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1.
Food Chem ; 366: 130606, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34311233

RESUMO

A natamycin-based non-migratory antimicrobial packaging for extending shelf-life of yogurt drink (Doogh) was developed. Firstly, the surface of low-density polyethylene film (LDPE) was modified with acrylic acid at different times of UV exposure (0-10 min) to produce carboxylic functional groups. Then, natamycin was applied to the UV-treated films to bind covalently with the pendent functional groups. The maximum grafting efficiency (81.96%) was obtained for the 6 min treated film. Moreover, surface properties of films were evaluated by Attenuated Total Reflectance/Fourier Transfer Infrared Spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). Antifungal activity of different treatments of natamycin grafted film was evaluated against two common spoilage yeasts of Doogh including Rhodotorula mucilaginosa and Candida parapsilosis. Results showed that 6 min treated film provides maximum anti-yeast activity and can be applied to control fungal growth in Doogh. Natamycin-grafted film postponed the yeast spoilage in Doogh and prolonged its shelf-life to 23 days.


Assuntos
Anti-Infecciosos , Natamicina , Anti-Infecciosos/farmacologia , Embalagem de Alimentos , Rhodotorula , Iogurte
2.
Talanta ; 236: 122833, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34635223

RESUMO

A dynamic pH junction was used in capillary electrophoresis (CE-DAD) to on-line preconcentrate, separate, and determine trace amounts of sulfonamide antibiotics (SAs) in milk and yoghurt samples in this study. A sample matrix with 0.15% acetic acid and 10% methanol (MeOH) at a pH of 4.0, and a background electrolyte (BGE) that contained 35 mM sodium citrate with 10% MeOH at a pH of 8.5, and an acidic barrage of 0.4% acetic acid with 10% MeOH at a pH of 2.5 were utilised to achieve a stacking effect for SAs through a dynamic pH junction. Under optimised conditions, the proposed preconcentration method showed good linearity (30-500 ng/mL, r2 ≥ 0.9940), low limits of detection (LODs) of 4.1-6.3 ng/mL, and acceptable analytes recovery (81.2-106.9%) with relative standard deviations (RSDs) within 5.3-13.7 (n = 9). The limits of quantification (LOQs) were below the maximum residue limit approved by the European Union (EU) in this type of matrices. Sensitivity enhancement factors of up to 129 were reached with the optimised dynamic pH junction using CE with a diode array detector (DAD). The method was used to determine SAs in fresh milk, low-fat milk, full-cream milk, and yoghurt samples.


Assuntos
Antibacterianos , Iogurte , Animais , Eletroforese Capilar , Concentração de Íons de Hidrogênio , Leite , Sulfonamidas
3.
Adv Nutr ; 12(Suppl 1): 1S-13S, 2021 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-34632478

RESUMO

Systemic chronic inflammation may be a contributing factor to many noncommunicable diseases, including diabetes, cardiovascular disease, and obesity. With the rapid rise of these conditions, identifying the causes of and treatment for chronic inflammation is an important research priority, especially with regard to modifiable lifestyle factors such as diet. An emerging body of evidence indicates that consuming certain foods, including dairy foods like milk, cheese, and yogurt, may be linked to a decreased risk for inflammation. To discuss both broader research on diet and inflammation as well as research on links between individual foods and inflammation, the National Dairy Council sponsored a satellite session entitled "Exploring the Links between Diet and Inflammation: Dairy Foods as Case Studies" at the American Society for Nutrition's 2020 LIVE ONLINE Conference. This article, a review based on the topics discussed during that session, explores the links between diet and inflammation, focusing most closely on the relations between intake of dairy fat and dairy foods like milk, cheese, and yogurt, and biomarkers of inflammation from clinical trials. While there is currently insufficient evidence to prove an "anti-inflammatory" effect of dairy foods, the substantial body of clinical research discussed in this review indicates that dairy foods do not increase concentrations of biomarkers of chronic systemic inflammation.


Assuntos
Queijo , Laticínios , Animais , Dieta , Humanos , Inflamação , Leite , Fatores de Risco , Iogurte
4.
Molecules ; 26(16)2021 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-34443340

RESUMO

The oat ß-glucan (OG) was added into set-type yogurt as a functional ingredient, in order to evaluate effects on the rheological characteristics and microstructure of set-type yogurt. When the OG concentration increased from 0 to 0.3%, the WHC gradually increased. At 0.3% OG, the set-type yogurt had the highest WHC of 94.67%. Additionally, the WHC continuously decreased, reaching the lowest WHC (about 80%) at 0.5% OG. When 0.3% OG was added, the highest score of sensory evaluation was about 85. The rheological result showed that the fermentation process went through the changes as follows: solid → liquid → solid → liquid. The addition of 0.3% OG decreased the fermentation time of set-type yogurt by about 16 min, making yogurt more inclined to be liquid. The acidity of set-type yogurt with OG was slightly higher. The result of microstructure showed that the addition of OG destroyed the three-dimensional network structure of yogurt, and some spherical aggregate particles could be clearly observed at 0.3% OG. Overall, this study provided a theoretical basis for the application of OG in set-type yogurt.


Assuntos
Avena/química , Reologia , Iogurte/análise , beta-Glucanas/farmacologia , Fermentação/efeitos dos fármacos
5.
Molecules ; 26(16)2021 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-34443359

RESUMO

Beet has been used as an ingredient for functional foods due to its high antioxidant activity, thanks to the betalains it contains. The effects of the addition of beet extract (liquid and lyophilized) on the physicochemical characteristics, color, antioxidant activity (AA), total betalains (TB), total polyphenols (TP), and total protein concentration (TPC) were evaluated on stirred yogurt. The treatments (T1-yogurt natural, T2-yogurt added with beet juice, T3-added extract of beet encapsulated with maltodextrin, and T4-yogurt added with extract of beet encapsulated with inulin) exhibited results with significant differences (p < 0.05). The highest TB content was observed in T2 (209.49 ± 14.91), followed by T3 (18.65 ± 1.01) and later T4 (12.96 ± 0.55). The highest AA was observed on T2 after 14 days (ABTS˙ 0.819 mM TE/100 g and DPPH˙ 0.343 mM TE/100 g), and the lowest was found on T1 at day 14 (ABTS˙ 0.526 mM TE/100 g and DPPH˙ 0.094 mM TE/100 g). A high content of TP was observed (7.13 to 9.79 mg GAE/g). The TPC varied between 11.38 to 12.56 µg/mL. The addition of beet extract significantly increased AA in yogurt, betalains being the main compounds responsible for that bioactivity.


Assuntos
Antioxidantes/química , Beta vulgaris/química , Extratos Vegetais/química , Iogurte/análise , Cápsulas , Fenômenos Químicos , Manipulação de Alimentos , Fenômenos Mecânicos
6.
Food Res Int ; 147: 110517, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34399495

RESUMO

The potential application of 3D printing technology in creating protein-rich desserts with multisensory design was investigated. Yoghurt-gel inks were formulated by varying the concentration of gelatine and whey protein isolate (WPI). Assessment of rheological and textural properties prior to printing, showed that an increase of gelatine concentration from 7.5 to 12.5% w/w increased the yield stress, storage modulus, loss modulus, firmness, and resilience of yoghurt gels. Addition of 12% WPI reduced these effects; creating softer gels with reduced resilience. However, these gels showed stable shape after printing, especially in formulations with higher gelatine concentrations. The changes in textural properties caused by the extrusion process need to be considered when designing yoghurt gels, as a significant reduction in firmness and resilience and an increase in adhesiveness were observed after 3D printing. The more stable and well-shaped 3D printed yoghurt gels were obtained by the combined effect of WPI and gelatine which provided a good balance of appearance, taste, flavour, and mouthfeel attributes evaluated by a trained sensory panel. A consumer study performed with thirty healthy adults showed the potential to improve sensory acceptance through the creation of multisensory layered design.


Assuntos
Gelatina , Iogurte , Géis , Humanos , Impressão Tridimensional , Reologia , Iogurte/análise
7.
Molecules ; 26(15)2021 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-34361753

RESUMO

The popularity and consumption of fermented milk products are growing. On the other hand, consumers are interested in health-promoting and functional foods. Fermented milk products are an excellent matrix for the incorporation of bioactive ingredients, making them functional foods. To overcome the instability or low solubility of many bioactive ingredients under various environmental conditions, the encapsulation approach was developed. This review analyzes the fortification of three fermented milk products, i.e., yogurt, cheese, and kefir with bioactive ingredients. The encapsulation methods and techniques alongside the encapsulant materials for carotenoids, phenolic compounds, omega-3, probiotics, and other micronutrients are discussed. The effect of encapsulation on the properties of bioactive ingredients themselves and on textural and sensory properties of fermented milk products is also presented.


Assuntos
Queijo/análise , Tecnologia de Alimentos/métodos , Alimento Funcional/análise , Kefir/análise , Leite/metabolismo , Iogurte/análise , Animais , Carotenoides/administração & dosagem , Carotenoides/química , Ácidos Graxos Ômega-3/administração & dosagem , Fermentação , Aditivos Alimentares/administração & dosagem , Humanos , Lactobacillaceae/fisiologia , Micronutrientes/administração & dosagem , Leite/química , Leite/microbiologia , Fenóis/administração & dosagem , Fenóis/química , Probióticos/administração & dosagem
8.
Nutrients ; 13(8)2021 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-34444974

RESUMO

The administration of broad-spectrum antibiotics is often associated with antibiotic-associated diarrhea (AAD), and impacts gastrointestinal tract homeostasis, as evidenced by the following: (a) an overall reduction in both the numbers and diversity of the gut microbiota, and (b) decreased short-chain fatty acid (SCFA) production. Evidence in humans that probiotics may enhance the recovery of microbiota populations after antibiotic treatment is equivocal, and few studies have addressed if probiotics improve the recovery of microbial metabolic function. Our aim was to determine if Bifidobacterium animalis subsp. lactis BB-12 (BB-12)-containing yogurt could protect against antibiotic-induced fecal SCFA and microbiota composition disruptions. We conducted a randomized, allocation-concealed, controlled trial of amoxicillin/clavulanate administration (days 1-7), in conjunction with either BB-12-containing or control yogurt (days 1-14). We measured the fecal levels of SCFAs and bacterial composition at baseline and days 7, 14, 21, and 30. Forty-two participants were randomly assigned to the BB-12 group, and 20 participants to the control group. Antibiotic treatment suppressed the fecal acetate levels in both the control and probiotic groups. Following the cessation of antibiotics, the fecal acetate levels in the probiotic group increased over the remainder of the study and returned to the baseline levels on day 30 (-1.6% baseline), whereas, in the control group, the acetate levels remained suppressed. Further, antibiotic treatment reduced the Shannon diversity of the gut microbiota, for all the study participants at day 7. The magnitude of this change was larger and more sustained in the control group compared to the probiotic group, which is consistent with the hypothesis that BB-12 enhanced microbiota recovery. There were no significant baseline clinical differences between the two groups. Concurrent administration of amoxicillin/clavulanate and BB-12 yogurt, to healthy subjects, was associated with a significantly smaller decrease in the fecal SCFA levels and a more stable taxonomic profile of the microbiota over time than the control group.


Assuntos
Antibacterianos/efeitos adversos , Bifidobacterium animalis/metabolismo , Ácidos Graxos Voláteis/metabolismo , Fezes , Microbioma Gastrointestinal , Trato Gastrointestinal/microbiologia , Probióticos/uso terapêutico , Adolescente , Adulto , Idoso , Colo , Diarreia/etiologia , Diarreia/microbiologia , Diarreia/prevenção & controle , Fezes/química , Fezes/microbiologia , Trato Gastrointestinal/metabolismo , Humanos , Pessoa de Meia-Idade , Iogurte/microbiologia , Adulto Jovem
9.
J Dairy Sci ; 104(10): 10528-10539, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34334203

RESUMO

The growth behaviors and metabolomic profiles in yogurts induced by multistrain probiotics of Lactobacillus casei Zhang (LCZ) and Bifidobacterium lactis V9 (V9) at the fermentation termination and 10 d of storage at 4°C under different fermentation temperatures (37°C and 42°C) were compared using metabolomics based on liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry. The growths of LCZ and V9 were affected by fermentation temperatures; the viable cell density of LCZ was higher at 37°C than that at 42°C; however, V9 was higher at 42°C. Multistrain probiotics had higher contribution to the changes in volatile and nonvolatile metabolomic profiles at 42°C than those at 37°C. At fermentation termination, there were 2 common enriched pathways increased by multistrain probiotics at 37°C and 42°C, which were biosynthesis of peptides and amino- and nucleotide-sugar metabolism. At 10 d of storage, 4 common increased enriched pathways were alanine, aspartate and glutamate metabolism; tyrosine metabolism; valine, leucine, and isoleucine degradation; and valine, leucine, and isoleucine biosynthesis. This work provided a detailed insight into different effects of different multistrain probiotics of LCZ and V9 fermentation temperatures on the growth behaviors and volatile and nonvolatile metabolomic profiles of yogurts.


Assuntos
Bifidobacterium animalis , Lactobacillus casei , Probióticos , Animais , Fermentação , Metabolômica , Leite , Temperatura , Iogurte/análise
10.
J Food Sci ; 86(9): 3896-3908, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34383307

RESUMO

Greek-style yogurt (GSY) has gained reputation as a healthy food because of its high protein content. Vaccinium meridionale S. is a bilberry with a high content of bioactive phytochemicals, whose vaccinium meridionale pomace (VMP) represents about 20% of the fruit weight. However, this byproduct is normally discarded as waste. In this study, VMP was used as a natural colorant in GSY. Coloring before or after the fermentation process resulted in significant increase in anthocyanins, total phenolics content, antioxidant activity, conjugated linoleic acid, and sensory acceptance. These results indicate that VMP is a potential natural, eco-friendly, and functional colorant to improve the nutritional value of GSY. PRACTICAL APPLICATION: Vaccinium meridionale pomace is a waste product with potential to be utilized as a natural, eco-friendly, and functional colorant to obtain value-added Greek-style yogurt. Besides providing bioactive compounds and natural color, this pomace improves the nutritional value, sensory acceptance, and functional properties of Greek yogurt.


Assuntos
Corantes de Alimentos , Vaccinium , Iogurte , Antocianinas/química , Corantes de Alimentos/química , Corantes de Alimentos/normas , Frutas/química , Vaccinium/química , Iogurte/análise , Iogurte/normas
11.
Biomed Res Int ; 2021: 1057531, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34435040

RESUMO

Nowadays, production of functional foods has become very essential. Inulin is one of the most functional hydrocolloid compounds used in such products. In the present study, the production of a synbiotic yogurt containing 1, 2.5, and 5% (w/v) inulin has been investigated. The yogurt was fermented with Lactobacillus brevis PML1 derived from Tarkhineh, an Iranian cereal-dairy fermented food. Furthermore, the physicochemical properties, antioxidant activity, sensory attributes, and microbial viability properties were investigated on the 0th, 7th, and 14th days of storage after fermentation. The viable cells of L. brevis PML1 reached 108 CFU/g, and the product resisted to simulated digestive juices. Moreover, the synbiotic yogurt impressively increased the production of antimicrobial compounds and had the most profound antimicrobial effect on S. typhimurium. The physiochemical properties were in the normal range, and the fat content of the synbiotic yogurt was reduced remarkably. The antioxidant capacity of the fermented yogurt was significantly increased (p < 0.05), which was equal to those of DPPH (69.18 ± 1.00%) and BHA (89.16 ± 2.00%). The viability of L. brevis PML1 was increased during storage. Sensory analysis showed that there were significant differences in terms of the impressive parameters between the samples and the control (p < 0.05). Addition of 2.5% inulin not only improved the physical properties but also retained the viability of the probiotic after 14 days of storage, in addition to the viability of L. brevis with a viability count above 6 log CFU/g in the yogurt. Therefore, a novel synbiotic product containing L. brevis PML1, which can exert the desired properties, can be used as a suitable carrier for the delivery of the probiotic strain, exerting its beneficial health effects.


Assuntos
Laticínios/microbiologia , Grão Comestível/microbiologia , Lactobacillus brevis/metabolismo , Simbióticos/análise , Iogurte/microbiologia , Antioxidantes/análise , Fermentação , Inulina/análise , Irã (Geográfico) , Lactobacillus brevis/crescimento & desenvolvimento , Lactobacillus brevis/isolamento & purificação , Viabilidade Microbiana , Iogurte/análise
12.
An Acad Bras Cienc ; 93(4): e20200002, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34378758

RESUMO

In the current study, twenty-eight bacterial strains were isolated from home-made yogurt samples from Agri Province, Turkey. The bacterial strains were identified by conventional and molecular techniques. Among the twenty- eight isolates, seventeen isolates were identified according to the 16 S rDNA region and determined to belong to five different genus including Sphingomonas (8 isolates), Burkholderia (5 isolates), Lactobacillus (2 isolates), Lactococcus (1 isolate), Staphylococcus (1 isolate). In this study, the presence of Burkholderia in home-made yogurt samples were reported for the first time, whereas Sphingomonas was detected for the second time. We also investigated the carbonate (CaCO3 and MgCO3) and silicate ( CaSiO3 and MgSiO3) dissolving potential of seventeen bacterial isolates. Among these seventeen bacterial isolates, fifteen bacterial isolates have CaCO3-dissolving and 10 bacterial isolates have MgCO3-dissolving potential. The silicates dissolution ability was relatively less than that of carbonates dissolving. We observed that six bacterial isolates have CaSiO3 and only two bacterial isolates have MgSiO3 dissolution abilities. In conclusion, this work clearly shows the diversity of bacteria existing in fermented cow milk samples in Agri Province, Turkey, which could be considered as valuable sources for lactic acid bacteria (LAB) isolation and further probiotic potential.


Assuntos
Probióticos , Iogurte , Animais , Carbonatos , Bovinos , Feminino , Lactobacillus , Silicatos
13.
Nutrients ; 13(6)2021 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-34198901

RESUMO

The aim of our research was to assess whether and to what extent the perceived change in the content of selected ingredients in dairy products is important for Polish consumers in accepting the enhancement of the health benefits of dairy products, including yogurt. The data were collected using a CAPI (Computer Assisted Personal Interview) survey on a sample of 983 consumers. The logistic regression model was used to predict the behavior of consumers associated with their willingness to accept the health aspects of improving dairy products. The results indicated that changes in the level of selected ingredients enhanced the willingness to accept increasing the health value of the product. The socio-demographic characteristics of the participants were not associated with the degree of their willingness to accept the improvement of the perceived health attributes. Practitioners in the dairy industry and policy makers can benefit from these results. When designing food products, it is worth focusing on increasing the nutritional value and enhancing the health value of food that is perceived by consumers as generally possessing positive health benefits, rather than on food that is perceived by them as possessing negative qualities.


Assuntos
Comportamento do Consumidor , Laticínios , Preferências Alimentares/psicologia , Comportamentos Relacionados com a Saúde , Opinião Pública , Adulto , Comportamento de Escolha , Feminino , Alimentos Fortificados , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Valor Nutritivo , Percepção , Polônia , Análise de Componente Principal , Inquéritos e Questionários , Iogurte , Adulto Jovem
14.
Waste Manag ; 131: 403-411, 2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-34247138

RESUMO

Converting wastes to valuable products is the main target for many kinds of research nowadays. Wastes represent an environmental problem and getting rid of it is not easy and causes pollution. Accordingly, this study offers production of the valuable enzyme ß-galactosidase using rice straw and orange peel as the main medium constituents. ß-galactosidase converts lactose to glucose and galactose which are simple sugars and can be fermented easily by lactose-intolerant people who represent more than 50% of the world's population. It was produced by Lactobacillus paracasei, a series isolated from fermented milk, identified using 16S ribosomal RNA gene partial sequence and had the accession number MK852178. Plackett-Burman (PB) and Central Composite (CCD) Designs optimized the production scoring 1.683(10)6 U/ml with a difference five times higher than the non-optimized medium. The addition of 0.3 or 0.6% of ß-galactosidase serves as a good fortification for manufacturing nutritional and therapeutic low-lactose yogurt with no significant differences in total protein, total solids, fat, and ash between control and all treatments. The chemical, rheological and sensory properties of the final produced yogurt were evaluated during storage periods up to 9 days at 5 °C. In conclusion, L. paracasei MK852178 ß-galactosidase is a promising additive in manufacturing low lactose yogurt for lactose-intolerant people since it reduces the lactose content and doesn't influence the chemical and sensory properties.


Assuntos
Citrus sinensis , Lactobacillus paracasei , Oryza , beta-Galactosidase/biossíntese , Animais , Lactase , Lactose , Leite , Iogurte
15.
Biomed Res Int ; 2021: 5576873, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34327229

RESUMO

Staphylococcus aureus is a contagious pathogen that can cause various diseases in both humans and animals. Antimicrobial-resistant S. aureus is becoming an extremely important global health problem. A cross-sectional study was conducted from December 2019 to May 2020 to assess the occurrence of S. aureus and its antimicrobial susceptibility profiles in milk and traditionally processed dairy products in selected subcities of Addis Ababa. A total of 255 dairy product samples (175 raw milk and 80 traditionally processed dairy products) were collected from farms and retail markets. Samples were cultured for S. aureus according to standard microbiology techniques, and the Kirby-Bauer disk diffusion method was used to assess antimicrobial susceptibility of isolates to a panel of 12 antimicrobials. Susceptibility to methicillin was determined based on the sensitivity of isolates to cefoxitin, and resistant isolates were investigated for the presence of mecA and mecC genes using PCR. Staphylococcus aureus was isolated from 43 (24.6%) of milk, 7 (17.5%) of yogurt, and 2 (5%) of cottage cheese. A significantly higher rate of contamination with S. aureus was recorded among milk samples compared to yogurt and cottage cheese (p = 0.019). Out of 52 S. aureus isolates investigated for susceptibility to 12 antimicrobials, 49 (94.2%) of the isolates were resistant to ampicillin and 42 (80.8%) to amoxicillin+clavulanic acid. Twenty (38.5%) of the isolates were methicillin-resistant S. aureus (MRSA) based on susceptibility to cefoxitin. However, only one of these isolates (5%) was positive for mecA gene, and none of them were positive for the mecC gene. There was no significant difference (p > 0.05) in the rate of occurrence of MRSA among isolates from different sources. In conclusion, this study demonstrated a significant level of contamination of milk and dairy products with S. aureus and most isolates were multidrug resistant. The occurrence of MRSA in raw milk and dairy products signifies a serious public health threat as the practice of consuming raw dairy products in the study area is widespread. The lack of agreement between phenotypic and genotypic detection of MRSA suggests the need for further study to identify the genetic basis for the observed resistance phenotype.


Assuntos
Anti-Infecciosos/farmacologia , Laticínios/microbiologia , Leite/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Animais , Queijo/microbiologia , Etiópia , Geografia , Testes de Sensibilidade Microbiana , Prevalência , Staphylococcus aureus/isolamento & purificação , Iogurte/microbiologia
16.
J Dairy Sci ; 104(10): 10485-10499, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34275633

RESUMO

Consumers are not always ready to compromise on the loss of texture and increased syneresis that nonfat stirred yogurts display compared with yogurts that contain fat. In this study, we investigated milk protein composition and smoothing temperature as a means to control nonfat yogurt microstructure, textural properties, and syneresis. Yogurts were prepared with different ratios of casein to whey protein (R1.5, R2.8, and R3.9). Yogurts were pumped through a smoothing pilot system comprising a plate heat exchanger set at 15, 20, or 25°C and then stored at 4°C until analysis (d 1, 9, and 23). Yogurt particle size and firmness were measured. Yogurt syneresis and water mobility were determined, respectively, by centrifugation and time domain low-frequency proton nuclear magnetic resonance (1H-LF-NMR). Increasing the smoothing temperature increased gel firmness and microgel (dense protein aggregates) sizes independently of the whey protein content. Also, yogurt microgel sizes changed with storage time, but the evolution pattern depended on protein ratio. Yogurt R1.5 showed the largest particles, and their sizes increased with storage, whereas R2.8 and R3.9 had smaller microgels, and R3.9 did not show any increase in microgel size during storage. Micrographs showed a heterogeneous gel with the empty area occupied by serum for R1.5, whereas R2.8 and R3.9 showed fewer serum zones and a more disrupted gel embedding microgels. Induced syneresis reduced with greater whey protein content and time of storage. This is in agreement with 1H-LF-NMR showing less bulk water mobility with increasing whey protein content during storage. However, 1H-LF-RMN revealed higher values of spontaneous serum separation during storage for R1.5 and R3.9 yogurts, whereas these were lower and stable for R2.8 yogurt. Microgels play an important structural role in yogurt textural attributes, and their characteristics are modulated by whey protein content and smoothing temperature. Optimization of these parameters may help improve nonfat stirred dairy gel.


Assuntos
Caseínas , Iogurte , Animais , Manipulação de Alimentos , Proteínas do Leite/análise , Temperatura , Proteínas do Soro do Leite , Iogurte/análise
17.
Food Chem ; 365: 130513, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34247045

RESUMO

This research aimed to biosynthesizing zinc oxide nanoparticles (ZnO-NPs) using lactobacilli strains. All tested lactobacilli able to biosynthesis ZnO-NPs indicated by white precipitates. The characteristics of the biosynthesis ZnO-NPs from Lactobacillus gasseri were studied using UV-visible spectroscopy, TEM, SEM, DLS, FT-IR, XRD, and antimicrobial activity. The characteristic examination depicted cubic structures, pure and spherical ZnO-NPs with a diameter size of 22 nm. Antimicrobial study of ZnO-NPs displayed better higher antimicrobial activity on food pathogens in a dose-dependent manner. Moreover, integrated biosynthesis ZnO-NPs in yogurt positively affected the shelf life of yogurt during storage for four weeks without changes in the sensory evaluation. The microbiological population of fortified yogurt significantly reduced during storage than control. But chemically evaluation of fortified yogurt indicated an increase in dry matter, protein, and ash content than control. The achieved results suggested that the low amount of biosynthesized ZnO-NPs lead to the development of properties of integrated yogurt. Furthermore, the biosynthesized ZnO-NPs additive to yogurt could be a good food source for groups suffering from zinc deficiency such as the elderly groups or vegetarians who do not eat meat and at risk of zinc inadequacy.


Assuntos
Lactobacillus gasseri , Nanopartículas Metálicas , Nanopartículas , Óxido de Zinco , Idoso , Antibacterianos/farmacologia , Humanos , Testes de Sensibilidade Microbiana , Espectroscopia de Infravermelho com Transformada de Fourier , Iogurte
18.
J Dairy Sci ; 104(9): 9617-9626, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34099292

RESUMO

Yogurt is traditionally fermented by a symbiotic starter culture of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus. These bacteria exchange metabolites with each other to meet their nutritional demands during protocooperation, resulting in a shorter fermentation time. In this study, we investigated whether fumaric acid functions as a symbiotic agent to promote the growth of Lb. bulgaricus by evaluating 8 strains of Lb. bulgaricus and 7 strains of Strep. thermophilus. All the tested Lb. bulgaricus strains metabolized the added fumaric acid into succinic acid during monoculture in milk, and 6 strains (75%) showed shorter fermentation time compared with the control. The addition of malic acid showed similar trends as that of fumaric acid, indicating that the reverse tricarboxylic acid cycle was functioning in Lb. bulgaricus. All 7 Strep. thermophilus strains tested produced fumaric acid during monoculture in milk. Further, in Lb. bulgaricus 2038, the gene expression of fumarate reductase that converts fumaric acid to succinic acid, was higher in the coculture with Strep. thermophilus 1131 than in the monoculture. These findings indicate that fumaric acid produced by Strep. thermophilus can function as a symbiotic substance during yogurt fermentation to stimulate the growth of Lb. bulgaricus.


Assuntos
Lactobacillus delbrueckii , Animais , Fermentação , Fumaratos , Streptococcus thermophilus , Iogurte
19.
J Dairy Sci ; 104(9): 9570-9582, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34127268

RESUMO

Yeast spoilage of fermented dairy products causes challenges for the dairy industry, including economic losses due to wasted product. Food cultures with bioprotective effects are becoming more widely used to help ensure product quality throughout product shelf life. To assist the dairy industry when evaluating product quality throughout shelf life and the effect of bioprotective cultures, we aimed to build stochastic models that provide reliable predictions of yeast spoilage in yogurt with and without bioprotective culture. Growth characterizations of Debaryomyces hansenii, Yarrowia lipolytica, Saccharomyces cerevisiae, and Kluyveromyces marxianus at storage temperatures of 7, 12, and 16°C during a 30-d storage period were conducted in yogurt with and without a bioprotective culture containing Lacticaseibacillus rhamnosus strains. The kinetic growth parameters were calculated using the Buchanan growth model, and these parameters were used as baseline values in Monte Carlo models to translate the yeast growth into spoilage levels. The models were developed using 100,000 simulations and they predicted yeast spoilage levels in yogurt by the 4 yeast types. Each modeled yogurt batch was set to be contaminated with yeast at a concentration drawn from a normal distribution with a mean of 1 log10 cfu/mL and standard deviation of 1 log10 cfu/mL and stored for 30 d at a temperature drawn from a normal distribution with a mean of 6.1°C and a standard deviation of 2.8°C. Considering a spoilage level of 5 log10 cfu/mL, the predicted number of spoiled samples was reduced 3-fold during the first 10 d and by 2-fold at the end of shelf life when a bioprotective culture was added to the yogurt. The models were evaluated by sensitivity analyses, where the main effect factors were maximum yeast population, storage temperature, and yeast strain. The models were validated by comparing the model output to actual observed spoilage data from a European dairy using the bioprotective culture. When the model prediction, based on a mixture of the 4 specific yeast strains, was compared with spoilage data from the European dairy, the observed effect of bioprotective cultures was considerably higher than predicted, potentially influenced by the presence of contaminating strains more sensitive to a bioprotective culture than those characterized here. The developed Monte Carlo models can predict yeast spoilage levels in yogurt at specific production settings and how this may be affected by various parameters and addition of bioprotective cultures.


Assuntos
Saccharomyces cerevisiae , Iogurte , Animais , Microbiologia de Alimentos , Kluyveromyces , Filogenia
20.
J Food Sci ; 86(6): 2626-2639, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34077557

RESUMO

Skyr yogurts have been gaining prominence because of their different sensory characteristics. Due to their healthy appeal, the use of natural sweeteners to replace sucrose in this type of yogurt can be an alternative for incorporating a sweet taste, in addition to increasing the functionality of the product through the incorporation of prebiotics. This study aimed to determine whether the addition of fructooligosaccharide (FOS), sucrose, stevia, and thaumatin affects the sensory profile of the skyr yogurt with mango pulp and its acceptance in two Brazilian regions. Eight formulations of skyr with mango pulp were developed. The compositional parameters evaluated were moisture, protein, lipids, ash, and carbohydrate. The tests performed were ideal sweetness and mango flavor, sweetness equivalence for each sweetener used, Quantitative Descriptive Analysis (QDA), and consumer testing in the Southeast and Northeast regions of Brazil. In general, the addition of FOS did not impact the characteristics of the formulated skyr yogurt. The type of sweetener had an impact on the sensory profile and acceptance of the skyr yogurt, affected characteristics such as mango flavor, sweet taste, sweet aftertaste, bitter taste, bitter aftertaste, and metallic flavor. The results of the affective test demonstrated that, for consumers in the Southeast, mango flavor is a positive attribute in this yogurt, and for Northeastern consumers, in addition to mango flavor, sweetness must also be taken into consideration. PRACTICAL APPLICATION: This study may be useful for the dairy industry because in the literature, there is still a lack of sensory studies of skyr yogurt, especially when sucrose substitutes are used. The results of the consumer test in this work reinforce the importance of studies related to consumer preferences with cultural differences.


Assuntos
Aromatizantes/administração & dosagem , Mangifera/química , Prebióticos/administração & dosagem , Stevia/química , Edulcorantes/análise , Paladar/fisiologia , Iogurte/análise , Adolescente , Adulto , Brasil , Comportamento do Consumidor/estatística & dados numéricos , Humanos , Pessoa de Meia-Idade , Sacarose/química , Paladar/efeitos dos fármacos , Adulto Jovem
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