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1.
J Food Sci ; 85(1): 36-49, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31898814

RESUMO

Miracle fruit's potential benefit is encouraging as a powerful antioxidant and sweetness enhancer due to its novel ability to modify sour taste to sweet. However, further studies are needed to evaluate the practicality of different miracle fruit products. Thus, this study aimed to characterize the taste modification effects of different miracle fruit products on different sour foods. For this, 10 trained subjects (80% female, 50% white, Mean ± SE = 27.3 ± 3.9 years old) performed a Quantitative Descriptive Analysis using a Latin Square design with three replications. One session was composed of pre- and posttest for miracle fruit administration. Five food samples (green apple, goat cheese, lemonade, plain fat-free yogurt, and cucumber pickle) and four miracle fruit products (three different brands of miracle fruit pill-Y, G, M and one powder product-P) were used and data were analyzed using analysis of variance and principal component analysis. The typical effects of miracle fruit, sweetness increase and sourness suppression were observed for all food samples albeit to different degrees. Y and M pills were most impactful while powder product was least, and goat cheese and yogurt had the most pronounced impact at increasing sweetness. Prior Miracle Fruit administration significantly decreased bitterness and increased creaminess in yogurt. However, it increased off-flavor in lemonade and pickle. Results suggest that miracle fruit usage for increasing sweetness is effective but the degree of taste-modifying effect differs according to the types of miracle fruit product and food samples applied. PRACTICAL APPLICATION: This research confirms miracle fruit's unique taste-modifying abilities and demonstrates a high potential as a sweetness enhancer to benefit human health. The results can be used to optimize miracle fruit's application and can be applied by food industry and health care provider to develop clinical remedies or disease prevention strategies.


Assuntos
Synsepalum/metabolismo , Adulto , Queijo/análise , Cor , Feminino , Aromatizantes/metabolismo , Frutas/metabolismo , Humanos , Masculino , Malus/metabolismo , Análise de Componente Principal , Paladar , Iogurte/análise , Adulto Jovem
2.
Food Microbiol ; 87: 103383, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31948624

RESUMO

Thermophilic and mesophilic lactic acid bacteria (LAB), such as Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus helveticus, and Lactococcus lactis, play a crucial role in the technological and sensory quality of Mozzarella cheese. In this study, the safety (genes encoding virulence factors and antibiotic resistance) and acidifying activity of autochthonous S. thermophilus cultures were evaluated in order to choose the most suitable strain for industrial application. The safe and good acidifying culture was tested in two buffalo Mozzarella cheese batches: Mozzarella cheeses produced with autochthonous culture (SJRP107) and commercial culture (STM5). The cultivable LAB was evaluated by culture-dependent method (plate counting) and the quantification of S. thermophilus cultures (commercial and autochthonous) were evaluated by culture-independent method RealT-qPCR (real-time quantitative polymerase chain reaction). The texture, physicochemical and proteolytic properties of the Mozzarella cheeses were similar for both batches. The nonstarter LAB count was higher during manufacture than in the storage, and the RealT-qPCR indicated the presence of S. thermophilus culture until the end of storage. S. thermophilus SJRP107 presented high potential for safety application in the production of Mozzarella cheese. Furthermore, considering the culture characteristics and their relationship with product quality, further studies could be helpful to determine their effect on the sensory characteristics of the cheese.


Assuntos
Queijo/microbiologia , Leite/microbiologia , Streptococcus thermophilus/crescimento & desenvolvimento , Streptococcus thermophilus/metabolismo , Animais , Búfalos , Queijo/análise , Qualidade de Produtos para o Consumidor , Fermentação , Microbiologia de Alimentos , Humanos , Streptococcus thermophilus/genética , Streptococcus thermophilus/isolamento & purificação , Paladar
3.
J Sci Food Agric ; 100(3): 995-1003, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31646635

RESUMO

BACKGROUND: New techniques are required to guarantee the authenticity of food, especially for PDO (Protected Designation of Origin) trademarks. The genuineness of a product is directly related to the raw material and to the production process used. In this article, the traceability of the Mozzarella di Bufala Campana PDO was investigated, using carbon, nitrogen and oxygen stable isotopes ratios, measured on buffalo feeding, milk and mozzarella, from Caserta and Salerno farms. Furthermore, 37 mozzarella brands were analyzed (carbon, nitrogen and oxygen isotopes) from the different production areas, to characterize their origin. RESULTS: The results of this work showed no changes in carbon and nitrogen isotopic ratios of milk and mozzarella, indicating no fractionation in the production process. The δ13 C of milk was influenced by feeding signal; while, milk δ15 N was regulated by fractionation occurring during ruminant metabolism. Mozzarella oxygen isotopic signal depleted with respect to the milk one. Regarding brand samples, it was found that the geographical differentiation is based more on carbon isotopes than on the nitrogen and oxygen ones. CONCLUSION: This work gives an important contribution to the knowledge regarding the traceability of such a particular cheese as mozzarella. © 2019 Society of Chemical Industry.


Assuntos
Isótopos de Carbono/análise , Queijo/análise , Contaminação de Alimentos/análise , Isótopos de Nitrogênio/análise , Isótopos de Oxigênio/análise , Ração Animal/análise , Animais , Búfalos/metabolismo , Leite/química , Leite/metabolismo
4.
J Dairy Sci ; 103(1): 63-71, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31629509

RESUMO

The high nutritional value of sheep milk can be advantageous in the manufacture of cheese, and fat plays an important role in sheep cheese properties. The aim of this study was to investigate the effect of feeding common hay or silage diets used in commercial farms on the nutritional value of sheep cheese fat. We also monitored the effect of cheese ripening period on the fatty acid profile. Cheeses were produced from milk of sheep fed hay and silage diets from 8 farms, on 4 separate occasions (February, May, August, and November) over a 1-yr period. Eighty-four individual fatty acids were determined and identified by gas chromatography. Ripening time (100 and 180 d) significantly reduced moisture, acidity, and water activity of cheeses but did not affect the fatty acid content. However, hay feeding, compared with silage feeding, led to cheeses with 1.5- and 1.3-fold higher contents of vaccenic acid and conjugated linoleic acid, without detrimental changes in saturated and n-3 (omega-3) fatty acid composition. Hay forages could be a low-cost alternative for producing cheese with a fatty acid profile suitable for human health, which is an aspect of great interest to the food industry.


Assuntos
Ração Animal/análise , Queijo/análise , Dieta/veterinária , Leite/química , Ovinos/fisiologia , Animais , Ácidos Graxos/química , Feminino
5.
J Dairy Sci ; 103(1): 52-62, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31704006

RESUMO

The aim of the present study was to evaluate the effect of dietary integration with dried licorice root on the chemical-nutritional qualities of goat milk and cheeses. The study was conducted for 60 d, during which 30 Saanen goats were divided into 2 groups: a control group (CG) that received a standard diet and an experimental group (LG+) whose diet was supplemented with licorice. At the end of the study, milk samples were collected to determine chemical-nutritional compositions and fatty acid (FA) profiles. Cheeses produced with CG and LG+ bulk milk were analyzed for chemical-physical parameters after 3 (T3) and 30 (T30) d of ripening. A different FA profile and a significant increase in protein and casein were observed in LG+ milk samples compared with CG milk. Regarding cheeses, an increase of proteins and fat was found in LG+ cheeses, which also were harder, more elastic, and more gummy than the CG samples after both 3 and 30 d of ripening. A different protein profile was detected in the 2 groups without significant variations in casein fractions (αS2-casein and ß-casein) during ripening. Moreover, greater oxidative stability was found in LG+ cheeses at both T3 and T30. Different families of volatile compounds were detected in T30 cheeses obtained from both groups. A significant reduction of octanoic acid and an increase in nonanal and ketones were found in LG+ T3 cheeses, whereas the LG+ T30 cheeses were characterized by a significant decrease of hexanoic acid an increase of 3-methyl-1-butanol and acetoin. We concluded that it is possible to assert that dietary integration with dried licorice root modified chemical and technological properties of goat cheeses, reducing lipid oxidation during ripening and inducing changes in texture that could improve consumer acceptability, although further studies are needed from this point of view.


Assuntos
Queijo/análise , Dieta/veterinária , Glycyrrhiza , Cabras/fisiologia , Leite/química , Ração Animal , Fenômenos Fisiológicos da Nutrição Animal , Animais , Caseínas/análise , Suplementos Nutricionais , Ácidos Graxos/análise , Análise de Alimentos , Valor Nutritivo
6.
J Dairy Sci ; 103(1): 201-209, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31677839

RESUMO

Concentrating milk by reverse osmosis (RO) has the potential to increase cheese yield but is known to impair cheese-making properties. The main compositional differences between ultrafiltration (UF) and RO concentrates are the high lactose and mineral contents of the latter. The objective of this work was to determine the distinct effects of high lactose and high minerals on the cheese-making properties of RO concentrate, by supplementing UF concentrate with lactose. The soluble colloidal equilibria of concentrates were studied as well as several other properties: rennet gelation behavior, cheese mass balance, composition, and microstructure. Rennet coagulation time was longer and gel firming rate was lower for RO concentrate than for UF concentrate. Lactose was mainly responsible for these differences. Lactose in RO concentrate was also responsible for the 7% increase of moisture-adjusted cheese yield, relative to UF concentrate. Compared with cheese made from UF concentrate, cheese made from RO concentrate showed higher moisture content, which could not be attributed to lactose but to the high mineral concentration. This study showed the potential of using RO instead of UF concentrate to maximize cheese yield. The approach is, however, limited to applications where post-acidification can be controlled, and will require appropriate strategies to reduce the negative effects of high mineral content in RO concentrate.


Assuntos
Queijo/análise , Manipulação de Alimentos/instrumentação , Lactose/análise , Minerais/análise , Osmose , Ultrafiltração/instrumentação
7.
J Dairy Sci ; 103(1): 228-241, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31704005

RESUMO

In humid temperate regions, forage turnip (Brassica rapa ssp. rapa) and forage rape (Brassica napus ssp. biennis) are common fodder crops used for dairy cattle during the summer season. However, there is little scientific information regarding the use of brassicas and their effect on the fatty acid (FA) profile in blood, milk, and milk products. The aim of this study was to evaluate the effect of forage brassica supplementation in dairy cows on the FA profile of blood plasma, milk, and cheese, and on the sensory characteristics of Chanco and Ricotta cheeses. Twelve multiparous dairy cows (Holstein Friesian) were housed and submitted to a 3 × 3 replicated (n = 3) Latin square design with 3 treatments (control, turnip, or rape) in 3 periods of 21 d each (14 d of diet adaptation and 7 d of measurements). The control diet consisted of 16.20 kg of grass silage (Lolium perenne), 2.25 kg of soybean bran, and 2.25 kg of commercial concentrate, all on a dry matter (DM) basis. In the treatments with forage brassicas, 24.15% of the total DM was replaced by turnip or rape; thus, they consisted of 12.25 kg of silage, 2.25 kg of soybean bran, 1.2 kg of concentrate, and 5 kg of turnip or rape (DM basis). A principal components analysis was performed on the results of the cheese sensory evaluation. Supplementation with turnip or rape modified the profile of FA in blood plasma and milk, increasing the saturated fraction, mainly short- and medium-chain FA, and decreasing the mono- and polyunsaturated FA. In the sensory evaluation, diet did not affect any of the 18 attributes evaluated. However, in the principal components analysis, cheeses made with milk from animals fed turnip and rape were differentiated by increased odor, flavor, spiciness, bitterness, and acidity. Overall, brassicas can be used as an alternative forage source with no negative effects on sensory characteristics of cheeses.


Assuntos
Brassica napus , Brassica rapa , Bovinos/fisiologia , Queijo/análise , Ácidos Graxos/análise , Silagem/análise , Animais , Chile , Dieta/veterinária , Suplementos Nutricionais/análise , Feminino , Lolium , Soja
8.
J Dairy Sci ; 103(1): 242-253, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31733845

RESUMO

Lactococcus lactis is the lactic acid bacteria most frequently used for the production of cheese starter cultures, mainly because of their efficient production of aroma compounds. However, commercial cultures do not always produce the typical aroma notes of artisanal raw-milk cheeses. Thus, the objective of this study was to characterize the volatile compounds generated by wild L. lactis strains in Mexican Fresco cheese made with pasteurized milk. Four strains of wild L. lactis were evaluated for their aroma production in Mexican Fresco cheese using sensory and instrumental analysis. The aroma profiles were evaluated by descriptive sensory analysis. Volatiles were determined by solid-phase microextraction and gas chromatography-mass spectrometry. Principal component analysis was applied to interpret analytical and sensory data. Mexican Fresco cheese aroma was described as milkfat, yogurt, yeasty, barny, dirty socks, and Fresco cheese. Cheese with L. lactis strains R7 or B7 were most similar to commercial raw milk Fresco cheese in all aroma descriptors. Volatiles identified in all cheeses were esters, acids, alcohols, ketones, and aldehydes, but the main differences were found for total volatile relative abundance. Also, volatile concentrations (µg/g) in commercial raw milk Fresco cheese and cheeses made with L. lactis R7 or B7 were 4 methyl esters [C4 (4.15 vs. 5.47-13.74), C6 (0.12 vs. 1.53-15.34), C8 (1.06 vs. 0.32-6.65), and C10 (0.62 vs. 0.41-3.74)], 7 acids [C4 (1.92 vs. 0.30-9.29), C6-C10 (0.05-4.48 vs. 0.11-30.45), and C12 (0.13 vs. 0.28-0.30)], 2 alcohols [(3-methyl-1-butanol (3.48 vs. 3.4-13.13) and phenylethyl alcohol (0.10 vs. 0.63-2.04)], and 1 ketone (acetoin; 1.22 vs. 0.28-0.99). The first 3 principal components explained 78.2% of the total variation and clearly distinguished 3 main groups. Cheese made with L. lactis R7 was classified in the same group as key compounds associated with Fresco cheese aroma and show potential as a starter in Mexican Fresco cheese manufacture.


Assuntos
Queijo/análise , Lactococcus lactis/química , Odorantes/análise , Cromatografia Gasosa-Espectrometria de Massas , México , Análise Multivariada , Microextração em Fase Sólida , Especificidade da Espécie
9.
Food Chem ; 303: 125390, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31450177

RESUMO

Cheddar cheese predicted to develop into different quality classes has been evaluated by time domain Nuclear Magnetic Resonance, Thermogravimetric analysis and quantitative sensory analysis. The water and fat proton signals in the transverse relaxation decay curves have been deconvoluted. Proton transverse relaxation values for both the water and fat fractions decrease and the relative %age of the proton peak area, predominantly from the fat increases over a 450-day ripening period. The thermodynamic free water percentage increases during maturation. Water and fat attributes can distinguish between Cheddar cheese batches after 56 days. Cheese batches which have lower transverse relaxation values for the water and fat proton fractions and a higher relative %age of the proton peak area predominantly from fat at 56 days, mature after 270 days to be more yellow, rubbery and smooth, have a less sour and lingering aftertaste and are also harder to form into a cheese ball.


Assuntos
Queijo/análise , Gorduras/análise , Manipulação de Alimentos , Água/análise , Espectroscopia de Ressonância Magnética , Paladar , Tempo
10.
Food Chem ; 305: 125480, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31522125

RESUMO

Milk samples from 1264 cows in 85 farms were authenticated for different farming-systems using a 10-fold cross-validated linear-discriminant-analysis using Fourier-transform infrared spectra (FTIRS) and gas-chromatographic fatty-acid (FA) profiles. FTIRS gave correct classification greater than FAs (97.4% vs. 81.1%) during calibration, but slightly worse in validation (73.5% vs 77.3%) and their combination improved the results. All milk samples were processed into ripened model-cheeses, and analyzed by near-infrared-spectrometry (NIRS), by proton-transfer-reaction time-of-flight mass-spectrometry for their volatile organic compound (VOCs) fingerprint and by panel sensory profiling (SENS). Farming-system authentication on cheese samples was less efficient than on milk, but still possible. The instrumental methods yielded similar validation results, better than SENS, and their combination improved the correct classification rate. The efficiency of the different technics was affected by specific farming systems. In conclusion, dairy products could be discriminated for farming-systems with acceptable accuracy, but the methods tested differ in sampling procedure, rapidity and costs.


Assuntos
Queijo/análise , Ácidos Graxos/química , Aromatizantes/análise , Leite/química , Animais , Bovinos , Cromatografia Gasosa , Análise Discriminante , Ácidos Graxos/análise , Feminino , Análise de Alimentos , Espectrometria de Massas , Espectroscopia de Infravermelho com Transformada de Fourier , Compostos Orgânicos Voláteis/análise
11.
J Sci Food Agric ; 100(2): 811-816, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31617212

RESUMO

BACKGROUND: Natamycin is often added to pastries, cheeses, and beverages. The residual amount of natamycin should be less than 10 mg kg-1 . The current method for its determination in various foodstuffs is high-performance liquid chromatography (HPLC). Capillary electrophoresis (CE) is a simple, fast, and environmentally friendly method with low reagent consumption and comparable separation performance. However, no reports were found on the determination of natamycin in foods by CE. A CE method to determine natamycin is therefore sought. RESULTS: Natamycin in foods was determined by the capillary zone electrophoresis (CZE) method with ultraviolet-visible (UV) detection. Separation conditions were optimized as 20 mM Na2 HPO4 , pH 9.2, with 25 kV applied voltage, and UV detection at 306 nm. Under optimal conditions, electrophoretic analysis was completed in less than 4 min, with a limit of detection (LOD) of 0.065 µg mL-1 and limit of quantitation (LOQ) of 0.22 µg mL-1 . A good linear relationship (r2 = 0.999) was obtained at the range of 0.1-25 µg mL-1 . A comparison with the HPLC-UV method was also carried out according to the National Standards of the People's Republic of China. CONCLUSION: The results obtained by the CZE and HPLC methods are comparable but the proposed CZE method can help us obtain a shorter detection time at low cost. © 2019 Society of Chemical Industry.


Assuntos
Bebidas/análise , Queijo/análise , Cromatografia Líquida de Alta Pressão/métodos , Eletroforese Capilar/métodos , Conservantes de Alimentos/análise , Natamicina/análise , China , Limite de Detecção
12.
Crit Rev Food Sci Nutr ; 60(1): 33-47, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-30285475

RESUMO

Cheese is a fermented dairy product, harboring diverse microbial communities (microbiota) that change over time and vary depending on the type of cheese and their respective starter and adjunct cultures. These microorganisms play a crucial role in determining the flavor, quality and safety of the final product. Exploring the composition of cheese microbiota and the underlying molecular mechanisms involved in cheese ripening has been the subject of many studies. Recent advances in next generation sequencing (NGS) methods and the development of sophisticated bioinformatics tools have provided deeper insights into the composition and potential functionality of cheese microbiota far beyond the information provided by culture-dependent methods. These advances, which include rRNA gene amplicon sequencing and metagenomics, have been complemented and expanded in recent years by the application of metatranscriptomics, metaproteomics and metabolomics. This paper reviews studies in which application of these meta-omics technologies has led to a better understanding of the microbial composition and functionality of cheese and highlights opportunities by which the integration of outputs from diverse multi-omics analytical platforms (cheesomics) could be used in the future to advance our knowledge of the cheese ripening process and identify biomarkers for predicting cheese flavor, quality, texture and safety, and bioactive metabolites with potential to influence human health.


Assuntos
Queijo/análise , Microbiologia de Alimentos , Microbiota , Queijo/microbiologia , Biologia Computacional , Metagenômica , Paladar
13.
Food Microbiol ; 86: 103348, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31703879

RESUMO

The effects of the incorporation of the essential oils from Origanum vulgare L. (OVEO; 0.07 µL/g) and Rosmarinus officinalis L. (ROEO; 2.65 µL/g) in combination in Minas Frescal cheese on the counts of the probiotic Lactobacillus acidophilus LA-5 and Escherichia coli O157:H7 were evaluated during refrigerated storage (7 ±â€¯0.5 °C). The terpenes of OVEO and ROEO, survival of the probiotic strain during in vitro digestion, as well as the physicochemical and sensory aspects were also monitored in Minas Frescal cheese. All terpenes decreased in cheese when the storage time increased. The incorporation of OVEO and ROEO delayed the increase in L. acidophilus LA-5 counts in cheese, but did not affect its ability to survive in cheese under simulated gastrointestinal conditions. The decreases in counts of E. coli O157:H7 observed in the first 15 days of refrigerated storage were strongly correlated (r ≥ 0.82) with the terpenes detected in cheese. Scores attributed for aroma, flavor, overall impression and purchase intention of cheese with OVEO and ROEO increased with the increase of the storage time. The incorporation of OVEO and ROEO in combination could be a strategy to control E. coli O157:H7 in probiotic Minas cheese during storage; however, the amounts of these substances should be cautiously selected considering possible negative sensory impacts in this product.


Assuntos
Queijo/microbiologia , Escherichia coli O157/crescimento & desenvolvimento , Aditivos Alimentares/análise , Lactobacillus acidophilus/crescimento & desenvolvimento , Óleos Voláteis/análise , Origanum/química , Óleos Vegetais/análise , Rosmarinus/química , Queijo/análise , Escherichia coli O157/efeitos dos fármacos , Aditivos Alimentares/farmacologia , Humanos , Lactobacillus acidophilus/efeitos dos fármacos , Viabilidade Microbiana/efeitos dos fármacos , Óleos Voláteis/farmacologia , Óleos Vegetais/farmacologia , Paladar
14.
J Agric Food Chem ; 67(49): 13684-13693, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31742396

RESUMO

A novel BL312 milk-clotting enzyme (MCE) exhibited high-level expression and remarkable milk-clotting activity (MCA) (865 ± 20 SU/mL) that was 3.3-fold higher than the control by optimizing induction conditions in recombinant Escherichia. coli harboring pET24a-proMCE. Through substrate-binding region analyses and modification, MCE-G165A was identified from nine mutants and showed a proteolytic activity of 49.4 ± 2.4 U/mL and an MCA/PA ratio of 18.2, which were respectively 1.9-fold lower and 2.0-fold higher than those of the control. The purified MCE-G165A (28 kDa) exhibited weak αs-casein, ß-casein, and strong κ-casein (κ-CN) hydrolysis levels as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and reversed-phase high-performance liquid chromatography. The milk-clotting mechanism for MCE-G165A was the primary hydrolysis of Met106-Ala107 and Asn123-Thr124 bonds in κ-CN, as determined by mass spectrometry. MCE-G165A showed different hydrolysis sites in casein, leading to various functional peptides. Feasible methods for obtaining MCEs suitable as calf rennet substitutes are presented.


Assuntos
Bacillus licheniformis/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Caseínas/química , Quimosina/química , Quimosina/genética , Leite/química , Sequência de Aminoácidos , Animais , Proteínas de Bactérias/metabolismo , Caseínas/metabolismo , Bovinos , Queijo/análise , Queijo/microbiologia , Quimosina/metabolismo , Hidrólise , Engenharia de Proteínas , Proteólise , Alinhamento de Sequência
15.
Artigo em Inglês | MEDLINE | ID: mdl-31553689

RESUMO

Iodised salt (supplemented with potassium iodide) is the primary source of iodine in Switzerland, but it is rarely used in the manufacture of cheese. In the present study, the diffusion of iodide and chloride in experimentally produced soft, semi-hard and hard cheeses was investigated after brine-salting and subsequent ripening with iodised or non-iodised salt. Diffusion of iodide (I-) and chloride (Cl-) into the cheeses was monitored by zonal analyses at different times of ripening. The concurrent diffusion of the two ions in the aqueous phase of cheeses was modelled using Fick's law and the apparent diffusion coefficients (Dapp) were determined. The results showed that iodide diffuses more slowly into the interior of the cheeses than chloride. Although the ripened cheeses still showed a concentration gradient between rind and centre, an average increase of 402 ± 30 µg kg-1 iodine was achieved in the edible part of the cheeses treated with iodised salt. Based on a national food survey, the hypothetical contribution of cheese to the dietary iodine intake was estimated. If cheese was produced with iodised salt, it would cover approximately 10% of the recommended daily iodine intake (150 µg d-1). Therefore, the use of iodised salt in cheese production would make an important contribution to a iodine supply for population groupswith borderline iodine deficiency.


Assuntos
Queijo/análise , Contaminação de Alimentos/análise , Iodo/análise , Sais/química , Difusão
16.
J Dairy Sci ; 102(11): 9639-9650, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31477286

RESUMO

To determine the key aroma compounds in Chinese milk fan cheese, samples from 6 of the most popular handmade milk fan workshops in Yunnan province of China were analyzed by gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O), sensory evaluation, aroma recombination and omission experiments. Seventy-one aroma compounds were identified by GC-MS, and 31 odor-active compounds were detected by GC-O. The relationships between the 31 odor-active compounds and 10 sensory evaluation properties were explored by partial least squares discriminant analysis. The results identified 23 initial key aroma compounds, which were used to simulate the aroma profile of milk fan in aroma recombination experiments. Aroma omission experiments identified propanoic acid, butanoic acid, octanoic acid, octanal, nonanal, 2-nonanone, and ethyl hexanoate as the key aroma compounds. Propanoic acid and butanoic acid contributed to cheese and rancid aromas, octanal and nonanal to the fat aroma, octanoic acid and 2-nonanone to the cheese aroma, and ethyl hexanoate to the fruity aroma of milk fan.


Assuntos
Leite/química , Odorantes/análise , Aldeídos/análise , Animais , Bovinos , Queijo/análise , China , Cromatografia Gasosa-Espectrometria de Massas/métodos , Cetonas/análise , Análise dos Mínimos Quadrados , Olfatometria/métodos
17.
J Dairy Sci ; 102(11): 9622-9638, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31477307

RESUMO

Near-infrared spectroscopy (NIRS) has been widely used to determine various composition traits of many dairy products in the industry. In the last few years, near-infrared (NIR) instruments have become more and more accessible, and now, portable devices can be easily used in the field, allowing the direct measurement of important quality traits. However, the comparison of the predictive performances of different NIR instruments is not simple, and the literature is lacking. These instruments may use different wavelength intervals and calibration procedures, making it difficult to establish whether differences are due to the spectral interval, the chemometric approach, or the instrument's technology. Hence, the aims of this study were (1) to evaluate the prediction accuracy of chemical contents (5 traits), pH, texture (2 traits), and color (5 traits) of 37 categories of cheese; (2) to compare 3 instruments [2 benchtop, working in reflectance (R) and transmittance (T) mode (NIRS-R and NIRS-T, respectively) and 1 portable device (VisNIRS-R)], using their entire spectral ranges (1100-2498, 850-1048, and 350-1830 nm, respectively, for NIRS-R, NIRS-T and VisNIRS-R); (3) to examine different wavelength intervals of the spectrum within instrument, comparing also the common intervals among the 3 instruments; and (4) to determine the presence of bias in predicted traits for specific cheese categories. A Bayesian approach was used to develop 8 calibration models for each of 13 traits. This study confirmed that NIR spectroscopy can be used to predict the chemical composition of a large number of different cheeses, whereas pH and texture traits were poorly predicted. Color showed variable predictability, according to the trait considered, the instrument used, and, within instrument, according to the wavelength intervals. The predictive performance of the VisNIRS-R portable device was generally better than the 2 laboratory NIRS instruments, whether with the entire spectrum or selected intervals. The VisNIRS-R was found suitable for analyzing chemical composition in real time, without the need for sample uptake and processing. Our results also indicated that instrument technology is much more important than the NIR spectral range for accurate prediction equations, but the visible range is useful when predicting color traits, other than lightness. Specifically for certain categories (i.e., caprine, moldy, and fresh cheeses), dedicated calibrations seem to be needed to obtain unbiased and more accurate results.


Assuntos
Queijo/análise , Espectroscopia de Luz Próxima ao Infravermelho , Animais , Teorema de Bayes , Viés , Calibragem , Cor , Cabras , Fenótipo , Reprodutibilidade dos Testes , Espectroscopia de Luz Próxima ao Infravermelho/métodos
18.
Nutrients ; 11(9)2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31514309

RESUMO

There is mounting evidence that the consumption of fermented dairy products such as cheese and yoghurt is associated with a reduced risk of type II diabetes. This effect is greater than in fresh milk and differs between cheese and yoghurt. However, the molecular components responsible for the effect are not known. We tested the hypothesis that the lipid and/or glyceride profiles of yoghurts and cheeses are distinct from one another and fresh milk. We developed a novel sample preparation technique for high-fat samples that can be used with Direct Infusion-Mass Spectrometry. We found that the lipid and glyceride profiles of cheddars from the UK, Ireland and France, and hard cheeses from Sweden and Italy were similar to one another but distinct from unfermented dairy products. The lipid and glyceride profile of yoghurts was varied and included types that may be similar to fresh milk. Several odd-chain-containing triglycerides were more abundant, while a variety of others were less abundant, in fermented milk samples. Phosphatidylcholines and phosphatidylethanolamines were more abundant in cheeses, with evidence that the phosphatidylethanomine profile is re-modelled in a way that reflects the bacterial cell envelope. We concluded that a combination of microorganismal metabolism, concentration of the lipid/glyceride fraction and oxidation during fermentation contribute to the observed lipid profile if fermented dairy foods. These differences in the lipid and glyceride profile provide a new avenue for understanding why different fermented dairy foods show a different association with reduced disease risk compared to unfermented dairy.


Assuntos
Queijo/análise , Fermentação , Glicerídeos/análise , Lipídeos/análise , Leite/química , Valor Nutritivo , Iogurte/análise , Animais , Queijo/microbiologia , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/prevenção & controle , Microbiologia de Alimentos , Humanos , Espectrometria de Massas , Leite/microbiologia , Iogurte/microbiologia
19.
Lett Appl Microbiol ; 69(4): 230-236, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31381169

RESUMO

This study evaluated the survival responses of Listeria monocytogenes strains (individually and mixed) in a soft lactic cheese following acid and salt stress exposures. The Weibull and log-linear with tail models were used to predict the survival responses of the pathogen in the cheese stored at 4°C for 15 days. Both models showed a good prediction accuracy for stressed L. monocytogenes cells (Af = 1·00) and higher prediction errors (Af = 1·12-1·14) for nonstressed cells. The inactivation rates (δ (d) and kmax (d-1 )) were significantly lower (P < 0·05) for cells subjected to stress exposure indicating the enhanced tolerance to food stress. However, while enhanced tolerance appeared to be the main effect of stress pre-exposure, in one susceptible strain (69), stress exposure led to higher rates of inactivation. When introduced into the food as mixed strains, one strain out-lived others and remained as the sole survivor. Such strains that perhaps have a predilection for the food environment can provide more cautious estimates of kinetic parameters for predicting L. monocytogenes responses in foods especially if their stress-hardened tolerant cells are used. SIGNIFICANCE AND IMPACT OF THE STUDY: The ability to predict the growth and survival of Listeria monocytogenes in contaminated RTE foods is essential for listeriosis risk assessment. The results of this study provided valuable information on the kinetic parameters of survival of some L. monocytogenes strains found within the South African food environment. In addition to showing differences in the survival responses among strains, the study also showed the importance of the pre-contamination state of the cells in influencing survival kinetics.


Assuntos
Queijo/microbiologia , Ácido Láctico/farmacologia , Listeria monocytogenes/crescimento & desenvolvimento , Listeriose/epidemiologia , Cloreto de Sódio/farmacologia , Queijo/análise , Microbiologia de Alimentos , Medição de Risco , Tolerância ao Sal/fisiologia , África do Sul/epidemiologia
20.
Bioelectrochemistry ; 130: 107200, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31382227

RESUMO

In this study, a microbial electrochemical system (MES) was employed to investigate the effect of isoelectric point (IEP) on cheese whey wastewater treatment. The experiments were carried out in a bioreactor equipped with a semicircular carbon cloth and stainless steel electrodes as anode and cathode, respectively. The effects of IEP, whey protein concentration, electrical current, and time were studied. The IEP of the whey protein was determined at pH 5.9. The optimum electrical current was obtained at 6 mA for synthetic cheese whey wastewater. The results of rotary exponential doping showed that the third structure of proteins chenges to the second structure at the IEP. The highest protein removal (98%) was obtained at pH 6. The results showed that 76%, 83%, and 98% protein removal were achieved at 2, 4, and 8 h, respectively.


Assuntos
Reatores Biológicos/microbiologia , Águas Residuárias/análise , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/instrumentação , Proteínas do Soro do Leite/isolamento & purificação , Análise da Demanda Biológica de Oxigênio , Queijo/análise , Desenho de Equipamento , Tecnologia de Alimentos , Ponto Isoelétrico
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