Deterioration of β-carotene in certain hydrogenated fats. III.—Factors affecting the rate at which green discoloration occurs

The influence of a variety of additives and thermal treatments upon the rate at which green discoloration develops in β-carotene-hydrogenated fat systems is reported. The observed effects are discussed in relation to the hypothesis that the colour change is associated with the production of β-carotene epoxides from the oxidation of β-carotene by peroxy acids which are formed by the interaction of aldehydoglycerides with dissolved oxygen. Possible methods which might be employed in avoiding the incidence of the discoloration include suitable choice of oil, the use of certain additives, notably commercial lecithin (for food uses), adequate ‘tempering’ of the finished fat, and care in the use of cool (and cold) storage.     

Deterioration of β-carotene in certain hydrogenated fats. II.—Products of β-carotene deterioration and nature of the green pigment

The non-saponifiable fraction from a sample of β-carotene-hardened palm kernel oil which had developed a green discoloration has been examined. A number of β-carotene oxidation products were found and these included a number of β-carotene epoxide derivatives. A compound thought to be β-apo-3-carotenal was also found, but the apo-2- and apo-4-carotenals were not present in more than trace amounts. A major component was similar to, but not identical with, mutatochrome (β-carotene 5,8-epoxide). It is suggested that the green discoloration of the carotenised fat was due to oxidation of β-carotene to epoxide derivatives by traces of peroxyacids and the conversion of these epoxides into green-blue ionised forms by the action of an acidic material present in the fat.     

Extraction of β-carotene from orange peels

Extraction of β-carotene from orange peels and its nutritional evaluation through feeding study were carried out to compare the bioavailability of the extractable β-carotene with that of synthetic β-carotene. The highest yield of extractable β-carotene was recovered using a mixture of acetone and hexane (1 : 1 v/v) as a solvent in a ratio of 15 : 1 (solvent/sample) and an extraction time of 15 minutes. Growth of rats fed a diet containing β-carotene extracted from orange peels was normal and their weight gain during feeding period was real. In addition, bioavailability of the extractable β-carotene was higher than that of synthetic β-carotene, as a result of the presence of extra oils in the diet that contained β-carotene extracted from orange peels. Finally, the economical advantage can be reached by extracting β-carotene from orange peels. The bioavailability of this extractable β-carotene was high enough to compete with that of commercial synthetic β-carotene. So, it can be strongly recommended to produce such product in a large scale.     

β-carotene content in sweet potato varieties from China and the effect of preparation on β-carotene retention in the Yanshu No. 5

To compare the β-carotene contents in different Chinese sweet potato (SP) varieties and to choose a variety of SP rich in β-carotene for the study of the effect of processing methods on β-carotene retention, β-carotene in thirteen varieties of sweet potato from China was measured by HPLC. The results showed that β-carotene contents were significantly correlated with SP flesh colours, with the orange-red fleshed SP varieties being higher in β-carotene.β-carotene contents in SP were affected by many factors, and this was demonstrated using the variety of Yanshu No.5, showing that the β-carotene contents in SP grown in different farming sites in the same area ranged from 53.2 to 84.3 mg kg^− 1 fresh weight. Moreover, β-carotene distributes unevenly in one SP root, with highest concentrations in the core. The β-carotene content was positively related to the root size.Five processing methods including boiling, steaming, microwave cooking, frying, and post steam-drying were simulated in the study to check their effects on the true retention of β-carotene in SP. Compared to boiling, steaming resulted in much more loss of β-carotene and microwave cooking resulted in the biggest loss of β-carotene among the five processing methods.

Industrial relevance

Orange-fleshed sweet potato can be prepared for sale and consumption, using methods that protect the β-carotene content. This can aid in promoting sweet potato as a staple food as well as a snack food for supplying vitamin A for both rural and urban populations. Prepared orange-fleshed sweet potato can contribute to alleviating vitamin A deficiency in China as well as other low-income countries.     

Effect of blanching,drying, freezing and storage on degradation of β-carotene in different fruits

Since biologically active carotenoids play a significant role in metabolism and because of the fact that its stability can be affected by various factors decomposition degree of β-carotene of various kinds of fruits after drying, freezing, blanching as well as after drying and freezing of blanched fruits has been researched in order to prolong their consumption time-limit. The β-carotene content was determined by means of the spectrophotometric method measuring adsorbance intensity at 450 nm. The results of investigation reveal that the decomposition degree of β-carotene increases significantly with storage time. Depending on the kind of fruits, treatment and storage time it ranged from 6.10% to 68.74%. No significant differences have been found after a longer storage between blanched and non-blanched fruits, either dried or frozen.     

Pink discoloration in canned pears I.—Role of tin in pigment formation

The major pigment in discoloured canned pears is identified as a purple-pink insoluble tin-anthocyanin complex from the effect of reagents for anthocyanins on the spectra of solid and syrup fractions of the product. This characterisation is supported by significant correlations between the intensity of reflected colour and the insoluble tin content of the solid fraction. It is suggested that formation of a tin complex is essential for the occurrence of pink discolorations in canned pears, and experiments are described designed to vary the intensity of discoloration by modifying the conditions controlling complex formation.     

Effect of β-carotene on vitamin A light stability in fortified milk

The effect of incorporation of β-carotene into the carrier system on the light stability of all-trans retinyl palmitate in fortified skim milk was investigated. Skim milk was fortified with all-trans retinyl palmitate using corn oil with and without added β-carotene as the vitamin carrier. Two levels of β-carotene were used, one similar to, the other half the concentration of vitamin A in the carrier system. After homogenization and pasteurization, fortified milk samples were exposed to fluorescent light (1614 lx) at 4°C in glass tubes.

Less light degradation of all-trans retinyl palmitate occurred in samples containing added β-carotene in the carrier systems compared to samples without added β-carotene. The β-carotene content of fortified milk samples showed only a slight decrease over the four-day period of exposure.     

Comparing effects of α‐ vs. β‐chitosan coating and emulsion coatings on egg quality during room temperature storage

Effects of α‐ and β‐chitosan (CH), soybean oil (SO) and their emulsions (CH:SO = 2:3) as coating materials on selected internal quality and sensory properties of eggs were evaluated during 5 weeks storage at 25 °C. After 3 weeks of storage, α‐ and β‐CH‐coated eggs changed to B grade, while SO‐ and emulsion‐coated eggs preserved grade A quality. Weight loss of eggs coated with SO and CH:SO emulsions was <2.0% vs. 5.3–5.8% for noncoated and CH‐coated eggs after 5 weeks of storage. β‐CH (0.9%) maintained lower weight loss of eggs than α‐CH (1.2%) only at 1‐week storage. Albumen pH of eggs coated with SO and CH:SO emulsions decreased progressively throughout storage. Eggs coated with β‐CH:SO emulsion and SO were significantly glossier than noncoated eggs. Consumers indicated positive purchase intent (69.17–76.67%) for all coated eggs. Overall, α‐CH:SO and β‐CH:SO emulsions extended egg shelf life by at least 3 weeks during room temperature storage.     

Sulphite mediated destruction of β-carotene: The partial characterisation of reaction products

Sulphite species will catalyse the destruction of β-carotene in homogeneous solution at pH 5·7 in the presence of Mn²⁺, oxygen and glycine. The products are highly oxygenated, containing from 10 to 15 oxygen atoms per β-carotene molecule. There is no evidence of extensive fragmentation or polymerisation of the carotenoid. The products appear to be widely hydrogen bonded and retain some conjugation of double bonds.     

Natural skin coating of the apple and its influence on scald in storage III.—α-farnesene

In a study of apple fruits grown under English conditions it was found that at the time of the respiratory climacteric the concentration of α-farnesene in the waxy skin coating began to increase rapidly from a low level and at 12° reached a peak after about 30 days. in the relative amounts of farnesene produced there was little to distinguish the scald-resistant from the scald-sensitive apple variety. Under the various conditions of low-temperature storage in use, it was found that the farnesene content of the skin was most influenced by the nature of the atmosphere, whether air or 8% CO₂, white the farnesene content of the waxy skin coating was more responsive to delay at room temperature before storage, diphenylamine treatment or wrapping in oiled wraps. The results are discussed in relation to the theory that farnesene is a chemical factor in the induction of superficial scald.     

Freeze-dried turkey muscle I.—Changes in nitrogenous compounds and lipids of dehydrated turkey during storage

Changes in proteins and lipids were followed during the storage of freeze-dried turkey breast muscle in air and in nitrogen. Oxidation of sulphydryl groups accounted for part of the oxygen uptake of air-stored samples, and was accompanied by a decrease in soluble nitrogen greater than in controls stored in nitrogen. The major deteriorative process at low moisture content was a type of ‘lipid’ browning reaction which was dependent on oxygen and caused discoloration and objectionable odours. Autoxidation of lipids catalysed by haem pigments and resulting in rancid flavours was not a major deteriorative process in freeze-dried turkey muscle. Lipid hydrolysis occurred at water contents of 8·2 and 5·4% but not at 0·8%.     

α 1,4 — α 1,6 Glucopolysaccharides Contained in Developing Maize Kernels

Corn grains with different filling times were fractionated in order to obtain their α 1,4 — α 1,6 glucopolysaccharide composition and structure. Sugary, waxy, flint and several hybrids were the varieties analyzed. There is an increase in the total content of polysaccharides, as the grain is completed. But, no differences in composition and structure were detected between the first sample analyzed (15th day after pollination) and the last one, which corresponds to the complete grain filling period. The methodology developed by us, allowed us to observe that the introduction of su character on the hybrids (F x S and S x F) has influence on the final polysaccharide structure. Also, in the F x W hybridα 1,4 — α 1,6 glucans, their structural characteristics were different from those of F or W pure.     

Precipitation of β-carotene microparticles from SEDS technique using supercritical CO2

This work investigates the application of the Solution-Enhanced Dispersion by supercritical fluids technique for the precipitation of β-carotene. The effect of pressure (8.0–12.0 MPa), temperature (293–313 K) anti-solvent flow rate (20–40 mL/min), solution flow rate (1–4 mL/min) and concentration of β-carotene in the dichloromethane solution (4 and 8 mg/mL) on the precipitation yield, particle morphology and particle size and size distribution was examined. Precipitated powders presented mean particle size varying from 3.2 μm to 96.8 μm with morphology of β-carotene microparticles changing from plate-like to leaf-like particles. The statistical analysis of the experimental results revealed that pressure, organic solution concentration and CO₂ flow rate had a significant effect on particle size. The precipitation yield was observed to be within the range of 71–94% and was statistically influenced by system temperature and pressure, and anti-solvent flow rate.     

Effect of gums on viability and β‐galactosidase activity of Lactobacillus spp. in milk drink during refrigerated storage

The viability and β‐galactosidase activity of four Lactobacillus strains in milk drink containing gums during 28 days of refrigerated storage at 4 °C were assessed. The population of Lactobacillus rhamnosus GGB101 and Lactobacillus rhamnosus GGB103 were maintained, whereas the population of Lactobacillus reuteri DSM20016 and Lactobacillus reuteri SD2112 significantly decreased. The recommended level of 6 log CFU g^?1 was exceeded for all tested trains throughout storage. The highest viable number of Lactobacillus rhamnosus GGB103 (8.76 ± 0.03 log CFU mL^?1) was obtained in the product containing carrageenan–maltodextrin. The addition of guar–locust bean–carrageenan led to 20‐fold increase in the level of β‐galactosidase activity for L. rhamnosus GGB101 (1208 ± 2.12 Miller units mL^?1) compared to the control (61 ± 2.83 Miller units mL^?1). Our results suggested that gums could be added to milk to improve viability and enhance β‐galactosidase activity of Lactobacillus.     

Lesser known Nigerian edible oils and fats. I.—Characteristics of melon seed oils

Some of the characteristics of a melon seed oil, which is shown to be of the semi-drying type containing mainly linoleic and oleic acids, are described.     

Thermal degradation of all-trans-β-carotene in the presence of phenylalanine

Solutions of all-trans-β-carotene in liquid paraffin were stirred under air at 210°C for 15 min in the presence and absence of various amino acids. After cooling, the absorbance values at 460 nm of model systems containing all-trans-β-carotene and phenylalanine, cysteine or tryptophan were 34–58 times higher than that obtained on heating in the absence of an amino acid. Based on absorbance values at 420 nm, 86% of the coloured material present on heating the all-trans-β-carotene-phenylalanine model system at 210°C for 15 min was retained by the liquid paraffin on methanol extraction. The liquid paraffin phase remaining after methanol extraction was analysed by reverse-phase HPLC and three major components were identified as all-trans-β-carotene and two degradation products of all-trans-β-carotene, ie 9-cis-β-carotene and a furanoid diepoxy derivative. None could be detected on heating all-trans-β-carotene alone, suggesting that its degradation was retarded on heating in the presence of phenylalanine.     

Supercritical fluid extraction of β-carotene from crude palm oil using CO2

The aim of this study was to ascertain the influence of pressure, temperature and time on the supercritical fluid extraction of β-carotene from the crude palm oil. The operating conditions were shown as follows: pressures of 75, 125 and 175 bar, temperatures of 80, 100 and 120 °C and extraction time of 1, 3 and 5 h. The extracts were analyzed using UV spectroscopy at a wavelength of 450 nm. Then the experimental data was compared with the data obtained using a statistical method. The results from the model showed a good agreement with the experimental data. The results (obtained from the statistical model) demonstrate that a pressure of 140 bar, temperature of 102 °C and extraction time of 3.14 h are required to obtain optimum yield of β-carotene (1.028 × 10⁻²%) from the extraction process, however the maximum yield of the β-carotene (1.741 × 10⁻²%) was experimentally obtained at a pressure of 75 bar, temperature of 120 °C and extraction time of 1 h.     

Pink discoloration in canned pears III.—Inhibition by chemical additives

Despite the identification of the pigment responsible for discoloration in canned pears as a tin–cyanidin complex, addition of stannous ions to susceptible pear purée prior to processing partly or completely inhibits the discoloration. This effect cannot be obtained with canned pear halves, but other reducing agents, such as sulphur dioxide, are effective inhibitors of the discoloration. By such treatment canned pears of acceptable quality can be produced from varieties which are normally avoided for processing because of their susceptibility to discoloration. A mechanism whereby reducing agents prevent the formation of pink pigments is described, and an explanation is given of the differences in the effect of stannous ions on pear halves and pear purées.