConclusionsAs a result, chia seeds are an important source of lipids and essential fatty acids. The water boiling and high temperature processing of chia seeds provides instability to lipids during storage at room temperature. However, detailed investigation is required on the processing performance and storage stability of food products supplemented with pre-treated chia seeds and furthers their effect on biological system.

A versatile apparatus for the bench scale bleaching and deodorsation of vegetable oils

A versatile isothermal glass apparatus provided with sintered glass on the bottom was designed for the bench scale adsorptive bleaching and deodorisation of vegetable oils. The stream of argon bubbles agitated the sample in both cases and protected the vegetable oil effectively against undesirable autoxidation and photooxygenation changes. However, a variable concentration of hexanal (27-30 μmol/kg) was always present in half-refined oils due to the heterolytic fragmentation of alkyl hydroperoxides. The colour on the Lovibond scale and the content of phosphorus (< 5 mg/kg) were efficiently decreased during the laboratory bleaching of rapeseed oil. It was found out that the adapted glass apparatus connected with a vacuum pump (1 hPa, a stream of argon gas instead of stripping steam) was able to reduce the content of carbonyl compounds below detectable concentration at 220-240°C. Furthermore, the extent of minor geometrical and positional isomerisation reactions was negligible (0.035-0.130 wt%). The results of the bench scale bleaching and deodorisation experiments were completely comparable with the industrial equipment under reduced pressure of the air.

Experimental investigation of processing parameters and effects of degumming, neutralization and bleaching on lampante virgin olive oil's quality

The refining of crude oil is a purification process which aims to yield a high amount of triglycerides and to produce an acceptable refined oil quality. This work focuses on two topics: (1) the comparison of adsorption performance of four clays having different activation levels (Ads1, Ads2, Ads3, and Ads4) and (2) the identification of the effective factors using a fractional factorial design method of lampante virgin olive oil refining processes involving degumming, neutralization, and bleaching. The effects of the phosphoric acid concentration, ratio (acid/oil), degumming contact time, neutralizing agent excess, earth clay dosage, contact time and temperature of bleaching step were investigated through the determination of residual phospholipids content, free fatty acid percentage, oxidative stability, color, and trans fatty acids content.Based on adsorption isotherms, Ads1 is selected as the adequate clay contributing to color reduction with low formation of oxidation products. The results of a 2III7−4 model showed that the strength and the amount of phosphoric acid, and the bleaching parameters were the principal factors that controlled bleached oil quality. Residual phospholipids and acidity decreased as degumming agent increased. Additionally, the bleaching parameters were found to significantly affect the lovibond scale and oxidative stability.

In-line measurement of sunflower oil color in the Lovibond scale using a low-cost robust device

Determination of color in oil is an important measurement to predict quality and acceptability of edible oil. The aim of this study was to develop and optimize a fast, inexpensive, noninvasive and nondestructive in-line method for determination and control of color in sunflower oil. Based on visible and near-infrared light analysis, the in-line measurements of oil in the Lovibond scale were performed in an oil stream of 30m3/h and verified by means of visual and automatic colorimeters.

Analysing a method for small and medium sized companies to rate oil quality during immersion frying

This work studied the deterioration of commercial Frytol oil in controlled frying conditions using the anisidine index (AI) as standard evaluation method. The effect of temperature and time was studied at 170°C for up to 10 hours and at 200°C for up to 6 hours in the presence of factors which speeded up oil deterioration: 1% and 8% water based on the mass of oil and non-lipid material, 1% and 6% based on the mass of oil. Air flow rate was kept constant at 25 L h-1. The relationship between AI, colour and viscosity was studied to evaluate the technical viability of measuring these variables as a function of time to be used as a method for rating oil deterioration by small and medium sized enterprises (SME). Oil deterioration was higher and faster at maximum study interval values for each experimental factor, although only the effect of temperature was significant (p&lt;0.05). Red and yellow on the Lovibond scale were weakly related (AI R2=0.558 and R2=0.526, respectively), colour depending on frying temperature. Viscosity measured at 30°C had the highest coefficient of determination (R2=0.809) and was independent of frying temperature. Viscosity is thus a variable which can be used for determining frying oil deterioration in SME as a consequence of a significant change from 10 cP to 45 cP which is closer to frying oil deterioration limit (AI 156). It can facilitate determination and lower associated costs, there-by improving product quality and customer confidence in them.

PROPOSED REVISION OF THE LOVIBOND “52 SERIES” OF GLASS SLIDES FOR THE MEASUREMENT OF THE COLOUR OF WORTS AND BEERS

The Lovibond “52 Series” slides for the measurement of the colour of beers, malts and caramels have been highly successful in the past, but the series was chosen so early in the development of the science of colour measurement that it suffers from three serious defects—irregular colour proportions, irregular units of colour, and insufficiency of red in the higher colours. Tests have been made to establish (a) the curve of colour proportions; (b) the most desirable size of colour unit; (c) the desirable limits for the range of units; (d) the most desirable method of comparison between slides and solutions; (e) the most desirable source of illumination. As a result, recommendations are made relating to a revised Lovibond scale and to the way in which it should be used. The process employed in this standardization would appear to be applicable to the development of glass slides for colour measurement in other fields, e.g. oils or shellacs.

Sesame oil. II. Some chemical and physical properties of the oils from different varieties of sesame seed

SummaryFour varieties of sesame seed, grown in South Carolina, Nebraska, and Nicaragua, were solvent extracted in a pilot‐plant and the oils examined with respect to their physical and chemical characteristics. Only slight variations were found in these constants and in the composition of the oils.The oils were refined, bleached, hydrogenated to shortening consistency, and deodorized. The refining losses were low (1.4% to 4.7%) and the bleach colors light (1–3 yellow/0.4–0.6 red, Lovibond scale). Changes in composition and in values of the refractive index and plasticity during hydrogenation were similar to those reported for other oils of similar characteristics. The hydrogenated oils reached a shortening consistency at an iodine value of about 69. A.O.M. stability values for the hydrogenated oils were high.The data presented indicate that conventional methods of processing sesame oil can be applied with good results. Changes in constants and fatty acid composition during hydrogenation are essentially similar to those occurring in other vegetable oils, such as cottonseed or peanut oils.

Note on the spectrophotometric grading of vegetable oilson the N″ Lovibond scale

On the basis of data published by McNicholas, it is shown that there is no significant correlation between the lightness or darkness of an oil and the Lovibond grade assigned to the oil by the practical color grader. The Lovibond color grade of a vegetable oil may therefore be computed from its spectral transmittance by colorimetric methods without taking into account the luminous transmittance of the oil. This method of grading might serve to settle disputes among the oil chemists as to the correct Lovibond grade of an oil.

Photoelectric color measurements

Precision color measurements of oils, fats, waxes, etc. can be made with a Photoelectric Spectrophotometer, and their absorption or reflection determined with a degree of exactness not possible with any visual method. Oils of similar chemical constitution, although widely different in color, give similar spectral absorption curves. Oils of dissimilar chemical constitution, although alike when measured on the Lovibond scale, give dissimilar spectral absorption curves. This photo-electric method of measuring color may enable the oil chemist to make use of a method of color measurement that will disclose fundamental data.

Color sensitivity

This paper reports primarily upon tests of the color sense of about thirty men who have had large experience in the color grading of vegetable oils in terms of Lovibond glasses, nearly all of these men being members of the American Oil Chemists’ Society. Similar tests on five other observers are also included for comparison. All of the oil chemists were first tested by the Stilling Chart test, but the results by this test (although reported) are not the principal matter of interest. This test was regarded merely as preliminary, serving to discover any gross abnormality of color sense. The tests of specific interest relate to the observer's ability to report correctly very small differences in Lovibond red at 35 yellow 7.6 red on the Lovibond scale, brightness diffences being eliminated so that the judgment depends, in effect, entirely upon the observer's sensibility to difference in dominant wave length at equal brightness. The subject's ability in this regard was tested by the well known psycho-physical method of “right and wrong answers.” The results for each observer are expressed so as to show the probability of his perceiving correctly given small differences in Lovibond red, under certain specified conditions. The chief results may be summarized as follows: A difference of 0.1 red at 35 yellow 7.6 red is perceivedwith certainty by only very few exceptional observers. However, this difference is perceptible in the sense that its presence does affect the observer's judgmentin the average, although he is very doubtful of the reality of such a difference. The perceptibility of a difference amounting to 0.27 red is notably higher; but even this difference is not perceivedwith certainty by all normal observers. About two-thirds of the total number of oil chemists tested perceive a difference of 0.3 red at 35 yellow 7.6 red with practical certainty. Although they have not been tested at the small difference of 0.1 red, it appears likely that about one-third of the chemists already tested could detect this difference with practical certainty if put to the test. Four of the chemists tested appear to be unable to detect with certainty differences as great as 0.5 red. One proved to be very uncertain about differences as great as 10 unit. It is emphasized that these results are to be regarded as preliminary, and the following recommendations are made: The tests should be repeated in a more systematic way and under standard constant artificial daylight illumination, including the present observers and all other members of the Society who are engaged in the color grading of oils. For each observer the tests should be made for each of the following red differences in the order given: 0.5, 0.3, 0.2, 0.1. When the data so obtained are available, the Society should, in the light of these data, set a standard of performance for these to be charged with the duty of color grading of oil. Incidentally, these tests have shown that the normal observer's sensibility to difference in wave length is much greater than has been believed heretofore. Good observers can detect with certainty a difference of wave length as small as 0.1 millimicron for yellow light. This is of the order of one-fifth or one-tenth of what has been given as the “least perceptible difference” by previous authorities. This aspect of these data has been discussed in a paper communicated to the Optical Society of America at its meeting, October, 1927 (abstract to appear in the “Journal of the Optical Society of America,” vol. 16, p. 117; February, 1928).

A new type of color-comparator

A convenient form of instrument has been devised for comparing the color of cottonseed oils with glasses of the Lovibond scale. In this apparatus each color must be made up by a combination of the same color glasses, one chemist cannot use a single 8.5 red glass and another a 5, a 3, and a 0.5 glass to get the 8.5 match, all are forced to use an 8 and a 0.5 red, superimposed for this 8.5 reading. The glasses are protected from dirt and scratches, and are easily revolved into the optical field by the turning of external nurled wheels. The total color, yellow + red, when a match is made, is indicated in a straight vertical line upon four concentric dials, thus diminishing the chances for error in recording the glasses used. A uniform light source, practically normal daylight, is provided in the instruments which will eliminate lack of agreement between different laboratories due to the use of various kinds of illumination. The author wishes to express his indebtedness to Mr. P. F. Ballenger formerly Chief Engineer of the Southern Cotton Oil Co., for his assistance in solving the mechanical difficulties incident to the building of this device, for without his help it would be merely a chemist contraption instead of a finished instrument.