1,721,014 research outputs found
Effect of dried liquorice root supplementation on chemical-nutritional quality of dairy products obtained from goats
No full textEnriching the goat’s diet with plant extracts, rich in bioactive compounds, allow to improve the chemical-nutritional properties of dairy products. Liquorice has anti-inflammatory, antimicrobial, antioxidative effects associated with the presence of compounds, as triterpene saponins, flavonoids and coumarins The aim of the present work was to evaluate the effect of dietary integration with 8% of dried liquorice root on chemical-nutri- tional quality of goat milk and cheeses. The study was conducted for 60 days on Saanen goats divided into two groups: a control group (CG) and an experimental group (LG+) whose diet was supplemented with liquorice. Milk samples were collected to determinate chemical-nutritional composition and fatty acids profile (FA) at 30 and 60 days from the beginning of the study. At the end of the experiment, cheeses produced with CG and LG + bulk milk were analysed for chemical–physical parameters at 3 (T3) and 60 (T60) days of ripening.
A different FA profile and a significant increase in proteins (p<.01) and casein (p<.01) percentage but no variation in lipids, lactose, urea and in FA were observed in LG+milk samples respect to CG milk. Regarding cheeses, no variation in lipid and protein but a lower water content (p<.05) were found in LG + T3 and T60 cheeses, this reflected in a different texture. Indeed, the LG+cheeses were harder, more elastic and more gummy than the CG cheeses and these differences were observed both in fresh and aged cheeses. Moreover, the LG + cheeses showed a yellowish colour probably correlated to the presence in LG + milk of specific compounds of liquorice roots, such as tannins, carotenoids and ascorbic acid which have antioxidant activity and are also respon- sible for the yellow colour. A greater presence of antioxidant compounds deriving from liquorice roots can be also correlated with greater oxidative stability found in both LG + T3 (p<.05) and T30 (p<.05) cheeses. Different families of volatile compounds were detected in T30 cheeses obtained from the two groups. A significant reduction of octanoic acid (p<.05) and a significant increase in nonanal (p<.01) were found in LG+T3 cheeses, instead in LG + T60 cheeses, significant increases of 3-methyl, 1-butanol (p<.01) and acetoin (p<.05) have been found.
In conclusion, it is possible to assert that the integration with liquorice has modified chemical and technological properties of goat cheeses, improving the oxidative stability and inducing changes in texture and colour
Dietary selenium supplementation of Friesian cows modifies the aromatic profile of dairy products
No full texthis study aimed to investigate the effect of dietary selenium (Se) supplementation of Friesian cows on the aromatic properties of dairy products. Thirty-two Friesian cows, balanced for parity, milk production and days in milk, were randomly assigned to 2 groups. The trial lasted 63 days in which the control group (CG) was fed with a conventional feeding strategy, while the experi- mental group (SeG) received daily selenomethionine (SeMet) supplementation. During the experimental period, the milk yield was monitored and samples of milk and related Caciocavallo cheese were collected and analysed in order to obtain information on chemical-nutritional composition. To evaluate the effect of ripening on the aromatic profile, the analysis was performed on cheese samples collected after 7 (T7) and 120 (T120) days after the cheese-making. The volatile compounds composition resulted positively affected by dietary Se intake, with a significant increase in concentration of carboxylic acids, esters and lactones (p<.05), reflecting the predominance of the lipolytic processes respect to the proteolytic events. The general increase of carboxylic acids in ripened cheese could be explained by the extent of starter cell autolysis, with the consequent release of peptidases and espe- cially lipases that accelerate the lipolytic events. Among the most represented carboxylic acids must be indicated butanoic and
ANIMAL PRODUCTS
hexanoic acids; such compounds are considered to be mainly involved in the determination of cheese flavour, giving origin to cheesy, rancid and sweaty odours. The increased production of such compounds could be probably explained by an increase of lipolysis of the triglycerides by microbial and endogenous milk enzymes, resulting in an augmented release of free fatty acids (FFAs). With regard to the esters, such compounds are charac- terised by a low odour threshold and are generally associated with the sweet, fruity, and floral notes of surface-ripened cheese fla- vour. Lactones, instead, are generally produced by a one-step transesterification reaction of hydroxylated FFAs which represent the main precursors. Such findings could contribute to the pro- duction of cheeses with interesting organoleptic properties, although further sensorial evaluations should be performed to deeply investigate these changes and confirm the consumer acceptability
Feeding influence on the oxidative stability of poultry meat treated with ozone
Full text linkOzone is considered a strong antimicrobial agent with numerous potential applications in alimentary industry. However, its high oxidizing potential can induce alterations in foods by acting in particular on the unsaturated fatty acids. The aim of this study was to investigate the effect of ozonation on the oxidative stability of chicken breast meat obtained from animals subjected to different feeding strategies
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Volatile Flavor Compounds in Cheese as Affected by Ruminant Diet
Full text linkExtensive research has been conducted concerning the determination and characterization of volatile compounds contributing to aroma and flavor in cheese. Considerable knowledge has been accumulated on the understanding of the mechanisms through which these compounds are formed during ripening, as well as on the optimization of the methodological approaches which lead to their detection. More recently, particular attention has been given to the aromatic properties of milk and cheeses obtained from lactating dairy ruminants fed experimental diets, characterized, for instance, by the addition of trace elements, natural supplements, or agricultural by-products rich in bioactive compounds. The purpose of this review is to summarize the major families of volatile compounds most commonly found in these types of dairy products at various ripening stages, describing in greater detail the role of animal diet in influencing the synthesis mechanisms most commonly responsible for cheese flavor determination. A large number of volatile compounds, including carboxylic acids, lactones, ketones, alcohols, and aldehydes, can be detected in cheese. The relative percentage of each compound depends on the biochemical processes that occur during ripening, and these are mainly mediated by endogenous enzymes and factors of bacterial origin whose function can be strongly influenced by the bioactive compounds taken by animals with the diet and released in milk through the mammary gland. Further evaluations on the interactions between volatile compounds and cheese matrix would be necessary in order to improve the knowledge on the synthesis mechanisms of such compounds; in addition to this, more should be done with respect to the determination of synergistic effects of flavor compounds, correlating such compounds to the aroma of dairy products
Effect of diet supplement in dairy cow with grape pomace on quality of milk and cheese
No full textThe aim of the study was to evaluate the effect of dairy cow diet supplement with grape pomace (GP) on quality of
milk and cheese derived. The GP, a biomass deriving from winery and distillery industries, is a source of polyphenols
and unsaturated fatty acids. Twelve lactating Holstein Friesan cows were randomly divided in two homogenous
groups for parity, milk yield and days in milk. Cows were fed during 60 days with conventional ration in the control
group (CG) and with GP (10% on daily dry matter intake) as supplement of conventional ration in the experimental
one (EG). Samples of both diet were collected for chemical analyses. Milk production was monitored during the
trial and individual milk samples were collected at the end of the experiment for both groups. Milk samples were
analyzed to evaluate quality parameters (protein, casein, lactose, lipids, fatty acids profile, urea and somatic cells).
Milk produced the last day of the experimental period was collected for both groups and used to produce cheese.
Cheese was sampled at 1 (T1) and 30 (T30) days over ripening and fatty acids profile and lipid oxidation (TBARs
test) were assessed. Statistical analysis was carried out using GLM procedure of SAS. Chemical analyses performed
on diets highlighted a higher content of linoleic acid in EG diet compared with the CG one (46.73 vs 40.11%,
respectively). Milk yield did not differ between two groups during the experimental time (16.58 vs 15.29 kg/d, CG
and EG group respectively). Vaccenic (0.95 vs 1.45%), rumenic (0.55 vs 0.91%) and linoleic (2.05 vs 2.60%) acids
were significantly higher in EG milk compared to CG one. Fatty acids composition of cheese, in particular vaccenic,
rumenic and linoleic acids, were higher in EG group. Malondialdehyde did not differ at T1 between groups while
it resulted almost three times lower in EG cheese after 30 days of ripening (0.117 vs 0.043 μg MDA/g). Results
indicate that GP diet supplement in dairy cows may enhance milk and cheese fatty acids composition. The lowest
lipid oxidation observed in treated cheese may be related to antioxidant properties of the higher concentration of
polyphenols in grape pomac
Effect of cow feeding supplementation with olive pomace on the development of aromatic compounds in milk and dairy products
No full textUtilization of agro-industrial by-product in animal feeding represents
an interesting and sustainable alternative to its
disposal.
The aim of this study was to evaluate the effect of olive pomace
(OP) as supplement feed in dairy cow on aromatic compounds
in raw milk, spontaneous fermented milk and cheese.
Twenty lactating cows were randomly divided in two homogenous
groups and fed for 60 days with OP supplement (2 Kg
DM/cow/die) in the experimental group (EG) and without in
the control one (CG). Diets were isoenergetic and isoproteic.
Samples of bulk milk were collected at the end of the trial for
both groups. Some of these were spontaneously fermented at
25 C for 72h and thereafter analyzed. The rest of bulk milk
was used to produce cheese that was sampled at 1, 7 and 30
days of ripening. A SPME-GC-MS analysis was performed to
detect volatile compounds. Data were analyzed with GLM procedure
and significance were set at p<.05.
In raw milk, besides free fatty acids, several secondary lipolysis
catabolites (ethyl and methyl esters, lactones, aldehydes,
methyl ketones) were detected and most of them (65%) were
higher in EG (p<.01).
Higher lypolitic activity (48% of compounds) in fermented
milk was recorded in EG confirming that already observed in
raw milk (p<.05). Esters deriving from methionine catabolism
were higher in EG fermented milk (p<.05). On the other
hand, data generally showed an increase of first catabolites of
branched amino acids in CG milk, while 45% of their related
esters were most detected in the EG (p<.05).
Analysis of cheese highlighted differences (p<.05) between
groups in some flavoring catabolites achieved at different
times during ripening. Lypolitic catabolites were generally
higher in the EG, especially at T7, with the exception for
d-nonalactone that was most observed in CG at every time
(p<.05). First leucine catabolites (a-ketoisocaproic acid,
a-hydroxyisocaproic derivative) were greater in EG cheese at
every time (p<.05), while 3-methylbutanol were higher in EG
at T7 (p<.001) and T30 (p<.05). Their related esters, isoamyl
isopentanoate and isoamyl butyrate, increased in EG at
T7 and T30 (p<.01) and at T30 (p<.05), respectively.
In conclusion, dietary supplement with olive pomace may
affect lypolisis and proteolysis processes responsible of dairy
products aroma. This pattern was already observed in raw
milk and confirmed also in fermented milk and cheese, especially
for compounds produced by esterase activity
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