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Title:
BIODEGRADABLE STRAWS FOR THE SUCTION OF DRINKS AND LIQUID FOODS
Document Type and Number:
WIPO Patent Application WO/2020/212417
Kind Code:
A1
Abstract:
Biodegradable dry pasta straws for the suction of drinks and liquid foods, having a Maillard reaction compound content, expressed as mg/kg of quinine sulfate, equal to at least 1.4, obtainable by a process which comprises the steps of: a) kneading regrind dry pasta, or a mixture consisting of regrind dry pasta and durum wheat semolina, in a weight ratio of at least 3:7, thus obtaining a dough with a moisture content of 30-35%; b) extruding the dough through a die to form fresh pasta tubes with a circular section; c) subjecting the fresh pasta tubes to drying and cutting steps, thus obtaining dry pasta straws with a moisture content lower than or equal to 13.0%; a method is also described for the upgrading of scraps and waste from production plants of dry pasta from durum wheat semolina, comprising a step of grinding said scraps and waste, so as to obtain regrind dry pasta, which is subjected to the above described steps, in order to obtain the above described biodegradable dry pasta straws.

Inventors:
BERGAMINI ELENA (IT)
BACCHI ANNALISA (IT)
BERTI CLAUDIA (IT)
Application Number:
PCT/EP2020/060583
Publication Date:
October 22, 2020
Filing Date:
April 15, 2020
Export Citation:
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Assignee:
BARILLA FLLI G & R (IT)
International Classes:
A23L7/109; A47G21/18
Domestic Patent References:
WO2020044049A12020-03-05
WO2008076144A12008-06-26
Foreign References:
GB865615A1961-04-19
US20050109857A12005-05-26
DE202016005545U12016-11-11
US20050260304A12005-11-24
GB865615A1961-04-19
AU2018101026A42018-08-23
Other References:
AMERICAN ASSOCIATION OF CEREAL CHEMIST, INC: "Pasta Containing Regrinds: Effect of High Temperature Drying on Product Quality", 24 May 1995 (1995-05-24), XP002796603, Retrieved from the Internet [retrieved on 20191219]
FANG, K.KHAN, K.: "Pasta containing regrinds: effect of high temperature drying on product quality", CEREAL CHEM., vol. 73, no. 3, pages 317 - 322, XP002796603
S. MATIACEVICH ET AL., FOOD CHEMISTRY, vol. 95, 2006, pages 423 - 430
Attorney, Agent or Firm:
FERRECCIO, Rinaldo (IT)
Download PDF:
Claims:
CLAIMS

1. Biodegradable dry pasta straws for the suction of drinks and liquid foods, having a Maillard reaction compound content, expressed as mg/ kg of quinine sulfate, equal to at least 1.4, obtainable by a process which comprises steps of: a) kneading regrind dry pasta, or a mixture consisting of said regrind dry pasta and durum wheat semolina, in a weight ratio of at least 3: 7, and optional additional food ingredients, with water, thus obtaining a dough with a moisture content of 30-35%; b) extruding said dough through a die to form fresh pasta tubes with a circular section; c) subjecting said fresh pasta tubes to successive drying and cutting steps or to successive cutting and drying steps, thus obtaining dry pasta straws with a moisture content lower than or equal to 13.0%.

2. The biodegradable straws according to claim 1 , wherein said mixture of regrind dry pasta and durum wheat semolina of step a) comprises at least 80% by weight of regrind dry pasta.

3. The biodegradable straws according to claim 1 or 2, wherein said optional additional food ingredients are selected from natural dyes and vegetable extracts, either dried or in puree, gluten and/or technological adjuvants.

4. The biodegradable straws according to any one of claims 1-3, characterized by having an internal diameter of 4.0-8.0 mm and an external diameter of 5.0-9.0 mm.

5. The biodegradable straws according to claim 4, characterized by having a thickness of 0.8- 1.2 mm.

6. The biodegradable straws according to claim 4 or 5, characterized by having a length of 150-250 mm.

7. The biodegradable straws according to any one of claims 1-6 characterized in that they have a plurality of longitudinal ridges on their outer surface.

8. The biodegradable straws according to claim 7, wherein said longitudinal ridges are 10-25.

9. The biodegradable straws according to any one of claims 1-8, wherein the particle size of the regrind dry pasta is in the range of 180-400 pm.

10. Use of scraps and waste from production plants of dry pasta from durum wheat semolina, for the production of biodegradable straws for the suction of drinks and liquid foods.

1 1. Method for the upgrading of scraps and waste from production plants of dry pasta from durum wheat semolina, comprising the steps of: a) grinding said scraps and waste so as to obtain regrind dry pasta with a particle size in the range of 180-400 pm, b) kneading said regrind dry pasta or a mixture consisting of said regrind dry pasta and durum wheat semolina, in a weight ratio of at least 3: 7, and optional additional food ingredients, with water, thus obtaining a dough with a moisture content of 30-35%; c) extruding said dough through a die to form fresh pasta tubes with a circular section; d) subjecting said fresh pasta tubes to successive drying and cutting steps or to successive cutting and drying steps, thus obtaining biodegradable dry pasta straws with a moisture content lower than or equal to 13.0%, suitable for sucking drinks and liquid foods.

12. The method according to claim 1 1, wherein said regrind dry pasta has a content of compounds of the Maillard reaction, expressed as mg/ kg of quinine sulfate, equal to at least 0.7, generally between 0.8 and 1.0, typically around 0.9.

13. The method according to claim 12, wherein said biodegradable dry pasta straws have a content of compounds of the Maillard reaction, expressed as mg/kg of quinine sulfate, equal to at least 1.4.

14. The method according to any one of claims 1 1- 13, wherein said mixture of regrind dry pasta and durum wheat semolina of step a) comprises at least 80% by weight of regrind dry pasta.

15. The method according to any one of claims 1 1- 14, wherein said optional additional food ingredients are selected from natural dyes, vegetable extracts, either dried or in puree form, gluten and/or technological adjuvants.

Description:
Title: Biodegradable straws for the suction of drinks and liquid foods

DESCRIPTION

Field of application

The present invention relates to a biodegradable straw for the consumption of drinks and liquid foods.

Prior art

The use of plastic straws for the consumption of drinks, cocktails, fruit juices, American coffee, liquid foods, etc., is well known. It is unfortunately equally known that these plastic straws are one of the main causes of pollution of the waters of seas, rivers and lakes from plastic materials. From the website of the Plastic Pollution Coalition organization (https:/ /www. plasticpollutioncoalition.org/no-straw-please) we learn that in the United States of America alone, more than 500 million plastic straws are used per day, which are thrown into the garbage immediately after consumption, thus becoming a dangerous source of pollution from plastic.

Precisely for this reason, plastic straws appear, along with plastic plates and cups, among the various disposable plastic utensils whose use will be forbidden in the European Union as of 2021, further to the very recent approval of the CE directive 5483/ 19.

Several alternatives to plastic straws, including paper straws, have already been proposed. The latter, however, have unsatisfactory performance since they tend to absorb the liquid with which they come into contact, with consequent compromise of their structural and performance characteristics.

From publication DE 20 2016 005 545 U edible straws based on fresh fruit are also known, which may also contain dried fruit and which may have a stabilizing coating against water, consisting of alginate or carnauba wax.

From WO 2008/76144 straw-shaped candies are known. US 2005/0260304 also describes edible candy-based straws, comprising two concentric tubular elements, whose internal element is of soft candy and the outer element is of hard candy.

GB 865 615 discloses a drinking tube formed as a dried extrusion of flour paste similar to that used in the production of macaroni, but containing an admixture of sugar and fruit juice, said tube being preferably treated with an edible water-repellant substance, such as a substantially tasteless vegetable oil.

Then there is AU 2018/ 101026 patent application, which describes an edible straw of whole wheat pasta or gluten-free pasta.

It is also known that in the industrial production of dry pasta, far from negligible quantities of scraps and other production waste such as broken or cracked pasta shapes are produced, which can be collectively called pasta residues. Although it is allowed to regrind these residues and mix them, within certain percentage content limits and within the plant where they were produced, to the durum wheat semolina from which pasta is produced, this operation is not always carried out since the addition of regrind dry pasta residues to the semolina causes a certain worsening of the organoleptic and structural characteristics of the pasta produced, when the same is cooked for consumption.

For this reason, the bulk of the aforementioned pasta residues is generally used for feeding farm animals where it would be desirable to find a new way to reuse these residues, which would entail a greater added value compared to reuse in animal feed.

The scientific article “Pasta containing regrinds: effect of high temperature drying on product quality” by Fang, K. Khan, K. (Cereal Chem. 73(3):317-322) relates to low, high, and ultra-high temperature dried (LTD, HTD, UTD) pasta regrinds used in several replacement level with semolina to produce spaghetti and elbow macaroni; in particular, the products were dried at 40°C (low), 73°C (high) and 90°C (ultra-high) and evaluated for quality factors such as color, firmness, cooking loss and cooked weight. This document does not disclose pasta straws obtained by pasta regrinds.

Summary of the invention

In view of the known technique illustrated above, the technical problem underlying the present invention has been that of providing an ecological alternative to plastic straws used for the consumption of food liquids and drinks, which, in addition to being completely biodegradable and therefore with zero environmental impact, also entailed an upgrading of a waste material, such as production scraps and waste from pasta.

Said technical problem was solved, according to the invention, by providing biodegradable dry pasta straws for the suction of drinks and liquid food, having a Maillard reaction compound content, expressed as mg/kg of quinine sulfate, equal to at least 1.4, obtainable by a process which comprises the steps of: a) kneading regrind dry pasta, or a mixture consisting of said regrind dry pasta and durum wheat semolina, in a weight ratio of at least 3:7, as well as optional additional food ingredients, with water, thus obtaining a dough with a moisture content equal to 30-35%; b) extruding said dough through a die to form fresh pasta tubes with a circular section; c) subjecting said fresh pasta tubes to successive drying and cutting steps or to successive cutting and drying steps, thus obtaining dry pasta straws with a moisture content less than or equal to 13.0%.

“Fresh pasta”, in the context of the present patent application, means pasta obtained by mixing, and successive kneading with water, regrind durum wheat dry pasta, or a mixture of regrind durum wheat dry pasta and durum wheat semolina, in the weight ratios indicated above.

“Dry pasta straws” means the straws obtained from“fresh pasta” tubes as above defined, further to cutting and drying operations.

Preferably, the mixture of step a) comprises at least 80% by weight of regrind dry pasta.

The optional additional food ingredients referred to in step a) are preferably selected from natural dyes and vegetable extracts, either dried or in puree, gluten and/or technological adjuvants.

The biodegradable straws according to the invention preferably have an internal diameter of 4.0-8.0 mm, an external diameter of 5.0-9.0 mm, a thickness of 0.8- 1.2 mm and a length of 150-250 mm.

Preferably, the dry pasta straws according to the invention have a plurality of longitudinal ridges on their outer surface, conveniently in number of 10-25.

Preferably, the particle size of the regrind dry pasta is in the range of 180- 400 pm.

The present invention further relates to the use of scraps and waste from production plants of dry pasta from durum wheat semolina, for the production of biodegradable straws for the suction of drinks and liquid foods.

In another aspect thereof, the present invention relates to a method for the upgrading of scraps and waste from production plants of dry pasta from durum wheat semolina, comprising the steps of: a) grinding said scraps and waste so as to obtain regrind dry pasta with a particle size in the range of 180-400 pm, b) kneading the regrind dry pasta or a mixture consisting of said regrind dry pasta and durum wheat semolina, in a weight ratio of at least 3:7, and optional additional food ingredients, with water, thus obtaining a dough with a moisture content of 30-35%; c) extruding the dough through a die to form fresh pasta tubes with a circular section; d) subjecting said fresh pasta tubes to successive drying and cutting steps or to successive cutting and drying steps, thus obtaining biodegradable dry pasta straws with a moisture content lower than or equal to 13.0%, suitable for sucking drinks and liquid foods.

Preferably the raw material, regrind dry pasta, used in the method according to the invention has a content of compounds of the Maillard reaction, expressed as mg/kg of quinine sulfate, equal to at least 0.7, generally between 0.8 and 1.0, typically around 0.9.

The biodegradable dry pasta straws obtained with the above method preferably have a content of compounds of the Maillard reaction, expressed as mg/kg of quinine sulfate, equal to at least 1.4.

The mixture of regrind dry pasta and durum wheat semolina of step a) preferably comprises at least 80% by weight of regrind dry pasta.

The above optional additional food ingredients are preferably selected from natural dyes, vegetable extracts, either dried or in puree form, gluten and/or technological adjuvants.

The particle size of the regrind dry pasta preferably has the average particle distribution illustrated in the following Table 1, compared to durum wheat semolina.

TABLE 1

Where: V.R. = Veil refusal; or the part by weight % that remains on the“veil” or sieve with the indicated mesh light and v.p. = veil passage; or the part by weight % that is collected on the plate below the veil or sieve with 180 mpi mesh light.

The sample is sieved under defined conditions and the quantities that pass under the sieves with different mesh lights are determined, then expressed as a percentage of particles on the weight of the sample.

The straws according to the present invention are suitable for use with any kind of food liquid, cold or hot, from simple water to soft drinks, sparkling or non-sparkling, to alcoholic beverages, such as wine, cocktails, fruit and vegetable juices and smoothies, to vegetable soups, since they are provided with adequate resistance to imbibition and remain open, and therefore functioning, even after immersion for a time equal to 40 minutes in a liquid.

If in the dough as referred to in step a) there are also natural dyes or colored vegetable extracts, it is possible to change the color of dry pasta straws according to contingent needs (for instance if one wishes to give straws an appropriate color for certain occasions, such as for instance a red color for straws to be used at Christmas time).

The presence of ridges or scratches on the outer surface of the straws according to the invention not only has an aesthetic function but also the function of further increasing the performance of the straws according to the invention. Indeed, as it will be illustrated hereinafter in detail, the presence of ridges on the outer surface of the straws reduces the very slight note of starch perceived when the smooth straws are brought to the mouth, as well as the tendency of the straw to adhere to the lips.

Therefore, the dry pasta straws according to the present invention constitute a valid ecological alternative to plastic straws and at the same time a good added value product obtained from a waste material, such as scraps from the production of dry pasta, for which no recovery and upgrading mode was available up to now.

The pasta straws according to the present invention may be produced with conventional equipment used in plants that produce dry pasta and using substantially the same process used for the production of dry pasta, which comprises the steps of dosing durum wheat semolina and water in a predetermined weight ratio in a first mixer at high speed, directing the outgoing mixture to a main mixer where a first kneading is carried out, feeding the dough into a vacuum mixer that extrudes the dough through a die with inserts to provide a determined pasta shape (in the specific case of the straw, the die provides the correct diameter and thickness to the cylindrical tube which the straw will be obtained from) .

Obviously, it is possible to use kneading and extrusion processes that are slightly different from the one mentioned above, also based on the equipment available in a given plant and on those that would become available with the evolution of technologies in the food industry.

The cutting and drying operations may be performed in two different sequences. The cutting operation of the cylindrical tubes extruded from the die may be first performed, followed by the drying in hot-air dryers equipped with perforated cages that transport the pasta into the dryer. Alternatively, the drawn product (cylindrical tubes), but not cut hanging on metal reeds, may be dried and then the cutting of the dried cylindrical tubes may be performed.

The sole difference with respect to the above-summarized conventional process consists of the different mixture fed to the first mixer, which in the case of the straws according to the present invention consists of regrind dry pasta and water or water and a mixture of regrind dry pasta/durum wheat semolina in a weight ratio equal to at least 3/7.

The scraps and waste from which the regrind dry pasta used in the method according to the present invention are obtained are recognizable from a chemical point of view, in comparison to the common durum wheat semolina by looking for two main markers, namely the extractability of proteins and the Maillard reaction compounds (“Maillard Reaction Products” - MRP).

Indeed, the dried regrind pasta has a content of extractable proteins that is lower than or equal to 80% of the total proteins present in the matrix whereas durum wheat semolina has a content of extractable proteins (or protein extractability) equal to around 100%.

The content of extractable proteins may be determined through the method described in the appendix at the bottom of the present description.

The regrind dry pasta used for the production of the biodegradable straws according to the present invention has a content of compounds (or markers) of the Maillard reaction that is equal to or greater than 0.7 mg/kg of quinine sulfate. Even in this second case the regrind dry pasta is recognizable from the common durum wheat semolina used to produce quality pasta, since the latter regularly has markers values of the Maillard reaction that are lower than or equal to 0.6 mg of quinine sulfate/ kg of dry pasta. The increased concentration of markers passing from semolina to regrind pasta is caused by the thermal stress that the pasta undergoes during the drying and that, conversely, a native semolina does not have, since it has never undergone heat treatments.

Furthermore, the regrind dry pasta obtained from the above scraps and waste usually has a relative moisture that is lower than the standard semolina: 9.5% against around 13.5% of durum wheat semolina. Brief description of the figures

Figure 1 is a radar chart that compares different properties of the straws according to the present invention with conventional plastic straws, when used for the suction of sparkling mineral water.

Figure 2 is a radar chart that compares different properties of the straws according to the present invention with conventional plastic straws, when used for the suction of still mineral water.

Detailed description

As above mentioned, in the production plants of durum wheat semolina pasta, quantities of scraps are produced (e.g. the curved parts of spaghetti and other long pasta shapes, which are removed at the end of the drying process), which are far from negligible and the same applies for broken or cracked pasta, which must be discarded before packing.

According to the Italian law, it is possible to re-grind these dry pasta scraps and waste and add them within certain limits to the durum wheat semolina used to produce pasta but, as already mentioned, this addition of regrind dry pasta to durum wheat semolina involves a certain worsening of the organoleptic and structural characteristics of the final dry pasta.

Indeed, during the drying, which involves a thermal treatment of pasta at temperatures of at least 50 °C, typically from 75 °C to 100 °C, the glucides and proteins contained in the pasta are subjected to the Maillard reaction, i.e. a non-enzymatic browning process that involves a complex series of reactions between amino acids with a free amino group and reducing sugars at high temperature.

As a result, by adding regrind dry pasta to the durum wheat semolina with which pasta is produced, a pasta is obtained, which at the end of the drying is darker than the pasta obtained from wheat semolina alone. Furthermore, also the protein component of the re-grind pasta (gliadin and glutenin, components from which gluten is formed by hydration during kneading) undergoes a certain denaturation and consequently, when using re-grind pasta in addition to durum wheat semolina, a pasta with lower consistency characteristics (“texture”) and less resistance to cooking is obtained.

With the present invention, a mode of reuse of the regrind pasta has been made available, for which the darker coloring, due to the Maillard reaction, and the denaturation of the protein component do not constitute drawbacks, as they have no impact on the function that the straws produced with the regrind pasta must carry out. Indeed, the latter do not necessarily need to have a light color and to be cooked in water, in fact they are not intended to be consumed by the user at all.

The presence in the straws according to the present invention of the Maillard reaction products in a clearly higher concentration than the conventional durum wheat semolina pasta constitutes a differentiation “marker” towards the latter.

In the intermediate stages of the Maillard reaction chain, fluorescent molecules that can be measured are formed. Fluorescence measurement has the advantage of being independent of the color of the sample and offers greater sensitivity with respect to other methods. In the advanced stages of the Maillard reactions, the compounds form cross-links with proteins or other aminogroups, thus giving rise to aggregates of fluorescent polymers, also called advanced glycation end products (AGE) .

The concentration of the Maillard reaction products may therefore be determined through a method based on the measurement of fluorescence, in particular through the method according to the publication S. Matiacevich et al. - Food Chemistry 95 (2006) 423-430, and the results are expressed as ppm or mg/ kg, based on a calibration curve obtained by measuring the fluorescence of solutions at different concentrations of quinine sulfates. As above mentioned, the product content of the Maillard reaction of the straws according to the present invention is equal to at least 1.4 (expressed as mg/kg of quinine sulfate) and is generally around 1.6- 1.8 whereas the product content of the Maillard reaction of durum wheat semolina is around 0.9.

The present invention will be further illustrated with reference to three example embodiments and to some comparative tests.

EXAMPLE 1

Using a small-scale pasta production plant, regrind dry pasta straws according to the invention were produced as follows.

13.5 kg of regrind dry pasta having the particle size shown in Table 2 below

TABLE 2

where:

V.R. = Veil refusal; or the part by weight % that remains on the“veil” or sieve with the indicated mesh light; and

v.p. = veil passage; or the part by weight % that is collected on the plate below the veil or sieve with 180 mpi mesh light were mixed, in an Italpast mixer, 1993 model MAC 60, kneading tank capacity 13 kg, average capacity 25 - 60 kg/h, to 1.5 kg of durum wheat semolina and 4.9 kg of water, for 20 minutes.

The mixer worked during the mixing at the following temperatures 38 °C tank, 38 °C cylinder, 42 °C head at the die level; being it a vacuum mixer, the vacuum is set at -9.6. 10 4 Pa (-960 mbar).

The homogeneous dough thus obtained was extruded, by applying an extrusion pressure of 85 bar, through a circular die having extrusion inserts with an extrusion lumen equal to 1. 150 mm of thickness. The cylindrical tubes exiting from the die were cut with a knife to a length of 1 meter and then placed in a heap on stainless steel reed supports and dried in a Bicella Alter dryer of 1995.

The temperature at the inlet of the dryer was 46 °C whereas the drying temperature was 82 °C and the final stabilization temperature was 40 °C. The tubes hanging on reeds were dried for 9 hours by hot air having a speed of 2 m/s. From the dried cylindrical tubes straws of length equal to 210 mm were obtained by cutting.

The straws thus obtained had an internal diameter of 6.86 mm, an external diameter of 8.00 mm and a thickness of 1. 14 mm.

The starting regrind dry pasta had a moisture of 9.6 g/ 100 g whereas the starting durum wheat semolina had a moisture of 13.7 g/ 100 g.

The starting regrind dry pasta had a Maillard product content, expressed as mg of quinine sulphate/ kg, equal to 0.8 whereas the starting durum wheat semolina had a content of these products equal to 0.6.

The final straws instead had a Maillard product content, expressed as mg of quinine sulfate/kg, equal to 1.6 whereas dry pasta straws produced starting from durum wheat semolina alone ( 15 kg of durum wheat semolina and 3.3 kg of water) under the same conditions and with the same plant as above had a content of these products equal to 0.9.

EXAMPLE 2

Using the same plant as of example 1, straws of regrind dry pasta according to the invention were produced starting from 10 kg of regrind dry pasta and 3.4 kg of water, under the same operating conditions indicated for example 1, using a circular die having inserts with an extrusion lumen equal to 1. 10 mm of thickness. Using the same experimental conditions as of example 1 , from the dried cylindrical tubes straws with a length equal to 150 mm were obtained by cutting. The straws thus obtained had an internal diameter of 5.55 mm, an external diameter of 6.51 mm and a thickness of 0.96 mm.

EXAMPLE 3

Using the same plant as of example 1 regrind dry pasta straws according to the invention were produced starting from 8 kg of regrind dry pasta, 2 kg of durum wheat semolina and 3.2 kg of water, under the same operating conditions indicated for example 1. Using the same experimental conditions as of example 1, from the dried cylindrical tubes straws with a length equal to 220 mm were obtained by cutting.

The straws thus obtained had an internal diameter of 7.00 mm, an external diameter of 8. 16 mm and a thickness of 1. 15 mm.

EXAMPLE 4

Using the same plant as of example 1 straws of regrind dry pasta according to the invention were produced starting from 9 kg of regrind dry pasta, 0.9 kg of durum wheat semolina and 3.3 kg of water, under the same operating conditions indicated for example 1, using a die for ridged pasta, adapted to create pasta tubes provided with 18 longitudinal ridges that are equidistant from each other on their outer surface. Using the same experimental conditions as of example 1, from the dried cylindrical tubes having 18 longitudinal ridges, ridged straws with a length of 210 mm were obtained by cutting.

The straws thus obtained had an internal diameter of 6.85 mm, an external diameter of 8.00 mm, a thickness of 1. 14 mm, with 18 longitudinal ridges equidistant from each other. EXAMPLE 5

The straws of regrind dry pasta referred to in examples 1 and 4 were used in the context of a comparison test with cocktail plastic straws having a length of 210 mm and an internal diameter of 8.00 mm. A panel of trained tasters were asked to express their assessments on a series of sensory characteristics related to the sucking of 100 ml of sparkling and still mineral water with the smooth straws according to example 1, the ridged straws according to example 4, respectively and the aforementioned plastic straws. The results of this comparison test are summarized in the radar charts of Figures 1 and 2.

As it may be seen from said charts, the presence of ridges on the outer surface of the straws allowed, with both types of mineral water, to significantly reduce the perception of the starch/ flour note and the stickiness sensation to the lips. The ridged straw also generated less turbidity and fewer bubbles with respect to the smooth straw.

For the plastic straw, the tasters found a certain plastic taste, not reported for the pasta straws, and a bitter aftertaste and note comparable to those of the pasta straws. Appendix

Method for determining the content of extractable proteins.

The proteins of wheat gluten, namely monomeric gliadins and polymer glutenins, were extracted from the matrix and then separated according to the different solubility in alcohol. Each of the two extracted components was then quantified according to the technique described by J.B. Dumas (Dr. D. Julian McClements, “Analysis of Proteins”, University of Massachusetts Amherst Retrieved 2007-04-27). According to this technique, the sample is burned in a suitable high- temperature system in the presence of oxygen and a catalyst for the reduction of nitrogen oxides to molecular nitrogen. The gases produced are selectively removed by making them pass in helium flow in traps for residual oxygen, water and carbon dioxide. The nitrogen generated by the sample passes unaltered and reaches a thermal conductivity detector of the gas-chromatographic type.

By comparing the two ingredients semolina vs regrind pasta, it is found that the extractable protein content of the regrind pasta is significantly lower than that of durum wheat semolina; in fact, the regrind pasta has already undergone a strong heat treatment, and this makes proteins less available for extraction. For the regrind pasta and durum wheat semolina used as raw materials in the above reported examples 1-4, a content of extractable proteins equal to 79 g/ 100 g and 100 g/ 100 g of protein contained in the sample, respectively, was determined.