Palatability and Stability of Shortbread Made with Low Saturated Fat Content

Palatability and Stability of Shortbread Made with Low Saturated Fat Content High consumption of saturated fatty acids (SFA) is associated with increased risk of cardiovascular disease and the European Food Safety Agency has called for lower SFA intake. This study assessed the formulation of low SFA shortbreads by replacing 60% and 70% of the butter content with high oleic sunflower oil and water. The quality of the low SFA shortbreads was evaluated through acidity, peroxide value, moisture, ash content, water activity, pH, protein, fat content, and fatty acid profiles. A sensory evaluation was performed to ascertain the effect on flavor. Stability of the new formulations was assessed by conducting accelerated shelf-life studies. The high oleic sunflower oil replacement of butter at levels of 60% and 70% decreased the final SFA content by 52% and 61%, respectively. On the other hand, monounsaturated fat content increased 55% on average while polyunsaturated fat content increased by 40%. Furthermore the new formulations possess quality parameters similar to those of traditional shortbreads (TSs). The study of the shelf life of the products showed that there are no significant variations in peroxide values, malondialdehyde content, or fatty acid profiles in biscuits over time, confirming their high stability. The quantitative descriptive analysis showed that the TS and low SFA shortbreads have similar sensory profiles, and the consumer tests indicated that the low SFA shortbreads were well liked.

Abstract:

Keywords: fatty acids, food composition, food quality, omega-3 fatty acids, optimization

Consumers’ attention about obesity, diseases, and low fat foods is increasing. Therefore, one of the aims of the food industry is the production of fat-reduced products characterized by the same quality of the full-fat counterparts. Furthermore, the formulations of low saturated fatty acids shortbreads may be optimized by partially replacing butter with high oleic sunflower oil. This study of the shelf-life stability and the sensory profiles of low saturated fat shortbreads confirm that the new formulations possess quality parameters similar to those of traditional shortbreads.

Practical Application:

Introduction Biscuits are one of the most popular bakery products due to their great variety, convenience, and long shelf life (Rababah and others 2006; Caponio and others 2009). The main ingredients in biscuits are flour, sugar, fat, and water, and the quality of these ingredients can all affect the overall quality of the product. In particular, fat plays an important role in biscuits as it influences shelf life and contributes to the sensory experience (Zoulias and others 2002; Laguna and others 2012; Tarac´on and others 2013).

Shortbreads are biscuits characterized by being dense and brittle as their relatively high quantities of fat and sugar create a gluten network (Manohar and Rao 1999). The quality of the fat used in shortbread influences the flavor of the final product. Butter is commonly used for its flavor in shortbread recipes, but it is rich in saturated fatty acids (SFA) especially myristic, palmitic, and stearic acids (McKevith 2005). Even though fat is an important source of energy and facilitates the absorption of fat-soluble vitamins, high fat consumption is generally associated with obesity and subsequent health problems. In particular, high consumption of SFA and/or trans fatty acids (TFA) is associated with an increased risk for cardiovascular disease (Micha and Mozaffarian 2010). Recently, MS 20130994 Submitted 7/18/2013, Accepted 1/9/2014. Authors Marconi, Mangione, Falconi, Pepe, and Perretti are with Dept. of Agricultural, Food and Environmental Science, Univ. of Perugia, Via san Costanzo, 06126, Perugia, Italy.

Author Martini is with Colussi Group, Petrignano di Assisi, Perugia, Italy. Direct inquiries to author Marconi (E-mail: ombretta.marconi@unipg.it).

R

C 2014 Institute of Food Technologists

doi: 10.1111/1750-3841.12383 Further reproduction without permission is prohibited

the European Food Safety Agency (EFSA) published recommendations on the dietary reference values for fats including SFA, TFA, polyunsaturated fatty acids (PUFA), and monounsaturated fatty acids (MUFA; European Food Safety Agency 2010). In particular, the EFSA recommended that intakes of SFA and TFA should be as low as possible, however they did not suggest an upper limit for MUFA or PUFA intake. The EFSA also emphasized the relationship between dietary SFA intake and increased blood cholesterol/low density lipoprotein (LDL) concentrations; the replacement of SFA with MUFA and/or PUFA may help maintain normal blood LDL concentrations (European Food Safety Agency 2011).

Some previous studies have focused on improving sensory and nutritional profiles of biscuits (Maache-Rezzoug and others 1998; Chevallier and others 2000) with attention to proper diet. Additional studies have focused on developing low-fat biscuit recipes using emulsifiers, fat mimetics, and interesterified shortenings made from palm and cottonseed oils (Manohar and Rao 1999; Zoulias and others 2002; Dogan and others 2007; Handa and others 2010; Forker and others 2012; Tarac´on and others 2013).

One previous study (Regnicoli and others 2011) used 50% corn, soybean, and sunflower oils to replace SFA in shortbread and concluded that sunflower oil is a good SFA replacer because it had the best sensory profile.

Some vegetable oils (for example, sunflower, corn, and soybean) are rich in MUFA and PUFA. Oleic acid (OA) and palmitoleic acid are the most common MUFA found in nature. Among the polyunsaturated fats, the essential fatty acids linoleic acid (LA) and Vol. 79, Nr. 4, 2014 r Journal of Food Science C469

C: Food Chemistry

Ombretta Marconi, Roberto Martini, Andrea Mangione, Caterina Falconi, Carolina Pepe, and Giuseppe Perretti

Low saturated fatty acid shortbread . . .

Table 1–Shortbread recipes.

C: Food Chemistry

Ingredients (g)

TS

LSFS 60

Flour Sugar Butter Sunflower oil Yolk Albumin (NH4 )HCO3 NaHCO3 NaCl Water (mL)

300 140 100 0 24 37 1 1.5 1.25 25

325 140 40 51 24 37 1 1.5 1.25 34

TS: traditional shortbread.

LSFS 60: low saturated fatty acids shortbread (60% high oleic sunflower oil).

LSFS 70: low saturated fatty acids shortbread (70% high oleic sunflower oil).

Reagents. Sulfuric acid 96%, 0.1 N sulfuric acid solution (Fluka, Steinhem, Germany). Sodium hydroxide solution 40%, LSFS 70 sodium hydroxide solution 0.02 N, potassium sulfate anhydrous, 325 selenium, hydrogen peroxide 35%, petroleum ether, pumice 140 stone, potassium hydroxide, methanol, sodium sulfate anhydrous 30 (J. T. Baker, Deventer, Holland). 1,3-Diethyl-2-thiobarbituric 59.5 24 acid, butyl hydroxyl toluene, sodium dodecyl sulfate, ethyl ac37 etate, acetonitrile, boric acid solution 4% (Sigma Aldrich, St. 1 Louis, Mo., U.S.A.). Kjeldahl tablet and sodium chloride solu1.5 tion 2.5% (Carlo Erba, Milano, Italia). Hexane anhydrous (Panreac 1.25 Quimica, Barcelona, Spain). All reagents were of analytical grade 35.5 and the highest purity available.

linolenic acid (LNA) are of particular interest because of their requirement in the diet (McKevith 2005). Sunflower oil is characterized by a low content of SFA and high content of unsaturated fatty acids, mainly OA and LA (Preeti and others 2007). OA is the main fatty acid present in high oleic sunflower oil (Merrill and others 2008).

Studies have shown that diets rich in MUFA may play an important role in controlling cardiovascular risk factors such as hyperlipidemia by lowering levels of LDL cholesterol and raising high density lipoprotein cholesterol levels (Allman-Farinelli and others 2005; Micha and Mozaffarian 2010). Although OA and LA can have positive effects on health, they can also become oxidized in the presence of light, moisture, and high temperatures thereby imparting peroxides and off-flavors in food products (Merril and others 2008). In general, the more unsaturated a fat is, the more unstable and susceptible to oxidation and rancidity it is. Therefore, the short shelf life of high oleic sunflower oil and all vegetable oils restricts their use in food formulations.

The aim of the present study was to assess formulations of low saturated fat shortbreads made by partially replacing butter with 60% or 70% high oleic sunflower oil. The studies were conducted on both laboratory and pilot plant scales. Furthermore, accelerated shelf-life studies were conducted in order to evaluate the stability of the new formulations through peroxide values, fatty acid profiles, and malondialdehyde (MDA) content, a key product of lipid oxidation (Ray and Husain 2002). MDA has been used as a marker of oxidative damage in both biological samples (Kinter 1995) and foods (St. Angelo 1996), but few studies have focused on lipid oxidation in bakery products (Sakai and Kawahara 2005).

Sensory evaluation of the new formulations was also performed in order to ascertain the effects on the flavor of the low saturated fat shortbreads.

Materials and Methods Materials Biscuit ingredients. Wheat flour (Triticum aestivum L.) that was finely ground (“00,” with ash, protein, and moisture values of 0.55%, 11.00%, and 15%, respectively, and a strength of W = 146) was procured from Molini Popolari Riuniti di Ellera-Umbertide, Italy. The other shortbread ingredients were sucrose (Eridania, Bologna, Italy), butter (Grifolatte, Perugia, Italy), water, class A eggs (Ovito, Perugia, Italy), high oleic sunflower oil with 79.2% of cis-OA, 4.5% of palmitic acid, 3.6% of stearic, and 11.2% of LA (Oleificio Speroni, Fidenza, Italy), salt (Italkali, Palermo, Italy), sodium bicarbonate (E 500; Solvay, Milano, Italy), and ammonium bicarbonate (E 503; Bertolini, Brescia, Italy).

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Methods Biscuit preparation.

Laboratory scale. The quantities of ingredients used to produce traditional shortbread (TS) and the 2 levels of low saturated fatty acid shortbread (LSFS) are reported in Table 1. The replacement involved only the fat fraction of butter (85%).

The shortbread in this study was made by the “doughing up” method. In the first phase the butter and flour were mixed in a laboratory mixer (Kenwood Ltd., U.K.) for 5 min at 120 rpm and 25 °C. Meanwhile the sugar and the liquid ingredients (including the high oleic sunflower oil) were mixed separately in the mixer for 3 min at 150 rpm. In the second phase, the 2 mixtures were combined, baking powder ((NH4 )HCO3 and NaHCO3 ) was added, and the final dough was mixed for 5 min at 80 rpm. The dough was allowed to rest at 4 °C for 1 h after which it was manually sheeted and shaped into pieces of 40 mm in diameter × 5 mm in thickness. The biscuits were placed on a steel oven tray (length 33 cm × width 38 cm × height 3 cm × thickness 1 mm) and baked in a laboratory ventilated oven (Binder, N.Y., U.S.A.) at 180 °C for 15 min. The biscuits were packaged and stored in polypropylene bags after cooling.

Pilot plant scale. Once the LSFS recipe was optimized on the laboratory scale it was transferred to a pilot scale plant equipped with a vertical mixer IL30 Model (Dominici, Italy), a rotary press T280 Model (Padovani, Italy) and a static oven C/2B Model (TMP, Italy).

Biscuit evaluation. Moisture, pH, total nitrogen, protein, and ash contents were determined according to their respective Association of Official Analytical Chemists methods (Official Methods of Analysis 1980). The water activity (aw ) was determined using an AquaLab series 3 (Decagon, Pullman, Wash., U.S.A.) calibrated with lithium chloride solution (aw = 0.250 ± 0.003).

Determination of the acidity was conducted following the method of Tateo (1969). Briefly, 4 g of ground biscuit and 100 mL of an aqueous solution of neutral 50% ethanol were stirred for 15 min at room temperature. After filtration, 50 mLof the solution was titrated with NaOH 0.02 N using phenolphthalein as the indicator. The peroxide values of the oil samples were determined according to the European Official Methods of Analysis (European Community 1991).

The total fat content was determined according to the AOCS method (American Oil Chemist’s Society 1984). Lipid extraction was carried out by a Soxhlet extractor using petroleum ether as solvent for 6 h. The solvent was removed by vacuum evaporation. The fat content of the sample was expressed as a percentage of dry matter. The fat extract was used for the determination of fatty acid profiles by gas chromatography. The lipid extracts were trans-esterified by treatment with methanol/KOH solution,

Low saturated fatty acid shortbread . . .

Descriptor Color Hardness Oiliness Sweetness Saltiness

Definition Burned, undercooked, or well-cooked By steadily compressing the biscuit between the molars, the force required for compression.

By gently rubbing both sides of the biscuit with fingers, the greasy/oily sensation.

Fundamental taste sensation associated with sugars, perceptible on the tip of the tongue.

Taste of salt perceptible on the tip of the tongue and on the sides around it.

and the resulting fatty acid methyl esters were injected into the HRGC-FID system. The fatty acids were identified by comparing their retention times with those of commercial standards (Sigma Aldrich; Bravi and others 2009).

The MDA content of the biscuits was determined according to the method of Sakai and Kawahara (2005) using HPLC coupled with Flourimetric Detector DETBA-MDA adducts. The accelerated shelf-life test (ASLT), where storing the shortbreads for 1 d at 55 °C corresponds to 18 d at room temperature (20 °C), was performed in order to evaluate the shelf life of the biscuits (Robertson 1993). The shortbreads were kept in an oven at 55 °C for 5, 10, and 20 d corresponding, respectively, to 90 (T5 ), 180 (T10 ), and 360 (T20 ) days at room temperature and then subjected to chemical and sensorial analysis.

Sensory evaluation. Sensory evaluation was conducted to evaluate the palatability of the cookies and to evaluate whether there was a statistically significant difference between the TS and LSFS at T0 and T20 . In total 3 sensory tests were carried out: discrimination, quantitative descriptive analysis, and the hedonic test. For each test, panelists were presented with 2 biscuits in polyethylene bags, a glass of water to cleanse the palate, and the scorecard.

Quality parameter Acidity (g oleic ac./100 g product) Ash (%) PH Peroxide values (meq O2 /g) Moisture (%) aw Protein (%)

TS

LSFS 60

LSFS 70

0.75a

0.66a

0.76a 8.43a 26.25a 3.25a 0.260a 7.36a

0.80a 8.44a 23.96a 4.29b 0.310b 7.94b

0.65a 0.77a 8.41a 23.93a 4.40ab 0.340b 7.90b

Values with superscript letters, on the same row, that are different are significantly different (P < 0.05).

Mean reported of duplicate analyses from 3 technological replications.

TS: traditional shortbread.

LSFS 60: low saturated fatty acids shortbread (60% high oleic sunflower oil).

LSFS 70: low saturated fatty acids shortbread (70% high oleic sunflower oil).

Table 4–Fatty acid profiles of the shortbreads.

Total lipid (% of biscuit weight) Fatty acids (% of total fat content) Saturated fatty acids (SFA) Butyric (C4:0) Caproic (C6:0) Caprylic (C8:0) Capric (C10:0) Lauric (C12:0) Myristic (C14:0) Palmitic (C16:0) Stearic (C18:0) Behenic (C22:0) ࢣ SFA Monounsaturated fatty acids (MUFA) Palmitoleic (C16:1) Oleic (C18:1) ࢣ MUFA Polyunsaturated fatty acids (PUFA) t – Linoleic (C18:2) cis-Linoleic (C18:2) α-Linolenic (C18:3. n3) ࢣ PUFA

TS

LSFS 60

LSFS 70

18.60a

16.35b

17.58ab

2.13a 1.68a 1.13a 2.69a 3.26a 11.01a 31.08a 9.39a 0.06a 62.43a

0.95b 0.76b 0.48b 1.12b 1.31b 4.28b 15.10b 5.43b 0.50b 29.93b

0.72c 0.55c 0.35c 0.81c 0.95c 3.12c 12.42c 4.81c 0.57c 24.30c

1.79a 25.55a 27.34a

0.85b 57.67b 58.52b

0.69c 63.22c 63.91c

0.44a 4.70a 0.77a 5.91a

0.19b 8.74b 0.38b 9.31b

0.15c 9.41c 0.33b 9.89c

Discrimination test. The triangle-discriminating test was performed Values with superscript letters, on the same row, that are different are significantly by 30 untrained panelists of university students aging from 20 to different (P < 0.05). reported of duplicate analyses from 3 technological replications.

30 of which 19 were female and 13 were male. The panelists Mean TS: traditional shortbread. were self-reported traditional consumers of biscuits. Two tests were LSFS 60: low saturated fatty acids shortbread (60% high oleic sunflower oil). carried out, one comparing LSFS 60 (LSFS with 60% of high oleic LSFS 70: low saturated fatty acids shortbread (70% high oleic sunflower oil). sunflower oil) with TS and the other comparing LSFS 70 (LSFS with 70% of high oleic sunflower oil) with TS. Both tests were too hard; oiliness, sweetness, saltiness, and flavor: 0 = much too performed at T0 . weak, 1 = too weak, 2 = slightly weak, 3 = just about right, 4 = Quantitative descriptive analysis. A total of 6 trained panelists aged slightly strong, 5 = too strong, 6 = much too strong. Open-ended from 30 to 45 consisting 4 males and 2 females evaluated the comments relative to secondary descriptors identified by trained biscuits using the quantitative descriptive analysis technique. The panelists were also collected. panelists were trained in 10 sessions to identify and determine descriptors relating to smell, taste, and texture. The terms and Consumer sensory analysis. A total of 114 consumers (54 female and their corresponding definitions (Table 2) were available to the 60 male) aged from 19 to 59 y took part in the study to test the panelists during all sessions. The panelists belong to industrial acceptance of the LSFS70 at T0 . The consumer sample population bakery products and taste their products for the sensory analysis, was composed by students and employees of University of Perugia almost daily. The evaluation of the biscuits was carried out over 2 d and 52% of the participants reported frequent consumption of this in 2 sessions in which the LSFS 70 and TS at T0 and LSFS 70 and type of biscuit.

Each consumer received a packet containing 2 pieces of LSFS TS at T20 were evaluated. One replication of each treatment was performed by each panelist. A 7-point intensity scale was used; and tested the samples for acceptability of appearance, texture, color: 0 = much too light, 1 = too light, 2 = slightly light, 3 = fleste, and overall acceptance, reported in Table 3. Overall acjust about right, 4 = slightly too dark, 5 = too dark, 6 = much too ceptance was reported using a 5-point hedonic scale (where 1 = dark; hardness: 0 = much too soft, 1 = too soft, 2 = slightly soft, dislike extremely, 2 = dislike moderately; 3 = neither like nor 3 = just about right, 4 = slightly hard, 5 = too hard, 6 = much dislike, 4 = like moderately, and 5 = like extremely).

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Table 2–Definitions of physical and flavor descriptors used in Table 3–Chemical quality parameters of the different shortthe quantitative descriptive analysis. breads.

Low saturated fatty acid shortbread . . .

C: Food Chemistry

Statistical analysis Statistical analyses were performed using the software STATISTICA 8.0 (StatSoft Inc., Tulsa, Okla., U.S.A.) on data collected from chemical and sensory evaluation of TS, LSFS 60, and LSFS 70 during ASLT. Each biscuit sample was produced in triplicate and all the chemical analyses were performed in duplicate; so, the data reported in tables are means of 6 values. Significant differences (P ࣘ 0.05) in the chemical parameters of TS, LSFS 60, and LSFS 70 after 0 d at 55 °C (T0 ) and their fatty acid profiles were discriminated using an unpaired Student’s t-tests, whereas a paired t-test was used to discern the fatty acid profiles of the LSFS 60 and LSFS 70 in ASLT. A paired t-test was used to discern significant differences of sensory evaluation tests. Values were considered significantly different at P < 0.05.

Table 5–Fatty acid profiles of the LSFS 60 in the shelf-life study.

Fatty acids (% of total fat)

T0

Saturated fatty acids (SFA) Butyric (C4:0) 0.95a Caproic (C6:0) 0.77a Caprylic (C8:0) 0.48a Capric (C10:0) 1.11a Lauric (C12:0) 1.31a Myristic (C14:0) 4.29a Palmitic (C16:0) 15.11a Stearic (C18:0) 5.44a Behenic (C22:0) 0.50a ࢣ SFA 29.95a Monounsaturated fatty acids (MUFA) Palmitoleic (C16:1) 0.84a Oleic (C18:1) 57.64a ࢣ MUFA 58.48a Polyunsaturated fatty acids (PUFA) Results and Discussion t-Linoleic (C18:2) 0.19a The present study tested the use of high oleic sunflower oil cis-Linoleic (C18:2) 8.76a as a replacement for 60% and 70% of the butter in shortbread. α-Linolenic (C18:3. n3) 0.38a The shortbreads were prepared following the recipes reported in ࢣ PUFA 9.33a

Table 1. The chemical properties of the LSFSs compared with the control (TS) are reported in Table 3. The LSFS showed higher moisture, aw and protein values compared with the TS. The high moisture value in the LSFS is likely to be related to the amount of water added to compensate for the butter replacement with vegetable oils as has been reported elsewhere (Forker and and others 2012). The higher protein content of LSFS is probably due to the greater use of flour during the kneading phase in order to facilitate the workability of the product. The aw value is important for biscuits because it affects crispness. In fact, knowledge of just a product’s moisture content does not give information about its hydration (Arimi and others 2010). Biscuits typically have an aw of about 0.25, and they will not be crisp if the aw is above 0.35 (Manley 2000). Therefore, the aw values of 0.310 and 0.340 of the LSFS 60 and 70 were acceptable considering the aw limit value for the crispness.

Water activity and moisture content do not solely influence rheological properties but also the microbiological and sensory (flavor) properties of foods. Foods with an aw < 0.60 are considered microbiologically stable, although some of their constituents may undergo chemical reactions. A value of aw < 0.20 has been shown to enhance lipid oxidization accompanied by pronounced alterations of sensory qualities during storage (Labuza and De-

T5

T10

T20

0.98a 0.75a 0.49a 1.14a 1.34a 4.35a 15.23a 5.45a 0.49a 30.22a

0.98a 0.75a 0.49a 1.13a 1.33a 4.31a 15.16a 5.38a 0.57a 30.13a

0.93a 0.71a 0.46a 1.06b 1.24b 4.13a 14.87a 5.84b 0.51a 29.75a

0.84a 57.67a 58.51a

0.86a 57.73a 58.59a

0.81a 58.33a 59.14a

0.19a 8.73ab 0.38a 9.30a

0.19a 8.61b 0.37a 9.17b

0.19a 8.44 c 0.35b 8.98c

Mean reported of duplicate analyses from 3 technological replications.

T0 = 0 d; T5 = 90 d; T10 = 180 d; T20 = 360 d.

Values with superscript letters, on the same row, that are different are significantly different (P < 0.05).

ˇ gun 1971; Reed and others 2002; Cervenka and others 2006).

Thus, the aw values of our LSFSs which contain a high content of unsaturated fatty acids known to readily oxidize, are acceptable.

Total lipid content and fatty acid profiles of the shortbreads at T0 are reported in Table 4. The lipid contents of the LSFS 60 and 70 were lower than that of the TS. The fatty acid profiles were also different between the groups. Among the SFA, palmitic acid was the most abundant in all the samples that is mainly due to the butter concentrations. OA was the most prevalent unsaturated fatty acid followed by LA. Total SFA content was significantly decreased in the LSFS 60 and LSFS 70. Substituting high oleic sunflower oil for the butter reduced SFA content by about 52% in LSFS 60 and 61% in LSFS 70. On the other hand, there was a significant increase in MUFA content by 53% and 57% for LSFS 60 and LSFS 70, respectively.

PUFA content was increased by about 40% in both LSFS prototypes. The increases were the highest in OA and LA; this is due to their relative abundance in high oleic sunflower oil. These results

Figure 1–Peroxide values of LSFS 60 and LSFS 70 during the accelerated aging tests.

Number of replications: 3 LSFS 60: low saturated fatty acids shortbread (60% high oleic sunflower oil) LSFS 70: low saturated fatty acids shortbread (70% high oleic sunflower oil) T0 : 0 d; T5 : 90 d; T10 : 180 d; T20 : 360 d.

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Table 6–Fatty acid profiles of the LSFS 70 in the shelf-life study.

Fatty acids (% of total fat) Saturated fatty acids (SFA) Butyric acid (C4:0) Caproic (C6:0) Caprylic (C8:0) Capric (C10:0) Lauric acid (C12:0) Myristic acid (C14:0) Palmitic (C16:0) Stearic (C18:0) Behenic (C22:0) ࢣ SFA Monounsaturated fatty acids (MUFA) Palmitoleic (C16:1) Oleic (C18:1) ࢣ MUFA Polyunsaturated fatty acids (PUFA) t-Linoleic (C18:2) cis-Linoleic (C18:2) α-Linolenic (C18:3. n3) ࢣ PUFA

T0

T5

T10

T20

0.73a 0.5a 0.35a 0.81a 0.96a 3.13a 12.40a 4.80a 0.57a 24.25a

0.68ab 0.54a 0.35a 0.83a 0.99b 3.23a 12.60b 4.79a 0.56a 24.57b

0.65b 0.53a 0.35a 0.83a 0.99b 3.20a 12.55b 4.80a 0.57a 24.47c

0.55c 0.45b 0.29b 0.67b 0.78c 2.64b 11.22c 4.80a 0.62b 22.02d

0.69a 63.34a 64.03a

0.68ab 62.99a 63.67b

0.68ab 63.09a 63.77b

0.62b 66.14b 66.76c

0.15a 9.31a 0.32a 9.78a

0.14a 9.39a 0.32a 9.85a

0.14a 9.41a 0.33a 9.88a

0.12b 9.12b 0.27b 9.51b

Mean reported of duplicate analyses from 3 technological replications.

T0 = 0 d; T5 = 90 d; T10 = 180 d; T20 = 360 d.

Values with different superscript letters within the same row are significantly different (P < 0.05).

suggest that high oleic sunflower oil can be used to replace butter in shortbread dough to obtain LSFS. Alteration of the shortbread recipe can affect the workability of the dough. In fact, the dough substituted with high oleic sunflower oil was more oily and adhesive than the traditional dough (Baltsavias and others 1999). The workability was increased by adding a significant amount of flour during kneading and storing at a cool temperature before lamination. This suggests the water content should be reduced when the recipe is scaled up.

Temperature is one of the main factors influencing lipid oxidation that leads to the formation of off-flavor compounds that are unpalatable to the consumer (Calligaris and others 2007). Therefore, the LSFS were tested in an accelerated shelf-life test during which fatty acid profiles were monitored. MDA content was also performed to assess if MDA can be used as a marker for oxidative damage in shortbread (Bergamo and others 1998).

Figure 1 shows the changes in peroxide values of the LSFS 60 and the LSFS 70 stored at 55 °C during the accelerated shelf-life test. Peroxide values increased during storage, as expected (Calligaris and others 2007). At baseline (T0 ) the 2 samples showed equivalent peroxide values, which increased at T5 (which corresponds to 90 d at room temperature) and then it remained constant until T20 (corresponding to 360 d at room temperature). At T5 , T10 , and T20 the peroxide values of LSFS 70 were higher than LSFS 60, as expected given the higher content of unsaturated fatty acids. The fatty acid profiles of the 2 shortbreads did not vary during the test as reported in Tables 5 and 6. These tables show that, during the ASLT of the LSFS 60, most of the fatty acids did not change significantly (P < 0.05). A nonsignificant decrease in lauric (C12:0), capric (C10:0), t-linoleic (C18:2), and α-LNAs (C18:3, n3) was observed at T20 . On the other hand, a nonsignificant increase in stearic acid (C18:0) was observed at T20 . Similarly, LSFS 70 also showed nonsignificant decreases in all fatty acids except for stearic acid (C18:0) at T20 .

Figure 2 shows the changes in MDA content in the shortbreads during the ASLT. The results showed no significant variations in the amount of MDA during the storage time. While not significant, the higher MDA values at T20 in the LSFS 70 correspond as expected to their higher peroxide value. Taken together the peroxide values, fatty acid profiles and the MDA contents suggest the partial replacement of butter with high oleic sunflower oil at the current levels does not negatively influence the chemical stability of shortbread.

Two discriminating tests were performed to compare the shortbreads. Panel members were asked to identify the correct identities of the TS compared with the substituted biscuits. The tests showed that the LSFS 60 and LSFS 70 were perceived equal to the TS; only 13 panelists correctly discriminated between TS and LSFS 60, and only 7 between LSFS 70 and TS. Given that the sample of 33 panel members had a fixed α = 0.05, 17 positive responses were required to conclude that the samples are perceptibly different.

Therefore, the replacement of butter with high oleic sunflower oil did not introduce a sensorial difference in this study.

After observing that the new formulations lowered SFA content while maintaining quality and storage parameters similar to those of TS, we decided to transfer the recipe to a pilot scale.

The LSFS produced at the pilot plant was subjected to the ASLT and sensory evaluation to compare the LSFS 70 with the

Figure 2–MDA content in the LSFS 60 and LSFS 70 during the accelerated aging tests.

Number of replications: 3 LSFS 60: low saturated fatty acids shortbread (60% high oleic sunflower oil) LSFS 70: low saturated fatty acids shortbread (70% high oleic sunflower oil) T0 : 0 d; T5 : 90 d; T10 : 180 d; T20 : 360 d.

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Low saturated fatty acid shortbread . . .

Low saturated fatty acid shortbread . . .

Table 7–Sensory evaluation scores of TS and LSFS 70 at T0 and T20 .

ColorA HardnessB OilinessC SweetnessC SaltinessC FlavorC

C: Food Chemistry

TS T0 LSFS 70 T0 TS T20 LSFS 70 T20

2.95a 3.40b 2.57c 2.72c

2.43a 3.33b 2.95c 3.85d

2.68a 3.12a 2.92c 2.93c

2.88a 3.23a 3.45c 3.37c

2.33a 1.93a 2.78c 2.27c

3.45a 1.85b 3.23c 2.63d

n = 6; T0 = 0 d; T20 = 360 d.

Pairs (TS T0 compared with LSFS 70 T0 and TS T20 compared with LSFS 70 T20 ), with the different letters within the same column are significantly different (P < 0.05).

TS: traditional shortbread.

LSFS 60: low saturated fatty acids shortbread (60% high oleic sunflower oil).

LSFS 70: low saturated fatty acids shortbread (70% high oleic sunflower oil).

A Color: 0 = much too light, 1 = too light, 2 = slightly light, 3 = just about right, 4 = slightly too dark, 5 = too dark, 6 = much too dark.

B Hardness: 0 = much too soft, 1 = too soft, 2 = slightly soft, 3 = just about right, 4 = slightly hard, 5 = too hard, 6 = much too hard.

C Oiliness, sweetness, saltiness and flavor: 0 = much too weak, 1 = too weak, 2 = slightly weak, 3 = just about right, 4 = slightly strong, 5 = too strong, 6 = much too strong.

Table 8–Consumer evaluation scores for LSFS 70 at T0 .

Appearancea

Texturea

Flavora

Overall Acceptancea

3.82 ± 0.70

3.89 ± 0.83

3.67 ± 0.63

3.95 ± 0.58

LSFS 70 at T0

Values are presented as means ± standard deviations.

LSFS 70: low saturated fatty acids shortbread (70% high oleic sunflower oil). T0: 0 d. a Appearance, texture, flavor, overall acceptance: 1 = dislike extremely, 2 = dislike moderately, 3 = neither like nor dislike, 4 = like moderately, and 5 = like extremely.

TS at T0 and T20 . Table 7 shows the results of the quantitative descriptive analysis for LSFS 70 compared with TS at T0 . Student’s t-tests indicated that the LSFS 70 was significantly different from TS (P < 0.05) with respect to color, hardness, and flavor, however they were not significantly different in terms of oiliness, sweetness, and saltiness. At the end of the accelerated shelf-life test, T20 , the LSFS 70 was significantly different compared to TS in hardness and flavor. While both shortbreads showed normal chromatic decay at T20 , the LSFS 70 was reported by some panelists to exhibit a “fry” flavor. Other panelist comments described the butter flavor of TS more positively and pleasurable than the LSFS 70 flavor, but this result is acceptable for a new formulation and has been previously reported (Forker and others 2012; Taranc´on and others 2013). Our data indicate that 60% butter replacement with high oleic sunflower oil and water could be better for the flavor of shortbread. Regardless, the consumer sensory analysis of the LSFS 70 resulted in scores ranging from 3.67 to 3.95 for all descriptors, with an overall acceptance of 3.95 (Table 8). The results indicated that the LSFS 70 could be accepted by the consumers as a new formulation for shortbread biscuits.

Conclusions High oleic sunflower oil can be used to produce shortbreads with low levels of SFA, high levels of PUFA and MUFA, and good stability. The proposed formulations allow the use of the following claim to be included on the label per EFSA regulations: “low or reduced saturated fat (hard fat) or replacement of saturated fat with MUFA, PUFA (soft fat) low cholesterol.”

Another benefit is that because butter contains TFA, the use of high oleic sunflower oil to replace butter can also reduce TFA content in shortbread. One drawback of the oil substitution was that it produced a less consistent, more oily and adhesive dough than traditional dough, but this issue was resolved by adding a higher concentration of flour during kneading and storing at a C474 Journal of Food Science r Vol. 79, Nr. 4, 2014

cool temperature before lamination. The results of sensory analysis showed that the TS and the LSFS 70 have similar sensory profiles, and the consumer tests indicated that the LSFS 70 was palatable.

Acknowledgments We thank the Italian Ministry of Agricultural, Food and Forestry Policies for financial support of the project CERSUOM, and Dr. Valerio Colasante for his collaboration on the laboratory activity.

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