Method of making dietetic sorbets and ice creams with a low sugar content obtained by introducing nanobubbles of air or another food grade gas into the production process

Abstract

The present invention relates to a method of making sorbet and / or ice cream with a low content of added sugars, comprising at least the following steps: - adding to a liquid mixture, water-based for sorbets or milk-based for ice creams, a plurality of nanobubbles of a gas usable in the food sector, with a size of between 1 and 1000 nm; - maturing said mixture by rapidly reducing the temperature to +5°C and homogenising the mixture; - adding at least one flavouring paste, e.g. coffee, hazelnut paste, zabaglione, or strawberries; - churning said mixture by cooling in a stirred receptacle.

Description

[0001] METHOD OF MAKING DIETETIC SORBETS AND ICE CREAMS WITH A LOW SUGAR CONTENT OBTAINED BY INTRODUCING NANOBUBBLES OF AIR OR ANOTHER FOOD GRADE GAS INTO THE PRODUCTION PROCESS

[0002] The present invention relates to a method of making dietetic sorbets and ice creams with a reduced sugar content.

[0003] In particular, the object of the present invention is a method of making dietetic sorbets and ice creams through the partial or total replacement of added sugars by means of a process that provides for the treatment of the liquid raw materials (water in the case of sorbets and milk in the case of ice creams) with systems adapted to produce therein nanobubbles of air or other gases usable in the food industry.

[0004] Ice cream represents one of the most popular food products worldwide and production is continually expanding in terms of the type and number of products.

[0005] In the international report entitled “Ice cream Market Size, Share & Trends Analysis Report”, issued by the specialised firm called Grand Review Research, it is reported that: “The global ice cream market size was valued at USD 79.0 billion in 2021 and is expected to expand at a compound annual growth rate (CAGR) of 4.2% from 2022 to 2030”. It is estimated in particular, therefore, that the world ice cream market was worth 81.8 billion dollars in 2022 and will be worth 114.7 billion dollars in 2030.

[0006] Today ice cream is thus a product known and sold all over the world, with growing popularity and consumption. The growing popularity of ice cream has stimulated the development of many variations in the preparation of ice cream mixtures, from the use of lactose-free compounds to ones with coconut milk, etc. It can clearly be foreseen that, in the near future, ice cream manufacturers will introduce new varieties among their products to satisfy an increasingly complex demand and to be able to introduce themselves to new market segments, competing with other types of products. Another decisive variable to be considered is that consumer demand is heading increasingly towards a health-oriented approach and thus towards ice creams that are as low-calorie as possible and least harmful to the human body.

[0007] In this complex, expanding context, it is possible to highlight that there exist 3 main types of sorbet and ice cream production, artisanal, industrial and production that exploits innovative methods:

[0008] A) Artisanal production

[0009] The raw materials used in artisanal ice cream production are standard raw materials such as water, milk and milk derivatives, eggs and egg derivatives, sugar and sweeteners, stabilising agents, gelling agents, emulsifying agents, plant fibres, and edible flavourings and dyes, be they natural, artificial or synthetic. These raw materials, appropriately mixed, make up the mixture to be processed.

[0010] As regards the raw materials used in artisanal sorbet production, it should be considered that both artisanal and industrial sorbet preparations differ from ice cream preparations only in terms of the raw materials used: fatty substances, i.e. milk and milk derivatives and eggs and egg derivatives are lacking in sorbets. In sorbets the liquid in which the various ingredients are dissolved is water rather than milk.

[0011] A first artisanal method of making ice cream is the following, made up of the following steps: step of pasteurising the mixture to be processed with temperatures ranging from 65°C for 30 minutes (low-temperature pasteurisation) to 85-90°C for about 60-90 seconds (high-temperature pasteurisation); maturation step, which consists in rapidly reducing the temperature of the mixture to +5 °C and the homogenisation thereof; addition of the various “flavouring pastes” (such as coffee, hazelnut paste, zabaglione, strawberries, etc.); final churning step, which consists in stirring and simultaneously cooling the mixture inside a cylindrical chamber. The surface of the churning chamber is on the one hand continuously scraped with specific metal blades called scrapers and on the other hand continuously cooled to bring the temperature of the mixture to values below 0°C. This is to enable a “cream” or frozen paste to be obtained, wherein only part of the free water making up the mixture remains in a liquid state, whereas the remaining water solidifies in the form of small ice crystals. During the churning process, this “cream” incorporates air in the form of macro- and microbubbles (diameter larger than 50 microns); the amount of air incorporated in this way is approximately 25-35% by volume relative to the volume of the initial liquid mixture. A second artisanal method of making ice cream differs from the one described above in that it skips the step of reducing the temperature of the mixture just pasteurised, which in this case goes directly from the pasteurisation step (be it low-temperature or high-temperature pasteurisation) to the churning step.

[0012] B) Industrial production

[0013] The raw materials of industrial ice cream are the same as those of artisanal ice cream.

[0014] The pasteurisation, temperature reduction and homogenisation (maturation) processes are identical to the ones described above for artisanal production. Subsequently, however, in the case of industrial production, the mixture is pumped into a machine called a “continuous freezer”, where appropriately filtered and metered air is injected directly into the churning cylinder. This treatment assures an increase in the amount of air incorporated into the ice cream, which in this manner can reach 120% in industrially produced ice cream, relative to the volume of the initial liquid mixture.

[0015] C) Innovative production methods

[0016] For several years now, new methods of making ice cream, which exploit in particular technologies and processes differing from the classic ones, have been becoming more widespread. For example, patents such as CN105285308A “A movable automatic control ice cream machine”, CN204014624U “Molecular ice cream equipment”, US7455868B2 “Apparatus and method for making ice cream products”, and US2009 / 0053375A1 “System and method for making blended frozen products with liquid nitrogen” provide for the use of liquid nitrogen for the ice cream refrigeration steps, often, however, with non-optimal results in terms not only of homogeneity, but also of process energy efficiency.

[0017] Irrespective of the production method used, one of the key aspects in order to be able to obtain a high-quality ice cream is that, during the cooling of the mixture in the churning step, it is necessary to limit the growth in the size of the ice crystals as much as possible. If, in fact, the size of the ice crystals were large, solid blocks of ice would form inside the churner, and this would preclude the possibility of obtaining a soft, creamy, homogeneous final product. It is thus necessary to avoid the formation of large ice crystals.

[0018] This result is obtained mainly in two ways. The first method consists in lowering the freezing point of the mixture, which is obtained by exploiting the colligative properties of the substances soluble in it, and mainly of the added sugars. The second method, by contrast, consists in the use of the scraper blades of the cooled chamber which, by continuously removing the ice that forms on the walls thereof, mechanically impedes the enlargement of the ice crystals.

[0019] At the present state of the art, in both cases and both for artisanal methods and industrial ones, this objective is achieved by adding a high content of sugars (sucrose, fructose, and glucose the most common), approximately 10-30% by weight in the case of sorbets and 10-20% by weight in the case of ice creams, to the mixtures prior to cooling.

[0020] The sugars have the aim not only of making these products sweet to the taste, but also and above all of making their production possible. In fact, as mentioned, the added sugars lower the freezing point of the mixtures to be cooled and during the churning step they impede an increase in the size of the ice crystals which, if their growth is not impeded, would considerably reduce the typical softness of the finished product, rendering it a grainy solid rather than soft and homogeneous as demanded.

[0021] For this precise reason, in sorbets and ice creams, unlike other sweetened foods, sugars such as sucrose, glucose, fructose or also other disaccharides, cannot be replaced by other sweeteners. In fact, the latter, having a much higher sweetening power in general than traditional sugars (sucrose, fructose and glucose and other disaccharides), are used in very low amounts and precisely for this reason they are not able to influence cryoscopic characteristics of the mixture, i.e. the freezing point thereof. In fact, the lowering of the freezing point of the solutions is directly tied to the number of dissolved molecules (cryoscopic effect). To date, this phenomenon has made it necessary to rely on sugars added in large amounts to lower the freezing point of milk-based mixtures in order to produce ice creams or water-based ones to produce sorbets.

[0022] It is well known, however, that sugars represent a dietetic problem. Not only can they cause metabolic problems tied to their absorption (blood sugar concentration), but they also interfere with the metabolism of fats, increasing their deposit in the body. Moreover, they are responsible for dental problems (i.e. caries), which may in turn lead to problems of digestion and nutrient absorption. The organisations in charge of food safety and hygiene around the world thus strongly recommended reducing the intake of added sugars in the daily diet. This represents a major limit to the consumption of sorbets and ice creams.

[0023] In Europe, the proportion of overweight people remains high and about 7% of European healthcare expenditure is employed in the treatment of pathologies connected to obesity, such as diabetes, high blood pressure, cardiovascular diseases, etc. Overweight and obesity, which are defined on the basis of the Body Mass Index (if this value exceeds a value of 25, one is defined overweight; if it exceeds a value of 30, one is obese), represent a phenomenon that concerns children and adults indistinctly. The data collected by the Childhood Obesity Surveillance Initiative (COSI) of the WHO European Region, in a sample of children ranging in age from 6-9 years, show that the prevalence of overweight ranges from 18% to 57% among males and from 18% to 50% among females; whereas 6-31 % of boys and 5-21 % of girls are obese. In Italy, “OKkio alia salute 2014”, a system for monitoring the dietary habits and physical activity of primary school children (6-10 years), revealed that 20.9% of children are overweight and 9.8% of children are obese, a slight decrease from 22.2% and 10.6% in 2012. Undeniably, in recent years, social, economic, and demographic transformations have significantly modified lifestyles and, consequently, the established eating habits.

[0024] The World Health Organization (WHO) estimates that obesity has tripled worldwide since 1975 (Source: World Health Organization, https: / / www.who. int / news-room / fact-sheets / detail / obesity-and-overweight) and that in 2016 over 1.6 billion adults, i.e. 39%, were overweight, and 650 million of these were obese. Moreover, the WHO deems that by now obesity claims more victims worldwide than hunger. However, the same WHO affirms that obesity can be prevented through a lower intake of high-calorie foods and more physical exercise.

[0025] In conclusion, sorbets and ice creams produced in such a way as to drastically decrease the added sugar content, without, however, modifying the appearance, consistency and other organoleptic characteristics, may significantly contribute to preventing obesity.

[0026] The solution according to the present invention fits into this context; it proposes a process applicable to both the artisanal and industrial production of sorbets and ice creams, whereby the added sugars are partially or totally replaced with nanobubbles of air or another food grade gas such as nitrogen, carbon dioxide or other inert gases. The present invention is based on the ability of nanobubbles of air or another food grade gas to impede, in the cooling steps, the growth in the size of the ice crystals of the mixtures making up sorbets and ice creams so as to replace the analogous effect exerted by added sugars.

[0027] Nanobubbles are gas bubbles within a liquid phase, whose diameter is in the order of nanometres; more precisely, nanobubbles are defined as gas bubbles with a diameter ranging between 1 and 1 ,000 nanometres (nm).

[0028] In particular, considering that 1 micron = 1 / 1 ,000 of a millimetre = 1 ,000 nanometres, one has the following classification:

[0029] • macrobubbles or normal bubbles: diameter > 1 ,000 microns;

[0030] • microbubbles: diameter between 1 ,000 and 50 microns;

[0031] • sub-microbubbles: diameter between 50 microns and 1 micron;

[0032] • nanobubbles: diameter < 1 micron, typically between 0.1 and 0.2 microns

[0033] (i.e. between 100 and 200 nanometres),1although nanobubbles with a diameter of less than 100 nanometres are common.

[0034] Due to their nanometric diameter, nanobubbles in suspension within a liquid phase show very interesting, absolutely original physical characteristics, very different from the ones shown by the microbubbles or macrobubbles normally present in sorbets and ice creams and foods in general.

[0035] The most important characteristics of nanobubbles include a very high internal pressure, which is compensated by interactions of an electrochemical type which arise between the liquid containing them and the surface of the nanobubbles themselves. A fundamental characteristic of nanobubbles within liquids is the long time for which they remain within the liquid phase containing them, unlike what occurs in the case of micro- and macrobubbles, which rise quickly to the liquid surface and explode upon contact with the latter. This is due to the fact that the abovementioned interactions of an electrochemical type stabilise the nanobubbles, preventing them from rising to the surface, exploding and thus disappearing from the mixture. This stability over time guarantees their use in many food products. Such stability is also tied and correlated to the temperature of the system and decreases as the temperature increases. Their dependence on temperature, i.e.

[0036] ‘ Tao, D . Role of bubble si ze in flotation of coarse and fine particles— A review . Sep . Sci . Technol . 2005 , 39 , 741-760 . their greater stability at low temperatures, is an advantage in the case of their application to the production of sorbets and ice creams.

[0037] However, even at room temperature nanobubbles can remain in liquids for weeks or even months.

[0038] There exist various methods for producing gas nanobubbles in water or other liquids, such as by application of the Venturi effect to a liquid-gas mixture,2hydrodynamic cavitation,3particular chemical reactions,4ultrasonic oscillation,5or electrolysis.6However, reasons tied to energy consumption, difficulty of installation and instrument maintenance make the latter methods more complex and less suitable for continuous industrial use, whereas the system of production by hydrodynamic cavitation appears to be the simplest and most effective.7The method based on the application of the Venturi effect also appears to be among the least complex and most suitable for industrial development.

[0039] 2In a mixture of gases in a liquid in the form of macro- or microbubbles, subjected to specific fluid-dynamic conditions, i.e. a rapid change in the local pressure and velocity conditions, nanobubbles may form as a result of breakage of the existing micro- and macrobubbles.

[0040] 3Nazari, S.; Hassanzadeh, A. The effect of reagent type on generating bulk sub-micron (nano) bubbles and flotation kinetics of coarse-sized quartz particles. Powder Technol. 2020, 374, 160-171.

[0041] 4Svetovoy, V.B. Spontaneous chemical reactions between hydrogen and oxygen in nanobubbles. Curr. Opin. Colloid Interface Sci. 2021, 52, 101423.

[0042] 5Yasuda, K.; Matsushima, H.; Asakura, Y. Generation and reduction of bulk nanobubbles by ultrasonic irradiation. Chem. Eng. Sci. 2019, 195, 455-461.

[0043] 6Kikuchi, K.; Nagata, S.; Tanaka, Y.; Saihara, Y.; Ogumi, Z. Characteristics of hydrogen nanobubbles in solutions obtained with water electrolysis. J. Electroanal. Chem. 2007, 600, 303-310 .

[0044] 7Recent Developments in Generation, Detection and Application of Nanobubbles in Flotation, Sabereh Nazari, Ahmad Hassanzadeh, Yaqa He, Hamid Khoshdast and Przemyslaw B. Kowalczuk, Minerals 2022, 12, 462. https: / / doi.org / 10.3390 / minl2040462 The use of nanobubbles in ice cream has been studied, for example, in the article “Capturing the impact of nanobubble liquid in enhancing the physical quality of ice cream” by Norhafizah Mohamad Khaira et al. This article reports a scientific study on the effect of nanobubbles in foods and in ice cream in particular. According to the authors, an ice cream made with a liquid containing nanobubbles has different characteristics from a traditional ice cream; in particular, the liquid with nanobubbles allows the chemical and physical properties of the ice cream to be modified so as to obtain a greater capacity of the ice cream to maintain its form over time (obstacle to melting of the ice cream).

[0045] Cocchi et al., in Italian patent IT201800006332 and European patent EP3581034, claim a machine for making food products which comprises, among other things, at least one device, not better specified, capable of generating gas micro- or nanobubbles and releasing such micro- or nanobubbles into the preparation, including ice creams.

[0046] There are other patents or publications on the same subject which enable us to affirm that the use of air or gas bubbles of nanometric dimensions in foods is well known and has all the potential of modifying the chemical and physical characteristics of preparations into which they are blown.

[0047] The present invention, compared to such prior techniques, aims by contrast to claim a method of making sorbets and ice creams which enables the sugars used by the traditional industry to be limited or eliminated, with two important results: on the one hand, an improvement in health conditions in consumers of ice cream, with important effects in the clinical / healthcare sector, and on the other hand the possibility of expanding the pool of consumers by including among them also those who for health reasons cannot take in large amounts of sugars.

[0048] The method of preparation of the present invention makes it possible to use nanometre-sized bubbles of air or another gas usable in foodstuffs as a partial or total replacement for sugars in the preparation, both artisanal and industrial, of both sorbets and ice creams.

[0049] This method of making sorbets and ice creams with nanobubbles of air, nitrogen, carbon dioxide or other gases usable in the food sector offers the possibility of making sorbets and ice creams with a reduced content of added sugars. In fact, nanobubbles, because of their greatly reduced size and the fact that they persist for a long time within liquids, since they do not rise to the surface due to gravity, or they rise to the surface a after very long time, and in any case much longer than that of the cooling processes used in artisanal and industrial sorbet and ice cream making, impede the increase in size of ice crystals during cooling, thus making it possible to greatly limit or even eliminate the need to add sugars or other soluble compounds.

[0050] Another advantage of the present invention is that it allows for producing dietetic ice creams and sorbets with a reduced sugar content and organoleptic characteristics equivalent to or even better than those of traditional ice creams and sorbets obtained with the addition of sugars. The lower sugar content thus obtained enables a lower calorie contribution of the food “ice cream” and consequently the possibility of increasing the pool of potential consumers by decreasing the risk of obesity linked to the intake of large amounts of sugars and extending the consumption of this product to those who suffer from problems tied to sugar metabolism (diabetes).

[0051] Another advantage of the present invention is that the use of nanobubbles of air or another food grade gas allows for an increase in the total amount of air contained in the finished sorbet or ice cream, with a decrease in the cost thereof, the consistency being equal.

[0052] If in fact it is technically possible to increase the amount of air present in a sorbet or ice cream simply by blowing in air, by means of a simple air compressor, into the base mixture before the cooling step, in this case the added air would be present in the form of macrobubbles or microbubbles and in this case, besides the increase in volume, the weight being equal, the effect on the finished product would be a marked decrease in physical consistency, something that is negative for the consumer. The use of nanobubbles of air or another food grade gas, by contrast, allows the amount of air present in the sorbets and ice creams to be increased, thereby increasing the volume thereof, the weight being equal, without however negatively impacting the consistency of the finished product.

[0053] An additional advantage of the present invention, if air is used as the gas to produce the nanobubbles, is that the reduction or total elimination of sugars in the preparation of sorbets and ice creams enables a clear economic and environmental advantage, sugars being substances with a high economic cost and major environmental impact due to their production, transport and storage, which are operations with a significant environmental impact. Finally, the present invention enables a reduction in processing costs, since sorbets and ice creams produced from water or milk to which nanobubbles of air or another food grade gas are added as described above have a lower viscosity compared to mixtures devoid of such nanobubbles and rich in added sugars.

[0054] The solution of the present invention, therefore, provides for the partial or total replacement of added sugars in the preparation of ice cream or sorbet with nanobubbles of air or another gas usable in the food industry. The generation of nanobubbles within the liquids, water or milk, used in both artisanal and industrial sorbet and ice cream making, can be achieved by means of one of the methods mentioned previously, in particular the one that exploits the Venturi effect.

[0055] The liquid used to make sorbet or ice cream, thus water or milk, regulated in terms of pressure and flow rate, is delivered with the aid of a fluid-dynamic pump, i.e. hydraulic machine, in a continuous manner, that is, without interruptions in flow, towards a specially dimensioned apparatus for generating nanobubbles (generator) based on the Venturi effect, or by ultrasound or another available technology. If a generator based on the Venturi effect is used, a flow of air or another food grade gas is delivered under a controlled pressure and flow rate to the aforesaid generator apparatus.

[0056] In particular, for the production of an amount of nanobubbles sufficient to ensure a significant effect as regards the freezing properties of the treated fluids (water or milk), it is necessary that the pressure of that fluid be equal to at least 2 bar, preferably between 2 and 2.2 bar, whereas the pressure of the gas (air, nitrogen or another food grade gas) is slightly higher (by about two tenths of a bar) to ensure that the gas itself is able to exceed the pressure of the liquid and that it can thus penetrate into it inside the generator by virtue of the Venturi effect.

[0057] As regards the gas flow at the specified pressure, it must be about 2.2 litres / m inute. With pressures of either the liquid or gas or gas flows below these values, the quantity of nanobubbles produced in the liquid would in fact be insufficient to ensure a perceptible improvement in the properties of the liquid used when cold and thus the replacement of sugars as antifreeze substances.

[0058] By setting the instrument with these values, in fact, it is possible to obtain a milk- or water-based ice cream that remains soft and is thus also usable at a temperature of -5 °C without the addition of sugars or other substances capable of lowering the freezing point of the water through a cryoscopic effect. In the generator apparatus, the nanobubbles are produced within the liquid phase.

[0059] Therefore, the fluid thus composed can be delivered either towards a collection receptacle or again towards the generator apparatus, thereby extending the total treatment time in order to increase the concentration of nanobubbles within the liquid phase by means of a recirculation system.

[0060] Upon the conclusion of the treatment cycle, whose duration can be regulated as desired, the fluid can be delivered towards a collection receptacle and the process of enrichment with nanobubbles ended.

[0061] Alternatively, thanks to the predefined pressure and flow rate settings, the system can work in a continuous mode, varying the percentage of treated fluid which is again delivered to the generator apparatus by means of special regulating valves.

[0062] The ingredients necessary for proceeding in the subsequent steps of artisanal or industrial ice cream making as previously illustrated are therefore added to the fluid thus treated and enriched with nanobubbles of air or another food grade gas.

Claims

CLAIMS1 ) A method of making sorbets and / or ice creams with a low content of added sugars, comprising at least the following steps:- adding to a liquid mixture, water-based for sorbets or milk-based for ice creams, a plurality of nanobubbles of a gas usable in the food sector, with a size of between 1 and 1000 nm;- maturing said mixture by rapidly reducing the temperature to +5°C and homogenising the mixture;- adding at least one flavouring paste, e.g. coffee, hazelnut paste, zabaglione, or strawberries;- churning said mixture by cooling in a stirred receptacle.2) The method of making sorbets and / or ice creams according to the preceding claim, characterised in that it comprises, for the preparation of ice creams, a preliminary step of low-temperature pasteurisation at 65°C for 30 minutes or high-temperature pasteurisation at 85-90°C for 60-90 seconds.3) The method of making sorbets and / or ice creams according to any one of the preceding claims, characterised in that all or part of the added sugars (sucrose, fructose, glucose or other monosaccharides or disaccharides) are replaced by nanobubbles of air or of another food grade gas with a size of between 1 and 1 ,000 nanometres.4) The method of making sorbets and / or ice creams according to any one of the preceding claims, characterised in that said gas usable in the food sector is selected from air, nitrogen, carbon dioxide or other inert gases usable in the food sector or a combination thereof.5) The method of making sorbets and / or ice creams according to any one of the preceding claims, characterised in that said plurality of nanobubbles is obtained by means of a treatment system for adding nanobubbles, wherein a hydraulic machine continuously delivers said gas usable in the food sector towards a nanobubble generator.6) The method of making sorbets and / or ice creams according to the preceding claim, characterised in that the treatment system for adding nanobubbles exploits a nanobubble generator based on the Venturi effect.7) The method of making sorbets and / or ice creams according to claim 5, characterised in that, to produce nanobubbles, the treatment system for adding nanobubbles exploits an ultrasound generator or another system suitable for generating nanobubbles or a combination thereof.8) The method of making sorbets and / or ice creams according to any one of the preceding claims, characterised in that it comprises a step of regulating the concentration of said plurality of nanobubbles in the liquid mixture by regulating the pressure and flow of the liquid to be treated and the gas to be introduced as nanobubbles, as well as by regulating the number of passages in the system for generating the nanobubbles themselves.9) The method of making sorbets and / or ice creams according to the preceding claim, characterised in that it comprises a step of regulating the pressure of said plurality of nanobubbles to at least 2 bar.