Engineering the β-galactosidase from Aspergillus oryzae for making lactose-free and no-sugar-added yogurt

Yogurt usually contains 5-7% sugar and 3-5% lactose. As β-galactosidases can hydrolyze lactose and improve sweetness, they have the potential to produce lactose-free (LF) and no-sugar-added (NSA) yogurt. In this study, β-galactosidase AoBgal35A from Aspergillus oryzae was engineered by site-saturation mutagenesis. Results of 19 variants of T955 residue showed that lactose hydrolysis rate of T955R-AoBgal35A was up to 90.7%, much higher than 78.5% of the wild type. Moreover, the optimal pH of T955R-AoBgal35A was shifted from pH 4.5 to pH 5.5 and the optimal temperature decreased from 60°C to 50°C. The mutant T955R-AoBgal35A was successfully expressed in Komagatella pastoris, which produced extracellularly 4528 U/mL of β-galactosidase activity. The mutant T955R-AoBgal35A was used to produce LF yogurt. Streptococcus thermophilus counts of LF yogurt increased from 7.9 to 9.5 lg cfu/g, significantly higher than that of the control group (8.9 lg cfu/g). Residual lactose content of LF yogurt was 0.13%, meeting the requirement of "lactose-free" label (<0.5%, GB 28050-2011, China). Furthermore, sugar in yogurt was replaced by whey powder to produce LF-NSA yogurt. The optimal addition content of whey powder was 7.5%. The texture, WHC and titratable acidity of LF and LF-NSA yogurt achieved good stability during the shelf life. Therefore, this study provides an insight for technological implications of β-galactosidases in the dairy industry.

Low Fat Yoghurts Produced with Different Protein Levels and Alternative Natural Sweeteners

The food industry is looking for substitutes for sucrose in food items due to the excessive consumption of products with added sugar and the demand for healthier products. Alternative natural sweeteners can help achieve this goal. Different types of low-fat yoghurts (1% fat), with low-protein and high-protein levels (3% and 4.5-6.5% protein, respectively), were produced using alternative natural sweeteners. The low-protein yoghurts were made with stevia (0.03% w/w) or agave syrup (4.5% w/w). The high-protein yoghurts were made with stevia (0.04% w/w), xylitol (6% w/w) or honey (6% w/w). Sucrose (6% w/w) was used as a control in both trials. pH and titratable acidity, CIEL*a*b* color parameters, syneresis index, rheology and the texture profile of the low-fat yoghurts were evaluated over refrigerated storage. All products underwent sensory evaluation by an untrained panel. The high-protein yoghurts were found to be more acidic (>1% as lactic acid), had a lower syneresis index (between 2.1 and 16.2%) and a better consistency (stronger gel structure) than the low-protein yoghurts. In terms of rheological parameters, stevia-sweetened yoghurts scored higher than the other sweetened yoghurts, showing a better gel structure. The different sweeteners tested did not significantly affect the sensory properties of the yoghurts, although the high-protein yoghurts scored higher for most of the attributes evaluated. Overall, consumers preferred stevia-sweetened yoghurts to yoghurts sweetened with sucrose or agave for the low-protein yoghurts. Of the tested formulations, those containing high protein with the alternative natural sweetener xylitol received higher scores in all attributes. These results reveal the potential of the tested natural sweeteners as sucrose substitutes, while contributing to improving the nutritional value of yoghurts.

Investigation of rheological, physicochemical, and sensorial properties of traditional low-fat Doogh formulated

Doogh is a fermented beverage made from yoghurt with water and salt. Similarly, drinks based on yoghurt are available in different countries with varying degrees of dilution, fat content, rheological properties, and taste. In this project, the use of mathematical calculations in describing rheological parameters from traditional low-fat Doogh enriched with Caspian Sea (Huso huso) gelatin (0.4 w/v %), xanthan hydrocolloids (0.4 w/v %), and their mixture at a ratio of 0.2:0.2 w/v % studied. Also, serum isolation, pH, and sensory evaluation of samples were investigated. Also, the relationship between apparent viscosity and temperature of Doogh samples using the Arrhenius equation was studied. The sensory evaluation revealed that the overall acceptance scores of the samples containing gelatin, xanthan, mix, and control were 4.31, 4.33, 4.58, and 4.12, respectively. The study on serum separation value showed control sample (45.07) and mix sample (0.84) at the end of 30 days. On the first day, the pH of the Doogh samples decreased with the addition of hydrocolloids, and this trend was time dependent. pH reduction was higher in Doogh with gelatin than in other samples. Mathematical calculations showed that the low-fat Doogh is a non-Newtonian type and shear-thinning (Pseudoplastic) fluid. The activation energy was calculated between 11.65 and 19.15 kJ/mol. According to the obtained results, it concluded that the use of two hydrocolloid compounds improved the physicochemical and sensory characteristics of the low-fat Doogh samples. Also, the Ostwald-de Waele mathematical model had a high correlation with the rheological behavior of the samples.

Parental perception of children's school lunch milk

School lunch programs are mandated by the US Code of Federal Regulations to serve pasteurized milk that is skim or 1% fat and fortified with vitamins A and D. In recent years, proposals have been made to alter nutritional requirements for school lunches and school lunch milk, including changes to the milk fat and flavor options available. The objective of this study was to evaluate parental understanding and perception of school lunch milk to better understand how changes to school lunch milk are perceived by parents. Four focus groups (n = 34) were conducted with parents of school-aged children (5-13 yr) who purchased milk as part of a lunch at school. Participants were asked about school lunch milk, including nutritional content, packaging, and flavoring. Focus groups included a build-your-own milk activity and discussion of children's milk products currently available on the market. Two subsequent online surveys were conducted with parents of school-aged children (survey 1, n = 216; survey 2, n = 133). Maximum difference scaling was used to evaluate what beverages parents would prefer their child to drink at school (survey 1) and which attributes of chocolate milk for children were most important to parents (survey 2). An adaptive choice-based conjoint activity (survey 1) included flavor, milk fat, heat treatment, label claims, and packaging type. Both surveys included questions to evaluate knowledge of milk nutrition and attitudes regarding milk and flavored milk. Agree/disagree questions were used in both surveys to assess parental opinions of school lunch milk. Survey 2 also included semantic differential (sliding scale) questions to assess parental opinions of chocolate milk and their acceptance of sugar alternatives in chocolate milk served in schools. Parents were familiar with the flavor options and packaging of school lunch milk, but expressed limited familiarity with school lunch milk fat content. Parents perceived milk to be healthy and a good source of vitamin D and calcium. From survey results, parents placed the highest importance on school lunch milk packaging, followed by milk fat percentage and flavoring over label claims and heat treatment. The ideal school lunch milk for parents was unflavored (white milk) or chocolate, 2% fat, and packaged in a cardboard gabletop carton. For school lunch chocolate milk, 3 distinct clusters of parents with differing opinions for children's chocolate milk were identified. Parents are largely unfamiliar with the specific attributes and nutritional profile of milk served in schools but believe that schools should offer milk to their children as part of breakfast and lunch. Parents in both surveys also displayed a preference for 2% fat milk over low-fat options, which provides actionable insight for both governmental bodies determining educational and nutritional policies for school meals and fluid milk producers seeking to optimize their products intended for schools.

Probiotication in multigrain dough and biscuits with the incorporation of erythritol: Evaluation of techno-functional properties using chemometric approach

This study aims to develop a multigrain probiotic biscuit and evaluate the effect of erythritol as a sugar replacer on the rheological properties of dough, along with the physicochemical and organoleptic properties of biscuits. The higher viscoelasticity of dough was observed at a 25% sugar replacement level with erythritol, and the calorific value of biscuits was significantly (p < 0.05) reduced from 415.12 to 404.69 Cal/100 g with increasing in the sugar replacement from 0% to 75%. The biscuits with higher concentrations of erythritol showed reduced water activity (aw) and higher hardness values. From Pearson's correlation analysis, it was observed that the probiotic viability had a positive relation with moisture, fat, energy, aw, and diameter and a negative association with the protein and fiber content of biscuits. The 25% replacement of sugar with erythritol showed a higher probiotic count (> 7 log CFU/g) and improved physicochemical and sensory properties during the storage period, which was further confirmed by the principal component analysis. So, it was recommended that the partial replacement of sugar with erythritol up to 25% is desirable for developing low-calorie bakery products without any alteration in the functional groups and improving the internal structure of the biscuits.

Advances in Low-Lactose/Lactose-Free Dairy Products and Their Production

With increasing health awareness worldwide, lactose intolerance has become a major concern of consumers, creating new market opportunities for low-lactose/lactose-free dairy foods. In recent years, through innovating processes and technologies, dairy manufacturers have significantly improved the variety, and functional and sensory qualities of low-lactose and lactose-free dairy products. Based on this, this paper first covers the pathology and epidemiology of lactose intolerance and market trends. Then, we focus on current advantages and disadvantages of different lactose hydrolysis technologies and improvements in these technologies to enhance nutritional value, and functional, sensory, and quality properties of lactose-free dairy products. We found that more and more cutting-edge technologies are being applied to the production of lactose-free dairy products, and that these technologies greatly improve the quality and production efficiency of lactose-free dairy products. Hopefully, our review can provide a theoretical basis for the marketing expansion and consumption guidance for low-lactose/lactose-free dairy products.

Cross-sectional determinants of lactose-free food awareness and purchase among adult consumers

This research was conducted to evaluate the knowledge and purchasing behaviour of consumers regarding lactose-free foods. Study data were collected from 1882 individuals with the help of a questionnaire form. Attitudes towards animal welfare, healthy nutrition and gastrointestinal symptoms were also evaluated. The majority (86.6%) of the participants reported that they had heard of the concept of lactose-free foods before, but more than half (67.0%) did not report buying them because of their higher costs compared to regular products and lack of sufficient information. Not causing gas/bloating (32.5%) and being healthier (28.3%) were shown to be the most significant motivational factors in purchasing lactose-free foods (P < 0.05). The factors affecting purchase of lactose-free products were education, employment status, history of having a food intolerance test and animal welfare perception together with higher scores from the gastrointestinal symptom rating scale, and attitude scale for healthy nutrition (P < 0.05). Body mass index was not found to be an effective factor determining purchase intention. The results provide a general overview of consumers, however, further studies on other demographic groups are needed.

Recent advance in technological innovations of sugar-reduced products

Sugar is crucial as an essential nutrient for humans as well as for providing texture, sweetness and so on to food. But with the rise in people's pursuit of health, it is becoming increasingly clear that excessive consumption of sugar can locate a load on the body. It has been that excessive sugar is associated with many diseases, such as dental caries, obesity, diabetes, and coronary heart disease. Therefore, researchers and industries are trying to reduce or substitute sugar in food without affecting the sensory evaluation. Substituting sugar with sweeteners is alternatively becoming the most traditional way to minimize its use. So far, the sweeteners such as stevia and xylitol have been are commercially applied. Several studies have shown that technological innovation can partially compensate for the loss in sweetness as a result of sugar reduction, such as cross-modal interactions that stimulate sweetness with aroma, nanofiltration that filters disaccharides and above, enzyme-catalyzed sugar hydrolysis, and microbial fermentation that turns sugar into sugar alcohol. This review summarizes these studies to enhance the safety and quality of sugar-reduced products, and will provide some theoretical frameworks for the food industry to reduce sugar in foods, meet consumers' needs, and promote human health.

Replacement of refined sugar by natural sweeteners: focus on potential health benefits

Refined sugar is a processed product containing 99% sucrose, which is obtained from sugarcane (70%) or sugar beet (30%). In modern societies, sugar continues to play a significant role in the diet, recognised not only for its flavour and special sweetening properties but also for its role in food preservation. On the other hand, a high consumption of refined sugar is associated with non-communicable diseases and many health issues such as a high risk of dental caries, overweight and neurodevelopmental disorders in children. Alternatives like unrefined sugars have generated a lot of interest as a healthy substitute due to their nutraceutical properties. This paper is aimed to review the beneficial effects of sugar derived from natural sources and highlight health problems that could be caused by refined processed sugar. Refined sugar is frequently used in variety of items including processed foods, soft drinks or ice creams although it is considered unhealthy due to its high salt and sugar content as well as added fats and artificial coloring. Natural sugars are preferred because they have a high nutritional value and a high concentration of healthy compounds, which offset the negative effects of refined sugar. Therefore, removing refined sugar or at least reducing its consumption should be promoted as a healthier option in food choices.

Impact of Stevia rebaudiana substitution on physico-chemical characteristics, sensory profile and microstructure in selected Indian desserts

Stevia rebaudiana has been used since hundreds of years as a natural sweetener, it is 300-450 times sweeter than sugar. The study aimed at incorporation of S. rebaudiana in traditional Indian desserts and test its sensory profile, storage properties, textural and color attributes. Carrot halwa (CH) and kesar peda (KP) were prepared with variations such as complete replacement of sugar in variation 1 (V1: CHV1 & KPV1) and 40% replacement of sugar in variation 2 (V2: CHV2 & KPV2) with stevia. Standard methods such as Quantitative Descriptive Analysis scores for sensory profile, fat oxidation for storage studies and surface morphology, texture profile and color analysis of samples were studied. Sensory profile revealed higher taste acceptability in CHV1 and KPV2. During storage, the maximum peroxide value was 5 mEq/kg in all products of refrigerated KP. Microstructural studies revealed changes in surface morphology wherein stevia incorporation increased ragged edges in CH and porosity in KP. Both products exhibited increased hardness, gumminess and chewiness during storage. There was no major change in the color profile of products. Overall, incorporation of stevia in Indian desserts can significantly reduce the use of sugar and can be relished by people who are health conscious.

Sugar reduction methods and their application in confections: a review

Many American adults consume almost double the daily recommended amount of sugar. With excess consumption of sugar and consequential health problems arising, food manufacturers are investigating methods to reduce sugar while maintaining similar functional and sensory properties. The body of literature was searched for papers regarding sugar reduction, and the main methods of sugar reduction are summarized herein with a specific focus on high sugar products. Reducing sugar in confections is possible; however, the challenge is maintaining the balance between texture and sweetness perception. Texture plays a large role in the sweetness perception of confections, with firmer products often being perceived as less sweet. Depending on the method, 20-40% of sugar can be removed from confections without sacrificing sensory acceptance, often replaced with multiple ingredients. Further investigation is needed on confection models and how the emerging health trends set the foundation for sugar reduction.

Multiscale Approach to Dairy Products Design

Dairy products are among the most popular nutritious foods in the world. Understanding the relationship between the composition, process, and structural properties at different scales (molecular, microscopic, and macroscopic) is fundamental to designing dairy products. This review highlights the need to analyze this relationship from different scales as an essential step during product design through a multiscale approach.

Natural sweeteners: Sources, extraction and current uses in foods and food industries

Food producers have leaned towards alternative natural and synthetic sweeteners in food formulations to satisfy market demands. Even so, several synthetic sweeteners (e.g., aspartame, saccharin, sucralose) are becoming less popular due to health-related concerns, lower nutritional values, and controversies around their safety. Conversely, natural sweeteners confer favourable customer perceptions due to their association to a healthier lifestyle and higher nutritional values. This article discusses the evidence of natural sweeteners in the available commercial products. A comprehensive review of natural sweeteners is presented, which includes their resources, properties and extraction methods, as well as a discussion on several emerging technologies that offer improvements to the traditional extraction methods. Finally, the progress of natural sweeteners in the food industry is assessed, and the commercial food products containing these natural sweeteners are mentioned.

Children's perceptions of fluid milk with varying levels of milkfat

Schools participating in federal meal programs are limited to serving skim or low-fat (≤1%) flavored and unflavored milk. Few studies have directly addressed child perceptions and preferences for milk containing different amounts of milkfat. The objective of this study was to determine whether children can differentiate between flavored and unflavored fluid milk containing varying levels of milkfat and whether preferences for certain levels of milkfat exist. Flavored and unflavored milks containing 4 different percentages of milkfat (≤0.5, 1, 2, and 3.25%) were high-temperature, short-time processed, filled into half-gallon light-shielded milk jugs, and stored at 4°C in the dark. Milks were evaluated by children (ages 8-13 yr) following 7 d at 4°C. Acceptance testing and tetrad difference testing were conducted on flavored and unflavored milks with and without visual cues to determine if differences were driven by visual or flavor or mouthfeel cues. Child acceptance testing (n = 138 unflavored; n = 123 flavored) was conducted to evaluate liking and perception of selected attributes. Tetrad testing (n = 127 unflavored; n = 129 flavored) was conducted to determine if children could differentiate between different fat levels even in the absence of a difference in acceptance. The experiment was replicated twice. When visual cues were present, children had higher overall liking for 1% and 2% milks than skim for unflavored milk and higher liking for chocolate milks containing at least 1% milk fat than for skim. Differences in liking were driven by appearance, viscosity, and flavor. In the absence of visual cues, no differences were observed in liking or flavor or mouthfeel attributes for unflavored milk but higher liking for at least 1% milk fat in chocolate milk compared with skim was consistent with the presence of visual cues. From tetrad testing, children could visually tell a difference between all unflavored pairs except 2% versus whole milk and could not detect consistent differences between milkfat pairs in the absence of visual cues. For chocolate milk, children could tell a difference between all milk fat pairs with visual cues and could tell a difference between skim versus 2% and skim versus whole milk without visual cues. These results demonstrate that in the absence of package-related flavors, school-age children like unflavored skim milk as well as milk with higher fat content in the absence of visual cues. In contrast, appearance as well as flavor and mouthfeel attributes play a role in children's liking as well as their ability to discriminate between chocolate milks containing different amounts of fat, with chocolate milk containing at least 1% fat preferred. The sensory quality of school lunch milk is vital to child preference, and processing efforts are needed to maximize school milk sensory quality.

Advantages and disadvantages of non-starter lactic acid bacteria from traditional fermented foods: Potential use as starters or probiotics

Traditional fermented foods are a significant source of starter and/or non-starter lactic acid bacteria (nsLAB). Moreover, these microorganisms are also known for their role as probiotics. The potential of nsLAB is huge; however, there are still challenges to be overcome with respect to characterization and application. In the present review, the most important steps that autochthonous lactic acid bacteria isolated from fermented foods need to overcome, to qualify as novel starter cultures, or as probiotics, in food technology and biotechnology, are considered. These different characterization steps include precise identification, detection of health-promoting properties, and safety evaluation. Each of these features is strain specific and needs to be accurately determined. This review highlights the advantages and disadvantages of nsLAB, isolated from traditional fermented foods, discussing safety aspects and sensory impact.

Quality, physicochemical, and textural properties of dairy products containing fruits and vegetables: A review

Due to the high utilization rate of dairy products, enrichment of these products will successfully decrease or prevent diseases related with nutrition deficiencies. Fruits and vegetables in different forms (i.e., fresh, juices, powder, puree, and extract) are excellent sources for the enrichment of dairy products because of their desired taste, color, aroma, fibers, and vitamins content. So, this manuscript reviews the effect of some fruits and vegetables on the rheological behavior, physicochemical attributes, color parameters, sensorial and quality properties of dairy products including cheeses, ice creams, and yogurts. The physicochemical, color, texture, and sensorial properties of dairy products were affected with addition of fruits or vegetables. Also, the addition of these products contributes to the higher content of vitamins, natural colorants, minerals, polyphenols, crude fiber, and carotenoids. In addition, some fruits and vegetables are considered as potential dairy products stabilizing agent due to their desirable functional properties, such as water binding and holding, gelling and thickening ability. In summary, enrichment of cheeses, ice creams, and yogurts with fruits and vegetables increase the market share of these products due to the high demand for goods for an improved diet, rich in compounds with antioxidant activity and biological properties.

Purified lactases versus whole-cell lactases-the winner takes it all

Lactose-free dairy products are in great demand worldwide due to the high prevalence of lactose intolerance. To make lactose-free dairy products, commercially available β-galactosidase enzymes, also termed lactases, are used to break down lactose to its constituent monosaccharides, glucose and galactose. In this mini-review, the characteristics of lactase enzymes, their origin, and ways of use are discussed in light of their potential for hydrolyzing lactose. We also discuss whole-cell lactase catalysts, which appear to have great potential in terms of cost reduction and convenience, and which are more natural alternatives to purified enzymes. Lactic acid bacteria (LAB) already used in food fermentations seem to be optimal candidates for whole-cell lactases. However, they have not been industrially exploited yet due to technical hurdles. For whole-cell lactases to be efficient, the lactase enzymes inside the cells must be made available for lactose hydrolysis, and thus, cells need to be permeabilized or disrupted prior to use. Here we review state-of-the-art approaches for disrupting or permeabilizing microorganisms. Lastly, based on recent scientific achievements, we propose a novel, resource-efficient, and low-cost scenario for achieving lactose hydrolysis at a dairy plant using a LAB whole-cell lactase.Key points• Lactases (β-galactosidase) are essential for producing lactose-free dairy products• Novel permeabilization techniques facilitate the use of LAB lactases• Whole-cell lactase catalysts have great potential for reducing costs and resources Graphical abstract.

Determination of Carbohydrates in Lactose-Free Dairy Products to Support Food Labelling

Milk and its derivatives are the basis of human nutrition since childhood. Given their importance within a balanced diet, the determination of carbohydrates in milk and its derivatives is fundamental for two reasons: one of alimentary origin related to intolerances and the other one of technological origin, especially for PDO (Protected Designation of Origin) products. The dietetic approach, including lactose-free products, has a crucial role in the management of lactose intolerance, but labelling and compositional rules indicating the absence or reduced presence of lactose in food are currently not harmonised at Union level. Considering the above-mentioned issues and the absence of official methods for the determination of low sugar concentrations, we propose a new and simple IC-HRMS method to detect carbohydrates in milk and different lactose-free derivatives, which can allow the definition of concentration limits useful to characterise products suitable for specific dietary regimes.

Lactose intolerance: An update on its pathogenesis, diagnosis, and treatment

Lactose intolerance has a high prevalence worldwide, ranging between 57% and 65%. It is caused by a reduction or loss of the activity of the intestinal enzyme lactase-phlorizin hydrolase, responsible for the digestion of lactose. This alteration determines an increased osmotic load in the small intestine and the fermentation of lactose by the bacterial flora, which leads to a high production of short-chain fatty acids and gas. This is followed by the onset of abdominal pain, diarrhea, and flatulence. In addition to these problems, it was found that subjects with lactose intolerance have an increased risk of developing various extra-intestinal diseases, including cancers. The diagnosis is essential to undertake an adequate treatment and, for this purpose, different methods have been tested. These include genetic test, hydrogen breath test (HBT), quick lactase test, and lactose tolerance test. HBT is the most used method because it is non-invasive, inexpensive, and highly sensitive and specific, as well as easy to perform. In clinical practice, the other methods are mainly used as HBT integration tests. There are also many therapeutic options. An appropriate intervention concerns the dietetic style, such as the consumption of lactose-free foods, but with nutritional characteristics comparable to dairy products. Other valid choices are represented by the use of exogenous enzymes, probiotics, prebiotics, the selection of milk containing specific types of beta-caseins. This review is intended to illustrate the diagnostic methods currently available and the possible therapeutic options for lactose intolerance.

Age and time trends of dairy intake among children and adolescents of the DONALD study

Purpose

To describe age and time trends in dietary intake of Total Dairy (TD) (g/1000 kcal Total Energy Intake) and types of dairy (weight percent of total dairy intake, w%TD) represented as Low Fat Dairy (LFD), High Sugar Dairy (HSD), Fermented Dairy (FD) and Liquid Dairy (LD) among children and adolescents in Germany.

Methods

Overall, 10,333 3-day dietary records kept between 1985 and 2019 by 1275 DONALD participants (3.5–18.5 years; boys: 50.8%) were analyzed using polynomial mixed-effects regression models.

Results

TD intake decreased with age (♂: linear trend p < 0.0001; ♀: linear and quadratic trend p < 0.0001), whereas FD (♀: linear, quadratic, cubic trend p ≤ 0.02) increased slightly in girls. HSD (♂: linear, quadratic, cubic trend p ≤ 0.004; ♀: linear, quadratic, cubic trend p ≤ 0.005) and LD (linear, quadratic trend p ≤ 0.0002) decreased with age. In terms of time trends, TD intake decreased in the last three decades, especially since 1995 (quadratic trend for ♂ 0.0007 and ♀ p = 0.004). LFD intake increased until 2010 and decreased thereafter (linear, quadratic, cubic trend p < 0.0001). HSD decreased until 1995, then increased until 2010 and decreased again afterwards (♂: linear, quadratic, cubic trend p ≤ 0.001; ♀: linear, quadratic, cubic trend p ≤ 0.003). While FD intake increased linear (in both ♂ and ♀: p < 0.0001), LD intake decreased (linear, quadratic trend p ≤ 0.03).

Conclusion

Our results showed changes in dairy consumption patterns among children and adolescents over the past three decades, demonstrating a decrease in TD intake with age and time, and a shift from liquid to solid dairy products with a simultaneous increase in fermented dairy products, while LFD and HSD fluctuated over time. Further evaluations will examine the health significance of these consumption patterns.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02555-7.

Encapsulated NOLA™ Fit 5500 Lactase—An Economically Beneficial Way to Obtain Lactose-Free Milk at Low Temperature

The current requirements of industrial biocatalysis are related to economically beneficial and environmentally friendly processes. Such a strategy engages low-temperature reactions. The presented approach is essential, especially in food processes, where temperature affects the quality and nutritional value foodstuffs. The subject of the study is the hydrolysis of lactose with the commercial lactase NOLA™ Fit 5500 (NOLA). The complete decomposition of lactose into two monosaccharides gives a sweeter product, recommended for lactose intolerant people and those controlling a product’s caloric content. The hydrolysis reaction was performed at 15 °C, which is related to milk transportation and storage temperature. The enzyme showed activity over the entire range of substrate concentrations (up to 55 g/L lactose). For reusability and easy isolation, the enzyme was encapsulated in a sodium alginate network. Its stability allows carrying out six cycles of the complete hydrolysis of lactose to monosaccharides, lasting from two to four hours. During the study, the kinetic description of native and encapsulated NOLA was conducted. As a result, the model of competitive galactose inhibition and glucose mixed influence (competitive inhibition and activation) was proposed. The capsule size does not influence the reaction rate; thus, the substrate diffusion into capsules can be omitted from the process description. The prepared 4 mm capsules are easy to separate between cycles, e.g., using sieves.

Lactose Intolerance and Its Dietary Management: An Update

Milk is the most common food consumed worldwide and is also a major ingredient in the preparation of various dairy products. However, despite the high production and consumption of milk and milk-based products, there is a large percent of the world's population that suffer from allergies to milk solids and lactose intolerance. Lactose intolerance specifically means the inability of the body to breakdown the sugar to its simplest form for assimilation and it is due to the inefficiency or lack of the enzyme in the human body. The most convenient prevention method for the affected population is to avoid milk and milk-based products but this may be a cause of development of other health related issues that result from inadequate nutrient consumption. To help find an alternative to this problem, this study aims at first studying the underlying information on lactose intolerance and then studying plant-based beverages as a possible alternative to milk and milk-based products. Key teaching pointsLactose intolerance specifically means the inability of the body to breakdown the sugar to its simplest form for assimilation and it is due to the inefficiency or lack of the enzyme in the human body.Consumption of probiotics may help relieve the symptoms of lactose intolerance.Soy beverage can be an economical alternative for lactose intolerant populations and has calcium content comparable to bovine milk.Calcium absorption in fortified plant based beverages depends upon type of calcium salt used.

Fructose and high fructose corn syrup: are they a two-edged sword?

High-fructose syrups are used as sugar substitutes due to their physical and functional properties. High fructose corn syrup (HFCS) is used in bakery products, dairy products, breakfast cereals and beverages, but it has been reported that there might be a direct relationship between high fructose intake and adverse health effects such as obesity and the metabolic syndrome. Thus, fructose has recently received much attention, most of which was negative. Although studies have indicated that there might be a correlation between high fructose-rich diet and several adverse effects, however, the results of these studies cannot be certainly generalised to the effects of HFCS; because they have investigated pure fructose at very high concentrations in measurement of metabolic upsets. This review critically considered the advantages and possible disadvantages of HFCS application and consumption in food industry, as a current challenging issue between nutritionists and food technologists.

Invited review: Maintaining and growing fluid milk consumption by children in school lunch programs in the United States

Fluid milk consumption among children has declined for decades. Adequate consumption of milk and dairy products, especially during childhood, has beneficial health outcomes for growth, development, and reduced risk of osteoporosis, hypertension, obesity, and cancer during adulthood. Satisfaction with milk flavor, perceived health benefits derived from milk, and habit are primary drivers of lifelong milk consumption. Child preferences and attitudes for milk may differ from those of adults, and as such, understanding and fulfilling the needs of children is crucial to reverse the decline in milk consumption. School meal programs make fluid milk accessible to millions of children each day; however, regulations and school lunch procurement systems in the United States sometimes make it difficult to provide novel or value-added milk products in these programs. Total consumption of all milk types in US schools declined by 14.2% from 2008 to 2017, and the percentage of children participating in the school lunch program has also declined. This decline has also been driven by declining average daily participation in the school meal program and may also reflect children's dissatisfaction with the sensory characteristics and the form of milk offered in schools. The change in form of milk offered in schools to lower fat and lower added sugar content in the United States has been driven by government-mandated school lunch calorie and fat requirements. This review describes the current milk consumption trends among children; the structure and basic requirements of the school lunch program in total and for milk; and the intrinsic, extrinsic, and environmental factors that influence child perception, preference, and consumption of fluid milk in the US school system.

Physicochemical and microbiological characteristics of camel milk yogurt as influenced by monk fruit sweetener

Camel milk, similar to cow milk, contains all of the essential nutrients as well as potentially health-beneficial compounds with anticarcinogenic, antihypertensive, and antioxidant properties. Camel milk has been used for the treatment of allergies to cow milk, diabetes, and autism. Camel milk helps decrease cholesterol levels in blood and improves metabolism. One of the most desirable food tastes is sweetness. However, the excessive ingestion of sugar negatively affects human health. Monk fruit sweetener is a natural, 0-calorie sweetener with many health-beneficial functions. Monk fruit sweetener helps decrease symptoms of asthma and diabetes, prevents oxidation and cancer, protects the liver, regulates immune function, and lowers glucose levels. Monk fruit sweetener is 100 to 250 times sweeter than sucrose. The objective of this study was to examine the influence of different concentrations of monk fruit sweetener on the physicochemical properties and microbiological counts of drinking yogurt made from camel milk. Camel milk drinking yogurt was produced with 0, 0.42, 1.27, and 2.54 g/L of monk fruit sweetener and stored for 42 d. The physicochemical characteristics and microbiological counts of yogurts were measured at d 1, 7, 14, 21, 28, 35, and 42. For the physicochemical characteristics, pH, titratable acidity, viscosity, and color [lightness-darkness (L*), red-green axis (a*), yellow-blue axis (b*), chroma (C*), and hue angle (h*)] values were evaluated. The counts of Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus acidophilus, coliforms, and yeast and mold were determined. Three replications were conducted. The sweetener addition significantly influenced pH, viscosity, and color (a*, b*, C*, and h*) values. Control samples had significantly higher pH values, lower viscosity, lower b* and C* values, and higher h* values than the samples with 1.27 and 2.54 g/L of monk fruit sweetener. Growth of S. thermophilus, L. bulgaricus, and probiotic culture L. acidophilus was not affected by the incorporation of monk fruit sweetener. Monk fruit sweetener can be added in camel milk yogurts as a health-beneficial 0-calorie sweetener.

Comparison of consumer-based methodologies for optimizing the development of new products: A case study with probiotic chocolate flavored milk

Several studies have reported that most new products do not achieve satisfactory results when launched on the market. There is a need to increase the efficiency of the methodologies used in the development of new products to increase success rates. Rapid sensory methodologies named Polarized Sensory Positioning (PSP), Check-all-that-apply (CATA), Projective mapping (PM) or Napping were applied to obtain sensory and hedonic information of a new product, probiotic-added chocolate flavored milk, aiming at determining preference guides that can be used to obtain a high overall liking level. It was possible to develop a probiotic chocolate flavored milk with general positive overall liking. The preferred sample was formulated with high content of sugar and chocolate, concluding that these characteristics are preference guides. The results supplied by the consumers using different methodologies were consistent, although the methodologies differed in their ability for sample differentiation. CATA methodology allowed better discrimination between samples than the other methodologies, followed by Projective Mapping, PSP with scales and triadic PSP. We could confirm that those rapid methodologies of sensory characterization are efficient when applied to product development.Practical applications Using those methodologies, it was possible to develop a probiotic chocolate flavored milk that meets both, consumer's expectations in relation to nutrition and taste and functionality. The methodologies proved to be efficient in characterizing consumer preference guides, and therefore fundamental to the development of a product with higher overall liking.

Sugar Reduction in Dairy Food: An Overview with Flavoured Milk as an Example

Owing to the public health concern associated with the consumption of added sugar, the World Health Organization recommends cutting down sugar in processed foods. Furthermore, due to the growing concern of increased calorie intake from added sugar in sweetened dairy foods, the present review provides an overview of different types and functions of sugar, various sugar reduction strategies, and current trends in the use of sweeteners for sugar reduction in dairy food, taking flavoured milk as a central theme where possible to explore the aforementioned aspects. The strength and uniqueness of this review are that it brings together all the information on the available types of sugar and sugar reduction strategies and explores the current trends that could be applied for reducing sugar in dairy foods without much impact on consumer acceptance. Among different strategies for sugar reduction, the use of natural non-nutritive sweeteners (NNSs), has received much attention due to consumer demand for natural ingredients. Sweetness imparted by sugar can be replaced by natural NNSs, however, sugar provides more than just sweetness to flavoured milk. Sugar reduction involves multiple technical challenges to maintain the sensory properties of the product, as well as to maintain consumer acceptance. Because no single sugar has a sensory profile that matches sucrose, the use of two or more natural NNSs could be an option for food industries to reduce sugar using a holistic approach rather than a single sugar reduction strategy. Therefore, achieving even a small sugar reduction can significantly improve the diet and health of an individual.

Consumer perception and sensory profile of probiotic yogurt with added sugar and reduced milk fat

The objective of this study was to determine the effect of different milk fat (MF, 0%, 1.5%, 3.3% (w/w)) or added sugar (AS, 0%, 3.5%, 7% (w/w)) levels on the sensory properties and consumer acceptability of probiotic set yogurts fermented by Streptococcus thermophilus, Bifidobacterium bifidum, and Lactobacillus delbrueckii subsp. bulgaricus. The experimental yoghurt samples were compared with a control containing AS, 7% and MF, 3.3%. A quantitative descriptive analysis was conducted using 12 semi-trained panelists to evaluate the sensory profile of yogurts by rating the intensity of sensory descriptors on a 10 unit scale. Consumer preferences was determined using a group untrained individuals (n = 31) by applying the hedonic test for preference. Sensory mapping and Principal Component Analysis (PCA) were conducted to obtain a comprehensive understanding of the consumer behavior. Partial Least Squares Regression (PLSR) was conducted to compare the sensory profiling, consumer preference and instrumental data. Descriptive data showed significant differences (p < 0.05) among the samples for 8 of the 15 attributes amalyzed, including flavor and texture parameters. PCA showed that more than 80% of consumers highly preferred the low-fat yogurt, basically due to its firmness. Overall, consumer preference decreases with the AS reduction. The sample containing zero sugar is the least preferred sample. The reduction of added sugar below 3.5% is a challenge in terms of retaining product quality.