The present invention relates to a dry coating pre-mix for potato fries, to the coated potato fries, to the finish-fried potato fries and to the use of the pre -mix to prepare coated potato fries.

Methods for preparing and applying coatings to the outer surfaces of deep-frozen potato products are well known in the art. These methods and coatings are used for various purposes, such as improving the holding time for fast-food restaurants and home delivery, achieving the desired color of the final product, stabilize odor and taste and impart crispiness and crunchiness to the exterior of the product.

The potato fries market is changing. There is a growing popularity of online food delivery, which puts a higher demand on the holding time. The increasing awareness of healthier eating habits also has an impact. Potato fries with a lower fat content or suitable for alternative frying techniques are in higher demand. Furthermore, there is a trend towards better taste and mouth feel. More than half of the consumers are interested in trying new sensory experiences with crispiness and crunchiness as important attributes.

It is the object of the present invention to provide means that increase the crispiness and crunchiness of potato fries while maintaining a soft creamy interior and an acceptable holding time.

This object is achieved by means of a dry coating pre-mix for potato fries, comprising a coating base and a hydrocolloid that is capable of reacting with divalent ions, which coating premix when applied as a batter to potato fries confers a crispy and crunchy external texture and a large contrast inside/outside to the fries after finish-frying.

It was found according to the invention that the presence of such hydrocolloids, and in particular alginate and carrageenan in the coating lead to a crispier and crunchier sensation and a larger contrast inside/outside as compared to existing potato fries.

Alginates and carrageenans are hydrocolloids obtained from brown and red seaweeds. In the presence of divalent cations, mostly Ca ²⁺ , these ions can bind to the carboxyl groups in alginate and act as cross-linkers that stabilize the alginate chains by formation of a gel-network. Carrageenans are soluble in water, but the solubility inter alia depends on the presence of potential associated cations, such as sodium, potassium, calcium, and magnesium, which promote cationdependent aggregation between carrageenan helices leading to gel formation. Both types of molecules are thus capable of reacting with divalent ions, such as Ca ²⁺ and Mg ²⁺ .

When the hydrocolloid is alginate, the content thereof in the pre-mix is suitably 0.05 and 0.40%, in particular between 0.09 and 0.36%, more in particular between 0.12 and 0.25%, even more in particular between 0.15 and 0.20%. A content of 0.18% is most preferred. When the hydrocolloid is carrageenan, the content thereof in the pre-mix is between 0.20 and 1.5%, in particular between 0.25 and 1%, more in particular between 0.35 and 0.8%, even more in particular between 0.45 and 0.55%. A content of 0.5% is most preferred.

The coating base of the dry coating pre-mix comprises modified potato starch and rice flour. The coating base may further comprise other ingredients, in particular ingredients selected from potato maltodextrin, native potato starch, animal proteins, such as egg, vegetable proteins, in particular pea protein, potato protein, soy protein, rice protein, corn protein, legume protein, such as bean protein, chickpea protein, lentil protein, salt, sodium acid pyrophosphate (SAPP), sodium bicarbonate, dextrose, xanthan gum or combinations thereof. Rice flour and native potato starch are fillers. Rice flour also further adds to the crispiness. The other ingredients have functionalities that confer particular properties upon the coating. Modified potato starch is a film forming agent and contributes to the adhesion of the coating to the surface of the potato fries. Dextrose is added to obtain a golden brown, slightly glossy appearance. SAPP and sodium bicarbonate are leavening agents. Together they produce CO2 which becomes trapped in the coating and becomes fixed after finish frying. This further adds to the crispiness. Xanthan gum is a thickening agent that increases the viscosity of the coating thus facilitating application of the coating to the potato fries. Although some ingredients from the coating base may also contribute to the crispiness and crunchiness of the potato fries coated with the coating of the invention, the hydrocolloid significantly improves the crispiness and crunchiness obtained with the coating base alone.

The invention further relates to a batter for coating potato fries, comprising the dry coating pre-mix described above and a liquid. The liquid is suitably water. The ratio between dry coating pre-mix and liquid is 1:2, preferably 1:1.75, more preferably 1:1.5.

In the pre-coating pre-mix the hydrocolloid, in particular the alginate, is in solid form. In an alternative embodiment, the hydrocolloid, in particular alginate, may be in a liquid form. In the case, the hydrocolloid solution is added after preparation of the batter from a dry coating pre-mix without the hydrocolloid. An alginate solution can for example be stirred into the batter in a tank.

The invention further relates to potato fries coated with a batter prepared from the dry coating pre-mix. The batter is applied to the potato fries by dipping freshly cut and optionally preheated potato strips in the batter and putting the strips on a grid to drain excess batter. After coating the strips are pre-fried.

The potato strips are for example pre-heated by means of blanching in hot water or with steam.

In one embodiment, the only pre-treatment is the pre-heating. In a further embodiment the pre-heated potato strips are exposed to a short dip in a solution with an acidulant, in particular SAPP. Thus, according to the invention, before being coated with the batter, the potato strips are preferably not exposed to any further chemical or enzymatic treatment composition.

In the potato fries industry, the fries are usually pre-fried. Pre-fried potato fries coated with a batter made of the dry coating pre -mix of the invention are thus also part of this invention. After pre-frying, the potato fries can be sold as fresh potato fries. For this, the pre-fried fries are cooled down to refrigeration temperature and transported to the wholesale, retail facility or foodservice industry, such as catering services, restaurants, pubs and the like. Alternatively, the fries are conserved to preserve chemical, microbiological and sensory quality until the moment of final preparation and consumption. In one embodiment, the potato fries are cooled down and deep- frozen for longer storage.

Before consumption , the coated fries, pre-fried fries or deep-frozen fries must be finish- fried. Finish-frying comprises cooking coated potato fries of the invention for 2 to 5 minutes at 160 to 190°C in oil. Finish-fried potato fries, obtainable by finish- frying coated potato fries of the invention are also part thereof.

Instead of cooking the potato fries in oil, they can be finish-fried in an air fryer or oven.

As a result of the coating, the finish-fried potato fries of the invention perform better than existing crispy and crunchy potato fries with respect to crispiness and crunchiness. The finish-fried potato fries of the invention also have a larger contrast inside/outside.

The crispiness and crunchiness and contrast inside/outside of the potato fries that have been coated according to the invention are determined by means of a sensory test panel. Sensory analysis is a commonly used method to evaluate the texture of foods. In determining the parameters used to define the potato fries coated according to the invention Quantitative Descriptive Analysis (QDA) (Stone, H., Sidel, J., Oliver, S., Woolsey, A., and Singleton, R. C., (1974). Sensory evaluation by quantitative descriptive analysis. Food Technol. 28(11), 24, 26, 28, 29, 32, 34) is used. This is a behavioral sensory evaluation approach that uses descriptive panels to measure a product’s sensory characteristics. Panel members use their senses to identify perceived similarities and differences in products. They use a vocabulary which is agreed upon between the panelists. Line scales are employed for panel training and data collection. During the test, panelists place a cross on the line scale. The position of this cross is translated into an exact score between 0 and 100. The scale direction goes from left to right with increasing intensities, e.g., ‘not’ or ‘no’(score of 0) to ‘very’ or ‘large’ on the right side of the scale (score of 10). The difference among products is a value without dimension.

Employing this technique, the finish-fried coated potato fries of the invention, when served after 5 minutes holding time at room temperature after finish-frying, have a crispiness of at least 60 on a line scale of 0 to 100 as determined by a sensory panel after taking a bite with the incisors. The crispiness is preferably at least 65, more preferably at least 70, even more preferably at least 75 or at least 80, most preferably at least 85 on the above-mentioned scale.

When determining the crunchiness with the same technique, the finish-fried potato fries of the invention, when served after 5 minutes holding time at room temperature after finish-frying, have a crunchiness of at least 60 on a line scale of 0 to 100 as determined by a sensory panel after chewing between the molars. The crunchiness is preferably at least 65, more preferably at least 70, even more preferably at least 75 or at least 80, most preferably at least 85 on the above-mentioned scale.

The finish-fried potato fries of the invention, when served after 5 minutes holding time at room temperature after finish-frying, have a contrast inside/outside of at least 60 on a line scale of 0 to 100 as determined by a sensory panel after placing the centerpiece of the fry between the molars and biting down through the product. The contrast inside/outside is preferably at least 65, more preferably at least 70, even more preferably at least 75, most preferably at least 80 on the above-mentioned scale.

The coating of the invention also provides a better holding time. The holding time is the time after which finish-fried potato fries lose their crispiness and crunchiness and turn cold. A long holding time is in particular important for delivered foods. The finish-fried coated potato fries of the invention, when served after 30 minutes holding time in a quick-service restaurant cup in two paper bags placed in a delivery bag of a food delivery platform, have a crispiness of at least 60 on a line scale of 0 to 100 as determined by a sensory panel after taking a bite with the incisors.

The potato fries, when served after 30 minutes holding time in a quick-service restaurant cup in two paper bags placed in a delivery bag of a food delivery platform, have a crunchiness of at least 60 on a line scale of 0 to 100 as determined by a sensory panel after chewing between the molars.

The finish-fried potato fries, when served after 5 minutes holding time at room temperature after finish- frying, have a contrast inside/outside of at least 60 on a line scale of 0 to 100 as determined by a sensory panel after placing the centerpiece of the fry between the molars and biting down through the product.

It should be noted that the above-described values for crispiness and crunchiness and for contrast inside/outside are obtained when the sensory test is performed as described in Example 2. Other tests may lead to different results.

The invention further relates to the use of the dry coating pre -mix as described herein in the preparation of potato fries with a crispy and crunchy external texture and a large contrast inside/outside. The preparation of the potato fries comprises finish-frying the potato fries after applying a batter comprising the dry coating pre-mix. The invention also relates to a method for the preparation of potato fries with a crispy and crunchy external texture and a large contrast inside/outside, comprising a) coating potato strips with a batter; b) pre-frying the coated strips; c) optionally deep-freezing the pre-fried strips; and d) finish-frying the strips to obtain potato fries.

Before coating the potato strips may be pre-heated, for example by means of blanching. After prefrying the strips can be deep-frozen or stored in a refrigerator before finish-frying. Deep-frozen fries are suitably not thawed before finish-frying. Preferably, the method of the invention consists of steps a), b) and d) or of steps a), b), c) and d).

The step of finish-frying may be performed later in time than coating and pre-frying and optionally deep-freezing. In one embodiment, finish-frying is performed days to months after deepfreezing. In another embodiment, finish-frying is performed hours to weeks after pre-frying. In the latter embodiment, the pre-fried potato strips are refrigerated until finish-frying. The method of the invention encompasses the situations in which the fries are immediately finish-fried, are finish- fried after having been refrigerated for a period of time and are finish-fried after having been stored in deep-frozen state for a period pf time.

The present invention will be further elucidated in the Examples that follow and that are given for illustration purposes only and are not intended to limit the invention in any way.

EXAMPLES

EXAMPLE 1

Preparation of hydrocolloid-containing coating for potato fries

Introduction

This example describes the preparation of coatings with different hydrocolloids as the functional ingredient and testing of these coatings for crispiness and crunchiness and for contrast inside/outside.

Materials and methods

Batter

A coating base contains the ingredients listed in Table 1. This is also the pre-mix for the reference batter. Rice flour and native potato starch are the fillers. Part of these is replaced by the hydrocolloid to be tested. The remainder of the dry pre-mix is then constituted by the fillers in a ratio of about 2:1. The coating base without the fillers is called herein “backbone”. Table 1

* fillers

Table 2

Potato fries

To prepare the sample fries, the potatoes are washed with cold tap water and a scrub brush and subsequently pre-heated for 20 minutes in a bucket with tap water of 50-60°C. The potatoes are then cut into strips with a universal potato cutter to a cutting size of 9x9 mm. The potato strips thus obtained are transferred immediately to a bucket with cold tap water. The potato strips are blanched for 8 minutes in a water bath of 81°C.

Immediately after blanching, the potato strips are dipped for 30 seconds in a bath containing 0.5% SAPP (sodium acid pyrophosphate). Drying the potato strips is done in a Rational oven for 8 minutes at a temperature of 50°C and relative humidity of 0%. Only completely straight strips without convex sides are used. The coating batter is prepared by mixing 480 g dry pre-mix in 720 g cold tap water. The batter is first mixed with a whisk and subsequently with a KitchenAid Classic 5KSM45 mixer with a whisk at level 3. After 10 minutes rest the batter is mixed for another minute at level 3.

The potato strips are coated by putting a handful of strips in a bowl with the batter and removing the strips with a skimmer and placing them on a cake grid. Superfluous batter is blown from the strips with a hairdryer at the highest speed and cool setting from a distance of about 5 cm.

The coated strips are distributed over two frying baskets and pre-fried for 1 minute in sunflower oil in a frying pan that was pre-heated to 175°C.

The pre-fried fries are then put in the freezer on a rack covered with seal foil to be cooled down to room temperature. Then the fries are stored in a freezer at -20°C until use.

Before use in the different tests, the deep-frozen potato fries are fried in 200 g batches in sunflower oil of 175°C in a pre-heated frying pan for 2:45 minutes. Afterwards, they are cooled down for 2 minutes.

Organoleptic tasting

The finish-fried fries were tasted by two trained panelists. The results are shown in Table

3.

Table 3

Texture analysis

Crispiness was tested by means of an acoustic measurement with a Texture Analyzer (type TA.XT.plusC). The Texture Analyzer is placed in a sound-proof box together with a microphone (type TEDS GRAS.46AE no. 389179). A 45 mm long cylinder probe TA-520A with a diameter of 20 mm (type P/20P) was used to crush the fries. The noise caused is recorded by the microphone and measured by means of the Sound Software of the microphone. The Sound Software registers the number of events that a sound is recorded and the sound level of the crackling of the fries upon impact of the probe. The Force Software of the Texture Analyzer records the required force during contact of the probe and the sample fry (FO), the required force for breaking the sample (Fl) and the force at the end of the measurement (F2). The force and sound measurements were combined by means of AnalyseForceSound software, and the crispiness calculated. The results are shown in Figure 1 and Table 4.

The results are averages of 7 measurements. Initially, 10 measurements were made, and the outliers were not taken into account. The baseline measurement is a coating only comprising the coating base without the hydrocolloids and without the fillers. The reference is a factory sample, which is the fry with the coating base.

Table 4

EXAMPLE 2

Sensory tests

Introduction

Three separate descriptive sensory tests with the LWM Sensory Panel have been performed to understand how a 9x9mm skin off or skin on product comprising the coating of the invention performs compared to other comparable 9x9 coated fries.

For comparison, the commercially available McCain SureCrisp™ and Aviko SuperCrunch and potato fries coated with the coating base (called herein Reference 1) were used. All four tested products have in two tests also been tested after a holding time of 30 minutes. Materials and methods

The Quantitative Descriptive Analysis (QDA) method has been used for this test to describe the products. Before the start of the tests, the panelists agreed upon the vocabulary to be used. The sensory vocabulary used will be described below. All products were presented blindly at eating temperature to the panelists following an unbalanced block design.

All panelists are employees of Lamb Weston/Meijer v.o.f., who have been selected based on their ability to detect basic flavours and odours, their ability to verbally express themselves and their ability to learn new attributes. In addition, these panelists have been trained in the Lamb Weston/Meijer vocabulary for fries and different sensory testing methods.

Table 5 summarizes the parameters of the three tests.

Table 5

The samples were prepared by frying 680 grams of deep-frozen product for 3:15 min at 175°C in a 17 kW Henny Penny fryer. After cooking, the products for direct service were scooped into boat cups labelled with 3-digit codes. These products were served to the panelists after a holding time of 5 minutes at eating temperature.

The products with a holding time of 30 minutes were scooped into a QSR cup in a double layer white paper back in an Uber Eats delivery bag (Table 6).

Table 6

The panelists were seated in sensory booths with appropriate daylight lighting and a slight over-pressure to prevent contaminating odours to enter the booths. The products were served with 3-digit codes following semi-monadic presentation. To balance out the position of the products as equally as possible, an unbalanced block design has been used. With this, effects related to the order in which the products are presented to the panelists is minimized.

The data has been collected using EyeQuestion software (version 5.0.5.5). Each panelist had approximately 8 minutes to evaluate each product. Within this time frame they had to score the attributes on a line scale. The attributes relevant for the invention are crispiness and crunchiness and contrast inside/outside. The LWM vocabulary for these attributes is shown in Table 7.

Table 7 During the test, panelists place a cross on a line scale. The placing of this cross is translated into an exact score between 0 and 100. The panelists had no possibility to look back at the scores of previous products. Their judgement was therefore based on their internal reference framework and the memory of the previous products.

The data analysis was carried out using EyeOpenR software (version 5.0.5.5). For every attribute an ANOVA has been performed, in which panelists and products were taken into account as fixed factors. When a significant difference between the products was found, a post-hoc analysis following the Tukey method was performed on the data to gain insight into the nature of the differences. This analysis was performed at a 95% confidence level.

Results

The results of the various experiments are summarized in Tables 8a, 8b and 8c. Table 8a

Crispiness

Table 8b

Crunchiness Table 8c

Contrast inside/outside

Note: Different letters in the columns for each attribute indicate a significant difference at p < 0.05. Products with the same letters are not significantly different at a 95% confidence level.

N.a.: not available

From the above Table 8 it follows that the products of the invention (1.1, 1.2 and 1.3) have by far the most crispy and crunchy external texture of all four tested products. The external texture of the products of the invention is still crispy and crunchy after 30 minutes holding time. The contrast inside/outside is also larger for the product of the invention. This effect is further illustrated in the spiderweb diagram of Fig. 2.