Abstract
In an attempt to achieve correct ratio of n-3 to n-6 fatty acids for health benefits, flaxseeds (Linum usitatissimum), a good source of n-3 fatty acids, were incorporated with optimized 20% replacement of peanuts in the formulation for the preparation of chikki. Tertiarybutylhydroquinone (TBHQ) at 200 ppm level used as an antioxidant. Results showed that there were no differences in texture or sensory quality among the samples with and without addition of antioxidant. The peroxide value of oil in chikki increased gradually at 37 °C on storage. At the end of 60 days at 37 °C, rancidity developed in samples without antioxidant but not in that with added antioxidant. Thus, TBHQ increased the shelf-life of the product. Addition of flaxseeds to chikki increased PUFA content, especially n-3 fatty acids, up to 9%, which were not present in chikki prepared only with peanuts. Thus the ratio of 18:2 to 18:3 increased with addition of flaxseed, which has significant health benefits.
Keywords: Chikki, Flaxseeds, Omega 3 fatty acids, Rancidity
Introduction
India with divergent food habits is having a number of traditional foods, including sweet products. Chikki is one of the popular Indian traditional sweet snack. Chikki is mainly prepared using jaggery as sweetener and roasted peanuts (Arachis hypogaea). Sweets or confections with jaggery are gaining popularity due to the awareness of its health benefits. Jaggery is obtained by concentrating sugar cane juice to solid or semi solid state. It is a natural sweetener having a sweet winy flavour (Shahi 1999) and contains protein, minerals and vitamins and is a potent source of iron and copper (Manay and Swamy 2001). There are several different varieties of chikki in addition to the most common peanut chikki. Usually ingredients such as puffed Bengal gram, sesame, puffed rice, beaten rice and copra (desiccated coconut) are used and some chikkis are made using a combination of these ingredients. Special chikkis are made out of cashew nuts, almonds and pistachio.
It has been reported that chikki prepared with added sodium bicarbonate were lighter, more yellow than other products (McKee et al. 2003). Process of making chikki with added soda was patented (Shelesky and Anderson 2000). Peanut chikki, peanut and sesame seed chikki and peanuts and spices mixed with Bengal gram meal were developed and evaluated for sensory and nutritional properties with regard to their use as nutritional supplements for school children (Chahal and Sehgal 1996). Since the product is popular among all sections of population in the country, an attempt was made to further enrich with nutraceuticals by incorporating flax seeds. Flax seed (Linum usitatissimum) is one of the richest sources of n-3 fatty acids, mainly consisting of alpha linolenic acid in addition to 18:2 (linoleic acid). Unlike fish oil, flaxseed provides one of the non-animal sources of n-3 making it ideal for vegetarians. Flax seed contains approximately 40% oil, 30% dietary fiber, 20% protein, 6% moisture and 4% ash (Oomah and Mazza 1998, Bathena Ali et al. 2003). In the present work flaxseeds were incorporated in chikki formulation to increase the essential fatty acids and the effect of incorporation of flax seeds on physico-chemical properties of chikki was studied.
Material and methods
Peanuts (Arachis hypogaea), linseed/flaxseeds (Linum usitatissimum) and jaggery were procured from local market. Peanut seeds were roasted to golden brown colour (120–130°C), dehusked, de-germed and crushed into small bits of about 2.8 mm. Flaxseeds were roasted at 120°C, coarsely ground in a domestic mixer, sieved through 850 micron mesh size to remove husk.
Preparation of chikki
Chikki control (A) was prepared by taking jaggery and peanuts in equal proportions. Jaggery was crushed and made into syrup with addition of water and warming and filtered through a nylon mesh of ~ 30 mesh to remove extraneous matter. The clear jaggery syrup was heated until the temperature reached 145 °C and immediately pre-weighed, roasted and dehusked peanuts were added and mixed thoroughly till the nuts get coated with jaggery syrup. Hot mass was then transferred on to a wooden board or clean platform, which was smeared with oil. The product was then spread uniformly by rolling it with the help of a roller. Vertical and horizontal lines were marked with a cutter to make individual slabs then cooled to room temperature (27 ± 2 °C) and were packed in polythene pouches.
Preparation of chikki with flaxseeds
Toasted and sieved flaxseeds were added at 20% level replacing peanuts in chikki formulation (B). Replacement of 20% was found to be optimum based on sensory evaluation and was chosen for further studies. The antioxidant TBHQ at 200 ppm (on the basis of total fat content) was added to formulation (B) and labeled as formulation (C).
Moisture estimation
Moisture was estimated by oven method (AOCS 1995).
Texture
The breaking strength or snap of chikki was measured using Universal Texture Measuring system (Model LR-5K, Lloyds, UK). The uniform size 7 × 3 × 1 cm of chikki was taken and 3-point bending/breaking test was performed using a load cell of 100 N with 6 replicates with a cross head speed of 50 mm/min. The force required to break the chikki into 2 pieces was recorded as the breaking strength (snap) and expressed in Newton (N).
Instrumental colour measurements
The colour was measured using CIELAB measuring system (model Lab scan, USA). Colour was determined using the 10°/D 65 setting and expressed according to Commission Internationale de L’Eclairaige (CIE) system and reported as L*, (lightness), a* (redness) and b* (yellowness) (Wiegand and Waloszek 2003). ΔE represents the total colour difference of the samples.
Fatty acid composition
The fatty acid composition of oil in chikki was determined by extracting the oil from Chikki with chloroform and converting into fatty acid methyl esters (FAME) using 14% boron triflouride/methanol as per AOCS (1995) method. The FAME were analyzed by GC-15A (M/s Shimadza Corporation Kyoto, Japan) equipped with flame ionization detector operating under the following conditions: Column, 2.4 m × 0.3 cm S-S packed with 15% DEGS; column temperature 180 °C. Injection temperature 220 °C, detector temperature 230 °C and carrier gas nitrogen at 15 ml/min. The peaks were identified by comparing retention time with those of authentic standards and represented as relative %.
Peroxide value
Oil from Chikki was extracted with chloroform, the solvent was removed under vacuum and peroxide value (PV) was determined as per AOCS (1995) procedure.
Sensory evaluation
The desirable characteristics of chikki were evaluated sensorily by a panel of 12 judges using a 10-point linear rating scale ranging from 0 (Lowest intensity on left) to 10 (Highest intensity on right end) (Amerine et al. 1965). The judges were asked to perceive the attributes such as colour, snap, hardness, crunchiness, chewiness, sweetness, peanut flavour, rancidity, off taste and overall quality and to mark on scale. Chikki samples with code number were served one at a time for evaluation. Sensory evaluation was carried out for freshly prepared Chikki products and those stored for 30 days at 37 ± 2 °C.
Storage studies
Chikki (100 g) were packed in 150 guage polypropylene pouches and kept at accelerated (37 °C) and at ambient (27 °C) temperatures. The stability of the products was evaluated by texture, peroxide value and sensory quality. Storage studies were carried out for 90 days.
Statistical analysis
All analyses were carried out in triplicate. Duncan’s Multiple Range Test was applied to differentiate among the means of different samples (p ≤ 0.05) (Harter 1960).
Results and discussion
Moisture
Moisture of chikki is very critical as it determines the quality and stability of the product. All the products had a moisture content of 2.4 to 3% (Fig. 1). No significant differences were observed between control chikki (A) and chikki with added flaxseeds (A and C) with respect to moisture. The moisture content of Chikki samples gradually increased in all the samples during storage. Crisp texture was observed up to 45 days under accelerated conditions and up to 60 days under ambient conditions, after which the Chikkis lost their crisp and crunchy texture. Moisture content of 5.5% rendered the product soft and at moisture content of >5.5%, Chikki became soggy and lost its characteristic crunchy texture.
Fig. 1.
Changes in moisture, texture and peroxide values of chikki during storage
Texture (Snap)
Chikki had a characteristic or desirable crunchy texture and was brittle on the first bite. The snap of Chikki, which ranged from 68.5 to 71.5 N initially decreased gradually during storage (Fig. 1). This could be due to the absorption of moisture in all the samples at ambient and accelerated conditions. Addition of flaxseeds did not affect the texture of Chikki.
Peroxide value
Adding flaxseeds to improve the PUFA content made the Chikki prone to rancidity, as revealed by higher PV compared to those of control as expected (Fig. 1). However, addition of antioxidant improved oxidative stability especially of Chikki with flaxseeds as shown by lower peroxide values (Fig. 1) both at ambient and accelerated conditions. Chikki with flaxseed and antioxidant (C) showed PV similar to those of control (A). Beyond 60 days of storage at accelerated conditions, a rancid odour was prominent due to higher PV.
Colour
The results (Table 1) showed that L*, which represents the lightness or brightness of the Chikki, decreased significantly with addition of flaxseeds, indicating that control samples were lighter in colour compared to others. Addition of 20% flaxseeds showed significant difference in a* and b* values compared to those of control Chikki.
Table 1.
Hunter color and fatty acid composition of fresh Chikki products
| A | B | C | |
|---|---|---|---|
| Hunter color | |||
| L* | 59.4 ± 2.62c | 49.1 ± 2.31b | 45.6 ± 2.18a |
| a* | 11.1 ± 2.18b | 9.3 ± 2.67a | 8.2 ± 2.01a |
| b* | 38.8 ± 1.83d | 28.8 ± 1.87b | 25.5 ± 2.13a |
| Δ E* | 52.0 ± 0.63a | 53.9 ± 0.93ab | 54.5 ± 1.13ab |
| Fatty acids,% | |||
| 16:0 | 14.0c | 11.9a | 13.9b |
| 18:0 | 4.2a | 4.5a | 5.8b |
| 18:1 | 44.6b | 41.7a | 40.7a |
| 18:2 | 29.2c | 27.8c | 26.0c |
| 18:3 | 0.7b | 8.85b | 9.2a |
| 22:0 | 3.1c | 3.0b | 2.6a |
| 24:0 | 1.3b | 1.4b | 0.9a |
Values in the same row with different superscripts differ significantly (p < 0.05)
A = Control chikki with 100% peanuts; B = chikki with 20% flax seeds; C = chikki with 20% flax seeds + antioxidant
Sensory quality of chikki with flaxseeds
Addition of flaxseeds showed an increase in the colour scores of the products (Table 2), which was also observed in the instrumental colour values (Table 1). Snap values showed no significant difference with increasing levels of flaxseeds. The hardness of the product decreased thereby increasing the chewiness of Chikki. Addition of flaxseeds did not show any significant difference in peanut flavor. Addition of antioxidant did not significant by affect the overall acceptability of Chikki.
Table 2.
Sensory quality of chikki with added flaxseeds stored for 30 days at 27 °C and 37 °C
| Sample | Colour | Snap | Hardness | Crunchy | Chewiness | Sweetness | Mouthfeel | Peanut flavour | Rancidity | Off-taste | OQ |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Initial | |||||||||||
| A | 5.2a | 7.5a | 7.7b | 6.7b | 4.1b | 6.0a | 7.6c | 7.3b | – | – | 8.8b |
| B | 7.4b | 7.4a | 6.9a | 6.3a | 5.3a | 6.3b | 6.4a | 5.8a | – | – | 7.1a |
| C | 7.5b | 7.5a | 7.0a | 6.4a | 5.3a | 6.1a | 6.8b | 6.3ab | – | – | 7.6a |
| At 27 °C, 30 days | |||||||||||
| A | 5.2a | 6.8a | 7.0b | 5.8b | 3.6b | 6.0a | 6.8c | 7.2b | 1.0a | – | 8.2b |
| B | 7.1b | 6.6a | 6.6a | 5.3a | 4.3a | 6.0b | 6.3a | 6.8a | 1.0a | – | 6.7a |
| C | 7.3b | 6.5a | 6.6a | 5.2a | 4.3a | 6.1a | 6.3b | 6.6ab | – | – | 6.9a |
| At 37 °C, 30 days | |||||||||||
| A | 5.0a | 7.0b | 7.0b | 6.6b | 4.0b | 6.0b | 6.0a | 7.0b | 2.0a | – | 8.0b |
| B | 7.0b | 6.7a | 6.3a | 5.3a | 6.2a | 6.3a | 6.4b | 6.2a | 3.0b | 2.5a | 6.0a |
| C | 6.2b | 6.8a | 6.5a | 5.5a | 6.5a | 6.4a | 6.2a | 6.1a | 1.0a | 4.2b | 6.3a |
A, B, C: As in Table 1. OQ: Overall quality (n = 12 panelists), 10 – Point linear scale
Values in the same row with different superscripts differ significantly (p < 0.05)
Sensory scores of all desirable attributes decreased slightly at both ambient and accelerated conditions at the end of 30 days when compared to the initial values (Table 2) but were still acceptable. Slight off taste and rancidity was evident in Chikki without added antioxidant at the end of 30 days of storage at accelerated temperature, compared to that with antioxidant thus increasing the shelf life of the product.
Fatty acid composition of Chikki with added flaxseed
n-3 fatty acids were present to the extent of about 9% in chikki with added flax seeds, whereas they were traces in the control Chikki prepared with peanuts alone (Table 1). No difference in fatty acid composition was observed on storage (data not shown). Thus the nutraceutical quality of Chikki was improved by increasing the n-3 fatty acid content with addition of flaxseeds.
Conclusion
Chikki, a popular sweet snack, was chosen as a vehicle for enrichment with nutraceuticals. Flaxseeds rich in n-3 fatty acids were added at 20% levels replacing peanuts in Chikki formulation. Addition of flaxseed did not show any differences on the textural qualities. Peroxide values increased on storage, addition of antioxidant was advantageous in increasing the shelf life of the product up to 90 days. There was an increase in PUFA content especially 18:3 in Chikki with addition of flax seed. Flaxseeds imparted a slight darkening to the product and the product was comparable in all quality attributes with control Chikki, containing only peanuts.
Acknowledgement
Authors thank Lokesh BR, Head of the department and Prakash V, Director of the Institute for their keen interest in the work.
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