Utilisation of spontaneous emulsification to fabricate lutein‐loaded nanoemulsion‐based delivery systems: factors influencing particle size and colour

Factors influencing the formation and properties of lutein‐loaded nanoemulsions fabricated using spontaneous emulsification (SE) were investigated. Nanoemulsion formation depended on oil type: small droplets (diameter ≈ 200 nm) with a narrow monomodal particle size distribution (polydispersity index ≈ 0.23) could be formed using medium‐chain triglycerides (MCT), but not long‐chain triglycerides. Nanoemulsion formation also depended on surfactant type and concentration, with Tween 80 being the most effective surfactant. Optimisation of lutein‐loaded nanoemulsions formed by SE led to systems with a final composition of 10 wt% oil phase (0.12 wt% lutein + 9.88 wt% MCT), 10 wt% Tween 80, and 80 wt% aqueous phase. The nanoemulsions were stable to droplet aggregation when stored at ambient temperature for up to 1 month; however, some colour fading occurred due to lutein degradation. This study indicated the potential of nanoemulsion‐based delivery system fabricated using a low‐energy method for encapsulation and protection of lutein.     

Possible implications of milk pasteurization on the manufacture and sensory quality of ripened cheese

Cheese made from raw milk represents an important proportion of the traditional cheeses, particularly in South European countries. Besides destruction of pathogenic bacteria, the most significant changes in milk relevant to cheesemaking, which are induced by pasteurization are:

• a partial elimination of the milk microorganisms which may grow in cheese during ripening,

• a partial or total activation or inhibition of the plasmin/plasminogen complex, cathepsin D, lipoprotein lipase and alkaline phosphatase. Enzymes from psychrotrophic bacteria, acid phosphatase and xanthine oxidase, which may be active during ripening, withstand pasteurization.,

• a slight (7%) denaturation of serum proteins and little or no modification of the cheesemaking properties (coagulation, acidification by lactic acid bacteria).

From experimental work carried out on several cheese varieties, comparing pasteurized or microfiltered milk and raw milk cheeses, it was found that facultatively heterofermentative lactobacilli, Micrococcaceae, enterococci, and propionibacteria in Swiss-type cheese, are found at higher levels in raw milk cheese. The main biochemical modification of cheese during ripening concerns the nature and extent of proteolysis. Although there is no clear trend in the breakdown of _s1- and β-caseins, milk pasteurization leads to a significant decrease of the amount of small peptides and free amino acids and to different HPLC profiles. Experiments carried out with sensory analysis show that, in all cases, pasteurized or microfiltered milk cheeses have received lower flavour intensity scores than raw milk cheeses. From this review, it is concluded that the indigenous milk microflora, with its diversity of species and strains, appears to be mainly responsible of the specific sensory properties of raw milk cheeses.     

Reviewing the world's edible mushroom species: A new evidence-based classification system

Wild mushrooms are a vital source of income and nutrition for many poor communities and of value to recreational foragers. Literature relating to the edibility of mushroom species continues to expand, driven by an increasing demand for wild mushrooms, a wider interest in foraging, and the study of traditional foods. Although numerous case reports have been published on edible mushrooms, doubt and confusion persist regarding which species are safe and suitable to consume. Case reports often differ, and the evidence supporting the stated properties of mushrooms can be incomplete or ambiguous. The need for greater clarity on edible species is further underlined by increases in mushroom-related poisonings. We propose a system for categorizing mushroom species and assigning a final edibility status. Using this system, we reviewed 2,786 mushroom species from 99 countries, accessing 9,783 case reports, from over 1,100 sources. We identified 2,189 edible species, of which 2,006 can be consumed safely, and a further 183 species which required some form of pretreatment prior to safe consumption or were associated with allergic reactions by some. We identified 471 species of uncertain edibility because of missing or incomplete evidence of consumption, and 76 unconfirmed species because of unresolved, differing opinions on edibility and toxicity. This is the most comprehensive list of edible mushrooms available to date, demonstrating the huge number of mushrooms species consumed. Our review highlights the need for further information on uncertain and clash species, and the need to present evidence in a clear, unambiguous, and consistent manner.     

Wet deposition of polychlorinated biphenyls in urban and background areas of the Mid-Atlantic States

Spatial and temporal trends of polychlorinated biphenyl (PCB) concentrations in precipitation were measured at urban and background sites as part of the New Jersey Atmospheric Deposition Network (NJADN). The volume weighted mean concentration (VWM) of sigmaPCBs (sum of PCBs) based on precipitation measurements at three background sites was in the range of 0.30-0.50 ng/L. Concentrations in precipitation at two urban-industrial sites were on average 7-43 times higher than background concentrations. Wet deposition fluxes of sigmaPCBs at the two urbanized sites were 16 +/- 3.4 and 3.9 +/- 0.72 microg/m2-yr, while the background flux was approximately 0.30 microg/m2-yr. On average, 97% of the total atmospheric washout (WT) of PCBs resulted from particle scavenging. The fraction of atmospheric PCBs on particles was the best predictor of atmospheric washout in both urban (log WT = 0.71 (+/- 0.049) log psi + 4.9 (+/- 0.11); r2 = 0.81) and nonurban areas (log W(T) = 0.77 (+/- 0.083) log psi + 5.6 (+/- 0.16); r2 = 0.64). Wet deposition fluxes of sigmaPCBs are of the same order of magnitude as dry-particle deposition fluxes in all land-use regimes.     

Dietary manipulation of muscle long-chain omega-3 and omega-6 fatty acids and sensory properties of lamb meat

The effects of dietary manipulation of muscle long-chain omega-3 fatty acids (FA) on sensory properties of cooked meat in second cross ([Merino×Border Leicester]×Poll Dorset) wether lambs were evaluated. Lambs fed dietary supplements of fish meal (FM, Exp. 1) and fish oil (FO, Exp. 2) showed moderately (P<0.01) and markedly (P<0.001) increased muscle long-chain omega-3 FA content compared with those fed the basal diet of lucerne chaff and oat chaff. Protected canola seed (PCS, Exp. 1) significantly (P<0.001) increased omega-6 FA content of the longissimus muscle. In each of the 2 experiments (1 and 2), after being fed experimental diets for 6 weeks lambs were slaughtered at a commercial abattoir. At 24 h post-mortem (PM) the semitendinosus and biceps femoris muscles were removed from animals and stored at -20°C until evaluation of sensory properties using experienced panel members. The muscle samples were stored for 3 (Exp. 1) and 12 (Exp. 2) months then removed, thawed and cooked for sensory evaluation. The meat samples were cooked under standardized conditions in a convection microwave at 180°C (20-25 min) to an internal temperature of 75°C. Cooked samples were tested for flavour, aroma, juiciness and overall palatability. The significant increase in muscle long-chain omega-3 with FM (Exp. 1 and 2) and FO (Exp. 2) or omega-6 FA with PCS (Exp. 1) were not detrimental to sensory panel evaluations of flavour or aroma of cooked meat when compared with the basal diet. However, meat from FM (Exp. 1) had lower juiciness and FO (Exp. 2) had lower overall palatability. Protected sunflower meal protein with FO (Exp. 2) significantly lowered ratings for flavour, juiciness and overall palatability. Lamb meat with increased levels of long-chain omega-3 FA can be produced without altering the sensory quality (flavour or aroma) of the cooked meat.     

Methane cracking using Ni supported on porous and non-porous alumina catalysts

Porous and non-porous alumina catalysts were used as nickel supports to catalyze methane cracking. Different operating parameters were studied in a thermal gravimetric analyzer, including methane and hydrogen partial pressures, temperature and flow rate. During CH₄ cracking, carbon builds up on the catalyst surface and therefore the catalyst requires periodic regeneration. Cycling tests were performed, using air during the regeneration phase to burn off the carbon. The results showed that the non-porous catalyst performed better than the porous catalyst in terms of cracking during the first cycle. Full regeneration of the catalysts by oxidizing the deposited carbon was achieved at 550 °C, while oxidation was very slow at 500 °C. After full regeneration, the performance of the porous catalyst became considerably better than the non-porous. The porous catalyst kept its activity for 24 cracking/regeneration cycles, while the non-porous catalyst lost half of its activity by the second cracking cycle and almost all of its activity after six cycles. NiAl₂O₄ formation and Ni sintering caused the non-porous catalyst activity loss. TPO results showed that two carbon types were deposited on the catalysts, namely Cβ and Cγ, where Cβ is more active than Cγ.     

Glucosinolates in isaño (Tropaeolum tuberosum) tubers: qualitative and quantitative content and changes after maturity

Six varieties of isaño (Tropaeolum tuberosum), an Andean edible tuber, were analysed. The aim was to characterise qualitatively and quantitatively their content of glucosinolates and to determine concentration changes of these compounds upon delayed harvest. Additionally, exploratory assays were carried out on the effect of postharvest cold storage of the tubers as well as of a drying process imposed on blanched tuber slices. Only one glucosinolate (p‐methoxybenzyl glucosinolate) was found in the six domestic varieties analysed. Its concentration varied between 36.5 and 90.0 µmol g^?1 dry matter. This range is relatively high when compared with other edible glucosinolate‐containing vegetables. ‘Dark’ coloured tuber varieties showed higher levels than ‘light’ coloured tuber varieties at normal harvest time. Of the two varieties on which the effect of delayed harvest was studied, one showed increasing and then decreasing changes until 44 days after maturity, while the other did not show any significant change with time. Postharvest cold stored samples showed similar changes to tubers kept in soil, and glucosinolate levels in dried blanched tubers did not differ significantly from those in fresh samples. Taken together, the data indicate that the glucosinolate content of isaño is highly dependent on both the variety and the time of harvest. These parameters should be taken into account when considering isaño as a promising food source with medicinal properties for humans and animals, but also with possible adverse biological effects, all related to the presence of glucosinolates. Copyright © 2004 Society of Chemical Industry     

Antagonistic effect of fat on the antibotulinal activity of food preservatives and fatty acids

The effect of fat on the antibotulinal activity of 11 food preservatives, 12 free fatty acids, and nine lots of enzyme-modified cheese (EMC) was evaluated in a media system. Anhydrous milkfat or soybean oil was added to tubes of Trypticase–peptone–glucose–yeast extract medium (TPGY) supplemented with the additives (final pH adjusted to 5.9). Treatments were inoculated with 3-log₁₀ proteolytic Clostridium botulinum spores/ml (10-strain mixture of serotypes A and B) and incubated anaerobically at 30°C for up to 14 days. For the preservative and fatty acids studies, growth of C. botulinum was determined by measuring optical changes at OD_{640 nm}. Botulinal toxin production was determined in EMC-treatments using the mouse bioassay. Data revealed that the antibotulinal effects of nisin, and free fatty acids caprylic, capric, lauric, myristic, oleic, and linoleic acids were each significantly reduced in treatments supplemented with 20% fat (P<0.05). Similar trends were observed in TPGY supplemented with 20% fat and potassium sorbate, sorbic acid, monolaurin, polyphosphate emulsifier, or EDTA–lysozyme, but the differences were reduced. Fat was also antagonistic to the antibotulinal activity of five EMC-treatments. This study suggests that fat may reduce the efficacy of some antimicrobials added to or found naturally in foods.