Strategies to Improve the Quality of Goat Yogurt: Whey Protein Supplementation and Milk Pre-Treatment with High Shear Dispersion Assisted by Ultrasound.

This work investigated the fermentation kinetics and characteristics of goat yogurt supplemented with bovine whey protein isolate (WPI) (0%, 2.5% and 5.0%) subjected to high shear dispersion (HSD) assisted by ultrasound (US). Protein supplementation and the physical processes increased the electronegativity of the zeta potential (≤60%), whereas particle size reduction was observed only with physical processes (≤42%). The addition of 2.5% WPI reduced yogurt fermentation time by 30 min. After 24 h of storage at 7 °C, lactic acid bacteria counts did not differ between samples (≥8 log CFU/mL), and the supplementation was sufficient to increase the apparent viscosity (≤5.65 times) and water-holding capacity (WHC) of the yogurt (≤35% increase). However, supplementation combined with physical processes promoted greater improvements in these parameters (6.41 times in apparent viscosity and 48% in WHC) (p < 0.05), as confirmed by the denser and better-organized protein clusters observed in microscopic evaluation. Thus, both approaches proved to be promising alternatives to improve goat yogurt quality. Therefore, the decision to adopt these strategies, either independently or in combination, should consider cost implications, the product quality, and market demand.

Impact of ultrasound and protease addition on the fermentation profile and final characteristics of fermented goat and sheep cheese whey.

Goat (GCW) and sheep cheese whey (SCW) are cheese by-products that can be fermented to develop a new product. However, the limited nutrient availability for lactic acid bacteria (LAB) growth and the low stability of whey are challenges. This work evaluated the addition of protease and/or ultrasound-assisted fermentation as tools to improve GCW and SCW fermentation and the final quality of the products. Results showed that the US/protease increased by 23-32% pH decline rate (for SCW only) and modified the separation of cream (≤ 60% for GCW) and whey (≤ 80% for both whey sources, with higher values for GCW) during storage, explained by changes in the microstructure protein, fat globules, and their interactions. Furthermore, the whey source/composition (mainly lower fat content in SCW) affected the destabilization rate and the LAB viability loss (1.5-3.0 log CFU/mL), caused by nutrient depletion and low tolerance at pH ~ 4.0. Finally, exploratory results showed that fermentation under sonication (with/without protease) resulted in 24-218% higher antioxidant activity in vitro than unfermented samples. Therefore, fermentation associated with proteases/sonication can be an interesting strategy to modify GWC and SCW, and the final process chosen depends on the desired changes in whey. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05767-3.

Proposta de Pesquisa Científica para Avaliação da Segurança Microbiológica de Queijos Artesanais fabricados com leite cru e maturados por período inferior a 60 dias produzidos no estado de São Paulo / Scientific Research Proposal for the Microbiological Safety Evaluation of Raw Milk Artisanal Cheeses Ripened for Less than 60 Days in the State of São Paulo

Introdução: No Brasil, a legislação exige maturação mínima de 60 dias para queijos produzidos com leite cru, salvo se houver comprovação científica de que a redução do prazo não compromete a segurança do produto, como ocorreu com alguns queijos artesanais tradicionais de diferentes regiões do estado de Minas Gerais. No estado de São Paulo, onde os produtores seguem formulações e processos específicos individuais, a falta de um padrão de pesquisa validado dificulta a avaliação da segurança microbiológica deste tipo de queijo, pois essas pesquisas são dispendiosas e não há garantia de que os parâmetros estabelecidos pelos pesquisadores seriam aceitos pelos serviços de inspeção. Objetivo: Para abordar este desafio, esta proposta visa estabelecer um modelo de pesquisa científica padronizado para avaliar a segurança de queijos de leite cru maturados por menos de 60 dias. Métodos: Com base na proposta do DIPOA para classificação de Risco de Estabelecimentos, foi criado um checklist para classificação dos estabelecimentos/produtos, considerando risco do produto, volume processado e características de desempenho do estabelecimento em relação às Boas Práticas de Fabricação.  Resultados: A pontuação obtida pela aplicação do checklist na produção do queijo em questão determina o risco do produto como baixo, médio, alto ou muito alto e auxilia no estabelecimento do número mínimo de amostras a serem avaliadas mensalmente. Discussão: Espera-se que essa pesquisa auxilie produtores e órgãos de registro, fiscalização e inspeção no processo de legalização dos queijos artesanais de leite cru, possibilitando o desenvolvimento rural e a fixação de mão de obra no campo. (AU)

Introduction: In Brazil, the legislation requires a minimum ripening period of 60 days for raw milk cheeses, unless scientific evidence shows that the reduction in the ripening time does not compromise food safety, as seen with traditional artisanal cheeses from the state of Minas Gerais. In the state of Sao Paulo, where many producers have developed their own specific formulations and processes, the lack of a standardized validated research protocol for these types of cheese hinders their microbiological safety evaluation, since this type of research is costly and there are no guarantees that the parameters stablished by the researchers would be accepted by the inspection services. Objectives: To address this challenge, this proposal aims to stablish a standardized scientific research protocol for assessing the safety of raw milk cheeses ripened for less than 60 days. Methods: Based on the DIPOA (Department of Inspection of Products of Animal Origin) risk classification model for establishments, a checklist was created to categorize establishments/products, taking into consideration the product's risk, processed volume, and the establishment's performance assessed on the basis of good manufacturing practices. Results: The score obtained through the checklist application determines the final risk level of the product, categorized as low, medium, high, or very high, and helps determining the minimum number of samples to be evaluated monthly. Discussion: This research protocol may help producers, regulatory, inspection, and registration bodies in the legalization process of raw milk artisanal cheeses, enabling rural development and fixation of workforce in rural settings. (AU)

Use of physical processes to maximize goat milk cream hydrolysis: Impact on structure and enzymatic hydrolysis.

This study evaluated the use of ultrasound (US), high-shear dispersion (HSD), stirring (ST), and low or high pressure homogenization (LPH or HPH) technologies to modify the goat milk cream (GMC) structure, focusing on improving the enzymatic hydrolysis of its lipids. The GMC structure was evaluated, as well as its creaming and emulsion stability index (ESI). The processed GMC was hydrolyzed by lipase at 50 °C for 300 min, and the fatty acids concentration (FAC) was evaluated over the reaction. ST, HPH, and HSD showed âˆ¼ 90% lower emulsion destabilization, 10 times higher ESI, and smaller fat globule size than unprocessed GMC. The pretreatments increased the hydrolysis rate up to 2.4 times and the final FAC up to 8.7 times. ST (4 min), HPH (40 MPa) and HSD (5 min/ 25,000 rpm) showed the best results, which were correlated with the changes in the GMC structure. The results suggest that the physical treatments impacted the substrate structure, favoring enzyme activity and accelerating the hydrolysis degree. Therefore, the application of physical processes can be an interesting strategy to enhance the hydrolysis of GMC, aiming to produce compounds of industrial interest.

Ultrasound-assisted enzymatic hydrolysis of goat milk casein: Effects on hydrolysis kinetics and on the solubility and antioxidant activity of hydrolysates.

This study evaluated the ability of ultrasound (US) bath to improve the hydrolysis of goat milk casein (GMC) by three commercial proteases (Alcalase, Brauzyn and Flavourzyme) using assisted reactions at 60 °C for up to 300 min. Process performance was evaluated based on the rate reaction, final hydrolysis degree, solubility, and antioxidant activity of the hydrolysates. For all enzymes, the US-assisted reaction increased the rate of GMC hydrolysis (up to 120%), the hydrolysis degree (23-48%), and the small peptides formed, i.e., those soluble in trichloroacetic acid (TCA) (up to 40%). Consequently, US-assisted GMC hydrolysis improved the solubility of the hydrolyzed product (up to a 35.7% increase after 300 min of reaction) and, compared to conventional hydrolysis, reduced the time to achieve the maximum solubility by up to 10 times. Regarding the in vitro antioxidant activity, especially for Alcalase, the technology promoted a higher scavenging capacity of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (p < 0.05), thus 10-fold accelerating the production of antioxidant peptides, according to ABTS assays (p < 0.05). In conclusion, the US-assisted enzymatic reaction is a promising technology to improve the hydrolysis rate and yield of the process of obtaining hydrolysates from GMC. Moreover, these hydrolysates showed high solubility and good in vitro antioxidant activity, which demonstrates the potential to be used as food ingredient with nutritional and techno-functional appeal.

Factors associated with diet changes during the COVID-19 pandemic period in Brazilian adults: Time, skills, habits, feelings and beliefs.

This study aimed to identify individual, household and sociodemographic factors associated with changes in food consumption that lead to changes in the diet quality, in the context of the COVID-19 pandemic concerning Brazilian adults. Improvements or worsening in diet quality (IDQ or WDQ) were verified using an exploratory online survey which investigated whether participants (n = 4780) increased or decreased their consumption of food subgroups that mark positive or negative food patterns. Respondents also agreed or disagreed with their beliefs about food safety, cooking skills, family support, home characterization, feelings and behaviors. All factors of influence on the IDQ or WDQ groups were always compared against the general participants (who did not change their diet sufficiently to be classified into these groups). Individuals from the IDQ group spent more time on food (81.4% versus 62.0%), started to cook more often (91.4%), were more confident with their cooking skills (p < 0.01) and positive feelings were at least 2.5 times more prevalent. Adjusted analysis showed the chance to improve diet was 1.39 higher among those who did not feel overworked and increased 1.07 in each additional cooking chore shared between household members. For each additional positive feeling, the odds were 1.41 to IDQ and 0.67 to WDQ. Moreover, for each additional negative feeling the chances for WDQ were 1.21 and 0.90 for IDQ. Those in the WDQ group were more unaware of issues related to contagion during meals, they were not afraid of eating food prepared outside their home and agreed that industrialized food is safer (OR = 1.85). These results highlight the associated factors in improving or worsening diet patterns as a consequence of the COVID-19 pandemic, supporting messages presented in Dietary Guidelines.

Application of high-pressure homogenization on gums.

High-pressure homogenization (HPH) is an emerging process during which a fluid product is pumped by pressure intensifiers, forcing it to flow through a narrow gap, usually measured in the order of micrometers. Gums are polysaccharides from vegetal, animal or microbial origin and are widely employed in food and chemical industries as thickeners, stabilizers, gelling agents and emulsifiers. The choice of a specific gum depends on its application and purpose because each form of gum has particular values with respect to viscosity, intrinsic viscosity, stability, and emulsifying and gelling properties, with these parameters being determined by its structure. HPH is able to alter those properties positively by inducing changes in the original polymer, allowing for new applications and improvements with respect to the technical properties of gums. This review highlights the most important advances when this process is applied to change polysaccharides from distinct sources and molecular structures, as well as the future challenges that remain. © 2017 Society of Chemical Industry.

Biophysical evaluation of milk-clotting enzymes processed by high pressure.

High pressure processing (HPP) is able to promote changes in enzymes structure. This study evaluated the effect of HP on the structural changes in milk-clotting enzymes processed under activation conditions for recombinant camel chymosin (212MPa/5min/10°C), calf rennet (280MPa/20min/25°C), bovine rennet (222MPa/5min/23°C), and porcine pepsin (50MPa/5min/20°C) and under inactivation conditions for all enzymes (600MPa/10min/25°C) including the protease from Rhizomucor miehei. In general, it was found that the HPP at activation conditions was able to increase the intrinsic fluorescence of samples with high pepsin concentration (porcine pepsin and bovine rennet), increase significantly the surface hydrophobicity and induce changes in secondary structure of all enzymes. Under inactivation conditions, increases in surface hydrophobicity and a reduction of intrinsic fluorescence were observed, suggesting a higher exposure of hydrophobic sites followed by water quenching of Trp residues. Moreover, changes in secondary structure were observed (with minor changes seen in Rhizomucor miehei protease). In conclusion, HPP was able to unfold milk-clotting enzymes even under activation conditions, and the porcine pepsin and bovine rennet were more sensitive to HPP.

Vida de prateleira de alface americana tratada com água ozonizada / Shelf life evaluation of the iceberg lettuce sanitized with ozone water

RESUMO:Este trabalho avaliou se a higienização de alface americana com água ozonizada, na concentração de 1,0mg L-1 por 1, 2 ou 3 minutos, seria capaz de aumentar a vida útil do produto quando armazenado a 2ºC. Foram avaliadas as populações de microrganismos aeróbios mesófilos, Enterobacteriaceae, bolores e leveduras, coliformes totais, coliformes termotolerantes e pesquisa de Salmonellasp ao longo do tempo. Imediatamente após o processamento por 3 minutos, foram obtidas reduções decimais de 4,07; 3,36; 3,20; 2,18 e 2,18 de microrganismos aeróbios mesófilos,Enterobacteriaceae, bolores e leveduras, coliformes totais, coliformes termotolerantes, respectivamente. A presença de Salmonellasp. não foi observada em nenhuma das condições estudadas. Além do efeito na inativação inicial, o processamento com ozônio melhorou a estabilidade da alface durante a estocagem, aumentando o tempo para o início do crescimento microbiano (de zero para quatro dias) e reduzindo a taxa de crescimento dos microrganismos, especialmente quando a sanitização foi realizada por 3 minutos de contato. Os resultados demonstraram que a alface tratada com água ozonizada atendeu aos parâmetros da legislação durante o período avaliado, reduzindo a contaminação inicial das alfaces (que, sem tratamento, estavam microbiologicamente impróprias para consumo pela contagem de coliformes) e mantendo essas contaminações em níveis aceitáveis por até 10 dias, sob refrigeração.

ABSTRACT:This research studied the impact of Iceberg lettuce sanitation using ozonized water at 1.0mg L-1 for 1, 2 and 3 minutes in the vegetable shelf-life at 2ºC. It was evaluated populations of aerobic mesophilic bacteria, EnterobacterIaceae, molds/yeasts, total and thermtolerants coliforms, andSalmonellasp. Immediately after 3 minutes of sanitation, decimal reductions of 4.07 (aerobic mesophilic bacteria), 3.36 (EnterobacterIacea), 3.2 (molds/yeasts), 2.18 (total coliforms) and 2.18 (thermtolerants coliforms) were reached. Salmonellasp. was not founded at any evaluated condition. Additionally to the initial reduction, the ozonization improved the lettuce stability during its shelf-life, increasing the delay for microbial growth (from zero to four days) and reducing the microbial growth rate. It occurred especially when sanitation with ozone was carried for 3 minutes of contact. The results showed that the Iceberg lettuce sanitized with ozonated water meets the Brazilian law during the evaluated period, reducing lettuce initial load (that was initially unsafe due to high count of coliforms) and keeping this contamination acceptable for 10 days under refrigeration.

High Pressure Homogenization of Porcine Pepsin Protease: Effects on Enzyme Activity, Stability, Milk Coagulation Profile and Gel Development.

This study investigated the effect of high pressure homogenization (HPH) (up to 190 MPa) on porcine pepsin (proteolytic and milk-clotting activities), and the consequences of using the processed enzyme in milk coagulation and gel formation (rheological profile, proteolysis, syneresis, and microstructure). Although the proteolytic activity (PA) was not altered immediately after the HPH process, it reduced during enzyme storage, with a 5% decrease after 60 days of storage for samples obtained with the enzyme processed at 50, 100 and 150 MPa. HPH increased the milk-clotting activity (MCA) of the enzyme processed at 150 MPa, being 15% higher than the MCA of non-processed samples after 60 days of storage. The enzyme processed at 150 MPa produced faster aggregation and a more consistent milk gel (G' value 92% higher after 90 minutes) when compared with the non-processed enzyme. In addition, the gels produced with the enzyme processed at 150 MPa showed greater syneresis after 40 minutes of coagulation (forming a more compact protein network) and lower porosity (evidenced by confocal microscopy). These effects on the milk gel can be associated with the increment in MCA and reduction in PA caused by the effects of HPH on pepsin during storage. According to the results, HPH stands out as a process capable of changing the proteolytic characteristics of porcine pepsin, with improvements on the milk coagulation step and gel characteristics. Therefore, the porcine pepsin submitted to HPH process can be a suitable alternative for the production of cheese.

Effects of high pressure homogenization on the activity, stability, kinetics and three-dimensional conformation of a glucose oxidase produced by Aspergillus niger.

High pressure homogenization (HPH) is a non-thermal method, which has been employed to change the activity and stability of biotechnologically relevant enzymes. This work investigated how HPH affects the structural and functional characteristics of a glucose oxidase (GO) from Aspergillus niger. The enzyme was homogenized at 75 and 150 MPa and the effects were evaluated with respect to the enzyme activity, stability, kinetic parameters and molecular structure. The enzyme showed a pH-dependent response to the HPH treatment, with reduction or maintenance of activity at pH 4.5-6.0 and a remarkable activity increase (30-300%) at pH 6.5 in all tested temperatures (15, 50 and 75°C). The enzyme thermal tolerance was reduced due to HPH treatment and the storage for 24 h at high temperatures (50 and 75°C) also caused a reduction of activity. Interestingly, at lower temperatures (15°C) the activity levels were slightly higher than that observed for native enzyme or at least maintained. These effects of HPH treatment on function and stability of GO were further investigated by spectroscopic methods. Both fluorescence and circular dichroism revealed conformational changes in the molecular structure of the enzyme that might be associated with the distinct functional and stability behavior of GO.

Quality of mango nectar processed by high-pressure homogenization with optimized heat treatment.

UNLABELLED: This work aimed to evaluate the effect of high-pressure homogenization (HPH) with heat shock on Aspergillus niger, vitamin C, and color of mango nectar. The nectar was processed at 200 MPa followed by heat shock, which was optimized by response surface methodology by using mango nectar ratio (45 to 70), heat time (10 to 20), and temperature (60 to 85 °C) as variables. The color of mango nectar and vitamin C retention were evaluated at the optimized treatments, that is, 200 MPa + 61.5 °C/20 min or 73.5 °C/10 min. The mathematical model indicates that heat shock time and temperature showed a positive effect in the mould inactivation, whereas increasing ratio resulted in a protective effect on A. niger. The optimized treatments did not increase the retention of vitamin C, but had positive effect for the nectar color, in particular for samples treated at 200 MPa + 61.5 °C/20 min. PRACTICAL APPLICATION: The results obtained in this study show that the conidia can be inactivated by applying HPH with heat shock, particularly to apply HPH as an option to pasteurize fruit nectar for industries.

Review: Microbiological quality and safety of fruit juices--past, present and future perspectives.

In this review paper, several aspects of fruit juice microbiology, from past to future perspectives, are considered. An overview of the most relevant outbreaks involving foodborne pathogens and spoilage microorganisms associated with fruit juices is provided. One of the sections provides data on the sources of fruit juice contamination, followed by perspectives on preservation methods. Furthermore, considerations on the role of international guidelines about exotic fruit juices in respect to public health, and of the microbiological status of fruit juices used as food/beverage ingredients are discussed. Issues and challenges highlight how the microbiology of fruit juices has evolved over the years, when aspects of stability or microbiological safety are under consideration.