Characterization of the edible bird’s nest the “Caviar of the East”

A few species of swiflets (genus Aerodramus) build edible nests that are consumed by humans worldwide, as a delicacy known as the “Caviar of the East” or as a medicinal food. This study reports on the compositional properties of two types of nest, the white nest and the red “blood” nest. The order of composition (from lowest to highest) was found to be identical for both types of nests, i.e., lipid (0.14–1.28%), ash (2.1%), carbohydrate (25.62–27.26%) and protein (62–63%). It was also found that both nests share a common 77 KDa protein that has properties similar to those of the ovotransferrin protein in eggs. This protein may be partially responsible for the severe allergic reactions that sometimes occur among young children who consume edible bird’s nest products. It was found that SDS–PAGE electrophoretic fingerprinting might serve as a useful analytical technique for differentiating between white and red nests and for determining if the more expensive “blood” nest was adulterated with the less expensive white nest. Also evaluated were different analytical methodologies for detecting adulterants. Three of the most common adulterants found in retail bird’s nests are karaya gum, red seaweed, and tremella fungus, and they are routinely incorporated during commercial processing prior to final sale. Using crude protein determination, it was found that these adulterants (which typically accounted for 2–10% of the finished nest), reduce the overall crude protein content of the genuine white bird’s nest by as much as 1.1–6.2%. A modified xanthoproteic nitric acid test for proteins proved to be a rapid, and simple test to detect adulteration in both whole and finely ground nests, and would be suitable in the field where analytical facilities are not readily available.

After simple nitric acid treatment, visual examination and comparison of whole nests adulterated with karaya gum, red seaweed, and Tremella fungus against the authentic white nest revealed that levels of adulteration as low as 1.7%, 1.8%, and 3.5%, respectively, could be identified visually. In the case of finely ground nests, the visual detection level was higher for all three adulterants: 1.1% for karaya gum, 1.2% for red seaweed, and 2.0% for Tremella fungus. The use of a reflectance colourmeter rendered this test even more sensitive, allowing detection at even lower levels.     

Factors leading to the expression of “framboisé” in French ciders

During the last decade, observations on cider production sites allowed for some hypotheses to be made concerning relationships between “framboisé” (cider-sickness) development and physical and chemical cider parameters as well as some process operations. Although Zymomonas mobilis has long been known to cause cider-sickness in British ciders, it had never been detected in France until recently from a number of “framboisé” cases.The possibility to trigger “framboisé” in cider by inoculation of the bacterium allowed for a better understanding of the factors leading to “framboisé” development in ciders. The stage of the malo-lactic fermentation, amount of dissolved of oxygen, pH, combined effect of pH and sulfur dioxide and residual amount of utilizable yeast nitrogen (YAN) were studied.The main factor affecting cider sensitivity to “framboisé” is the amount of YAN. If the amount of YAN is sufficient, the development of “framboisé” will mainly be influenced by pH (sulfur dioxide playing a minor role).     

About Sr isotopes in coffee ‘Bourbon Pointu’ of the Réunion Island

Demonstration of the regional source of a high-quality product is nowadays essential to protect it from commercial transactions and cheatings. In this study, Sr isotopes are proposed as a tool to identify the regional source of a vegetable, on the basis of a combined geochemical investigation on a Coffea Arabica var. Laurina cultivation plot located on th Réunion Island. The Sr isotopic composition (⁸⁷Sr/⁸⁶Sr) of the produced coffee beans (called Pointed Bourbon) and of their growing environment, including soils, parent rocks, waters and fertilizers are determined. Flux of Sr in coffee beans is mainly dominated by soil solutions that can be influenced by Sr-rich fertilizers. This influence is however low enough to detect the cultivation soils’ Sr isotopic ratio in the vegetable product, even after roasting. It also allows discrimination of coffees produced on varied geological areas. Measurements performed on the same variety of coffee beans produced in New Caledonia strengthen the demonstration.     

Effect of phytate and storage conditions on the development of the ‘hard‐to‐cook’ phenomenon in common beans

Postharvest storage of beans (Phaseolus vulgaris L.) can alter the color, texture, flavor and time required for cooking. These alterations have been associated with the ‘hard‐to‐cook’ phenomenon (HTC) and a reduction in the quality of the grains. HTC has been linked to the genotype, environment and/or storage conditions of the grains, but very few studies have shown the interrelationship between these factors. Therefore, the objective of this study was to analyze the effect of two genotypes, Paraiso and Peruano, grown under the same phosphorus levels, on the development of HTC. These genotypes were evaluated for phytate, protein, tannin and phosphorus contents, hydration time and cooking time when stored for 45, 90 and 135 days, at 29 °C and 5 °C at a relative humidity of 75%. HTC was observed in Peruano after 135 days, which correlated with a reduction in the phytate content. Paraiso did not show HTC even though there was a reduction of tannins during the storage period. The lower storage temperature appeared to control HTC for both genotypes. Overall, the content of phytate can be an indicative factor for the cookability of fresh beans when the relationship between genotype and storage conditions has been determined. Copyright © 2007 Society of Chemical Industry     

Stereoselectivity of the β-lyase-catalyzed cleavage of <Emphasis Type="Italic">S</Emphasis>-cysteine conjugates of pulegone

Stereoisomers of 8-S-cysteinyl-p-menthan-3-one synthesized from (R)- and (S)- pulegone by Michael addition of cysteine were characterized by means of GC, GC-MS, LC-MS, and ¹H-NMR. Conjugates were treated with three sources of cysteine-S-conjugate #-lyase: (i) a crude enzyme extract prepared from Eubacterium limosum, (ii) tryptophanase from E. coli and (iii) yeast cells. The result was liberation of 8-mercapto-p-menthan-3-one, a powerful flavoring substance exhibiting a cassis-type odor note. The enzyme-catalyzed cleavage of the thio-ether bond proceeded with low enantioselectivity. Discrimination of diastereoisomers was more pronounced with a clear preference of the cis-configured substrates.     

Antioxidant Activities of the Supercritical and Conventional Satureja montana Extracts

ABSTRACT:  The antioxidant activities of the volatile and the nonvolatile fractions from  Satureja montana  obtained by supercritical fluid extraction (SFE) and by conventional techniques, hydrodistillation (HD) and soxhlet extraction (SE), were compared. A good agreement between DPPH and rancimat methods was obtained showing that the extracts were able to scavenge free radicals and to inhibit lipid oxidation. The volatile oil (obtained by SFE at 90 bar/40 °C) was the most effective extract, presenting the lowest EC₅₀ (0.06 g/L) and the highest protector factor (PF = 2.03). These results demonstrated the advantages of SFE over conventional techniques by avoiding thermodegradation and hydrolysis reactions. Furthermore, volatile oil is 15 times richer in thymoquinone than the essential oil (HD). This compound is of great importance due to its antioxidant, neuroprotective, and anti-cancer activities. The combination of carvacrol + thymol + thymoquinone in volatile oil may be responsible for the increase in the antioxidant activity when compared to HD, which demonstrates that, in this case, SFE improves value to the final product.     

Improvement of anthocyanin content in the cv. Öküzgözü wines by using pectolytic enzymes

The effect of the addition of two commercial pectolytic enzymes on the anthocyanin and chemical composition of Öküzgözü wines was studied. A rapid HPLC-diode array detection (DAD) method was developed for the analysis of anthocyanins in wines. Direct injection of filtered wine samples followed by selective detection at 520 nm allowed quantitation of these compounds in red wines. Thirteen anthocyanin compounds were detected in wines and, addition of the two enzyme preparations improved the extraction of anthocyanins. Moreover, the wines treated with enzymes had higher values in total phenolics, tannins, and colour intensity than the control wines.     

Effect of Centrifugation Conditions on the Cryotolerance of <Emphasis Type="Italic">Lactobacillus bulgaricus</Emphasis> CFL1

As the concentration step is usually considered to be responsible for cell damage, the objective of this work was to quantify the effect of centrifugation conditions (speed, duration, temperature, and pH) on the quality of Lactobacillus bulgaricus CFL1 starters. These effects were analyzed on the specific acidification activity of the cells, according to experimental designs. It is surprising to note that centrifugation conditions did not significantly affect the loss of specific acidification activity during the concentration step. In contrast, centrifugation speed and duration slightly altered cell resistance to freezing and frozen storage. No difference was observed when centrifugation was conducted at 4 or 15 °C. Finally, combining good centrifugation conditions to an acidification of the cells in their fermented broth strongly improved their cryotolerance. These results may have an impact for industrial starter production as they allowed modifying centrifugation conditions to better match the specificity and the viscosity of the medium.     

Study of the counts,species and characteristics of the yeast population during the manufacture of dry-cured “lacón”. Effect of salt level

The aim of this work was to study the yeast population during the manufacture of dry-cured “lacón” (a Spanish traditional meat product) and the effect of the salting time. For this study, six batches of “lacón” were manufactured with three different salting times (LS (3 days of salting), MS (4 days of salting) and HS (5 days of salting)). Yeast counts increased significantly (P < 0.001) during the whole process from 2.60 to 6.37 log cfu/g. An increased length of salting time did not affect yeast counts throughout the manufacture of dry-cured “lacón”, although the highest yeast counts were obtained from LS batches. A total of 226 isolates were obtained from dry-cured “lacón” during drying-ripening stage, of which 151 were yeasts and were identified at the species level using molecular techniques. The total of 151 identified yeasts belonged to 4 different genera: Debaryomyces, Candida, Cryptococcus and Rhodotorula. Debaryomyces hansenii was the most abundant species isolated throughout the whole process as much in the interior as in the exterior of the pieces of three salt levels of “lacón” studied, while Candida zeylanoides was only isolated from the interior of MS and HS batches and from the exterior of LS and HS groups, but at lesser proportion than D. hansenii.     

Compositional and degradative changes during the manufacture of dry‐cured ‘lacón’

The gross and mineral composition, the main physicochemical parameters, the protein extractability and the proteolytic (nitrogen fractions and free amino acids) and lipolytic (acidity index and free fatty acids) changes were studied throughout the manufacturing process of five batches of dry‐cured ‘lacón’, a traditional Spanish meat product made from the fore‐ham of the pig following a similar technological process to that of dry‐cured ham. The main compositional characteristics of this product are the high NaCl content and the low moisture content at the end of the curing process. The pH remained fairly stable (around 6) throughout the whole process and a fall in a_w was observed, reaching very low (0.767 ± 0.052) final average values. It was noted that 76% of the sarcoplasmic and 83% of the myofibrillar proteins became insoluble during the manufacturing process. The values of the different nitrogen fractions increased in a significant manner during manufacture, reaching low final values that indicate that ‘lacón’ undergoes a low level of proteolysis in comparison with other products manufactured by similar technologies. The high NaCl content and the intense dehydration suffered during the manufacturing process appear to be the principal causes of this reduced protein degradation. In accordance with the limited increase in the α‐amino acidic nitrogen during ripening, the total free amino acid content increased slightly but significantly from average values of 4371 mg kg^?1 dry matter in fresh pieces to average values of 13 020 mg kg^?1 dry matter in pieces at the end of the ripening process. The profile of free amino acids in the final product was similar to that observed by other authors in dry‐cured ham. The acidity of the fat increased by a factor of five. The final average values (49.9 g oleic acid kg^?1) were lower than those determined in dry‐cured ham, which indicates that ‘lacón’ undergoes less lipolysis during the ripening process than dry‐cured ham. C18 : 1, C18 : 2 and C16 were the most intensively released fatty acids during curing. The profile of free fatty acids in the end product was in agreement with that observed by other authors in dry‐cured ham. Copyright © 2003 Society of Chemical Industry     

"以人为本"理念下高教管理的发展探析

当前我国高校人才培养的主要途径是教学,而高教管理的最终目标就是为了实现教学目标而服务的管理模式。高教管理的本质是根据一定的方式方法,在高校内部营造良好的教学氛围与学术氛围,始终坚持一定的管理原则,从而有效组织教学活动的开展,在高校教学活动中做好全面指导与控制,促使教师与学生能够达到预期的教学目标与学习目标。因此,高教管理是影响高校教学与发展的关键性因素,具有不可替代的地位。本文从高教管理以人为本的内涵入手,简单阐述了以人为本的理念与内涵,并对当前高教管理存在的问题做了分析,最后提出在以人为本理念下高教管理发展的对策。     

Influence of hop harvest date of the ‘Mandarina Bavaria’ hop variety on the sensory evaluation of dry‐hopped top‐fermented beer

To impart a special hop aroma to beer, dry‐hopping is a technique that is becoming more and more popular with commercial breweries. Nevertheless, until now little was known about the factors that influence the reproducibility (and consistent product quality) of dry‐hopping with flavour varieties. One factor that could influence the sensory impressions and aroma profile compositions of dry‐hopped beers is the hop harvest date. Therefore, to determine the effects of different harvest dates of the flavour variety ‘Mandarina Bavaria’ on the aroma of top‐fermented beer, laboratory‐scale dry‐hopping trials were performed. Besides tasting sessions of brewed beers, relative quantities of selected hop‐derived, as well as beer‐originated aroma compounds, were investigated by headspace–solid‐phase microextraction–gas chromatography–mass spectrometry. Duo–trio tests between the beers hopped with pellets of different harvest dates showed no significant differences (α = 0.05) between them. In addition, these beers had similar profiles in a five‐point profile tasting scheme. On the other hand, relative concentrations of some hop‐derived aroma compounds – especially myrcene, which is known to be able to contribute to beer flavour – increased corresponding to a later harvest date, while beer originated volatiles were not different between the beers. Analytical results combined with the results of sensory evaluations led to the conclusion that the harvest date of Mandarina Bavaria was not a dominant factor in the dry‐hopping aroma of top‐fermented beers. High amounts of fermentation by‐products are likely responsible for masking effects resulting in no sensory distinctness between the samples with different hop aroma compound concentrations. Copyright © 2016 The Institute of Brewing & Distilling     

Effect of the inclusion of chestnut in the finishing diet on volatile compounds during the manufacture of dry-cured “Lacón” from Celta pig breed

The effect of the finishing diet on the volatile compounds throughout the manufacture of dry-cured “lacón” (a Spanish traditional meat product), from the Celta pig breed was studied. Thirty-six pigs were separated into three groups according to the type of feeding during the finish-fattening period of three months (concentrate, mixed diet and chestnut). From the pigs of each diet, four batches of dry-cured “lacón” were manufactured. From each batch, samples of fresh meat, meat after salting, after post-salting, and after 14, 28, 56 and 84 days of drying–ripening were taken. Volatiles were extracted by a purge-and-trap method and analyzed by gas chromatographic/mass spectrometry (GC/MS). Seventy-six volatile compounds were identified and quantified from dry-cured “lacón” samples in pigs finished with chestnut, eighty-two for concentrate fed pigs and eighty in pigs fed with the mixed diet. The number of identified volatile compounds increased during the manufacturing process; at 84 days of drying–ripening, in the dry-cured “lacón” samples from pigs finished with concentrate, mixed diet and chestnut, 54, 58 and 62 volatile compounds were detected, respectively. The most abundant group of flavour compounds at the end of the manufacturing process was hydrocarbons in the three feeding systems, followed by aldehydes, ketones and alcohols. Discriminant analysis selected six variables (dodecane, butadienol, pentenol, 2-pentenal, decen-3-ona and pyridine-2-methyl) and calculated two discriminating functions which allowed verification of chestnut in the finishing diet.