Physico-chemical and Nutritional Assessment of Toffees Developed from Figs

Fig an ancient crop belongs to the mulberry family Moraceae. It is also known as ‘Anjir’ in Asia, ‘Fiege’ in German, ‘Figue’ in French and ‘Higo’ in Spanish Imran et al. (2011). Turkey is the world’s largest producer of figs with annual production of 274,535 Metric Tonnes followed by Egypt, Algeria, Morocco, Iran, Syrian Arab Republic, USA, Brazil, Albania and Tunisia (Anonymous, 2017). Few areas in India like Maharashtra, Gujarat, Uttar Pradesh, Karnataka, Punjab and Tamil Nadu cultivate fig as a minor fruit (Naikwadi et al., 2010) and “Poona Fig” is the most popular variety grown and consumed in fresh form (Marpudi et al., 2013). Fig is one of the most important medicinal fruits available worldwide and is often referred to as the ‘fitness fruit’. It consists of 84% pulp and 16% skin (Guvenc et al., 2009). 
       
Figs are a great source of minerals, vitamins, amino acids, crude fibres, carotenoids, antioxidants, phenolic compounds and various other compounds like arabinose, b-amyrins, glycosides etc (Soni et al., 2014). Besides being consumed in its fresh form, figs are also enjoyed as dried, canned in syrups and candied. In Europe, figs are used in preparation of coffee while wine and alcohol are produced from figs in the Mediterranean region (Naikwadi et al., 2010). Larger sized fruit could be consumed in fresh form whereas small sized fruit could be used for preparation of jams and marmalade (Gozlekci, 2011).
       
Toffee is one of the chewable confectionery products made from milk solids, sugar, vegetable oil or butter, artificial flavours and colours. Conventional toffees lack nutritional components and thus by incorporating a fruit pulp, a regular milk toffee can be transformed into a nutritionally rich processed product. Fruit toffee can be prepared either from a single fruit or combination of fruits. Various studies have prepared fruit toffees from nipa palm, aonla and papaya, strawberry and apple ber, guava and mango, cocoa-mulhati and guava (Supaking, 2019; Kumar et al., 2019; Deshmuskh and Thorat, 2018; Sucheta et al., 2018; Pawar et al., 2017).
       
There is a growing interest to consume figs owing to its high nutritional status but the major constraint is its perishability due to which its availability is only for a short period. Processed and convenient products like toffee will help in making it available round the year in a palatable form. The rich mineral content of the fig fruit will also help in combating anaemia in the target consumers. So, there is a dire need to develop this value-added convenience product to increase its consumption.
 

The research work related to the present study was carried out in the Department of Food Science and Technology, Punjab Agricultural University, Ludhiana during the year 2017-18. Fully matured and ripe fig fruit variety Brown Turkey was obtained from Department of Fruit Science, Punjab Agricultural University, Ludhiana. Chemicals of analytical grade were used in the investigation and other raw materials were procured from the local market.
 
Standardization of toffee recipe
 
Fig toffees were prepared by using six combinations of toffee blends by mixing fig pulp and other ingredients like butter, liquid glucose, sugar, milk powder, pectin, starch and water in different ratios such as 0:100, 10:90, 20:80, 30:70, 40:60, 50:50 (fig: other ingredients). Ripe fruits were washed and de-stemmed manually. Pulping was done by macerating fruit in a mixer until a uniform pulp was obtained. The flow diagram enumerating the steps in the preparation of fig toffee are given in Fig 1.


 
Chemical analysis of toffees
 
The toffees were chemically analysed for moisture, acidity, ascorbic acid, crude fat, crude protein, flavonoids, antioxidants, phenols, peroxide value and free fatty acids as per the standard (AOAC, 2000) and (AOCS,1997) methods.
 
Texture profile analysis
 
Texture measurements of fig toffee samples were performed using the texture analyzer (TA-Hdi), (Stable Micro systems, UK) were sample was compressed twice to 50% of the original height with a probe P/75 (Bhatt and Verma, 2016) with the load cell of 250 kg, pre-test speed 2.00 mm/s, Test speed 2.00 mm/s, post-test speed 5.00 mm/s, Distance 5.00 mm, Time 5.00 sec. From the resulting curve, hardness, cohesiveness, springiness, chewiness and gumminess were determined.
 
Sensory evaluation of toffees
 
Prepared fig toffee blends were evaluated by sensory evaluation to obtain the most acceptable and desirable toffee blend on the basis of appearance, colour, flavour, texture and overall acceptability by a panel of semi-trained judges (Larmond, 1970). The desirable blend obtained was checked for the sensorial attributes for three months with the interval of 30 days.
 
Statistical analysis
 
The data in the present investigation was subjected to analysis of variance (ANOVA) and thus analysed according to three factorial completely randomized designs.
 
 

Physico-chemical composition of toffees
 
Physico-chemical analysis of the toffee blends (Table 1) show that the blend with the highest percentage of fig content exhibited the highest nutritional content. Toffee blend containing no fig pulp was found to be containing higher amounts of total solids, fat, protein, free fatty acid and peroxide value. Low moisture content leads to high total solids content and high amounts of fat, protein, free fatty acids and peroxide value are due to the presence of 100% milk component. Other parameters like ascorbic acid, fiber, anthocyanins, carotenoids, antioxidants, phenols and flavonoids were found to be non- detectable in control due to absence of fig pulp.


 
Sensory analysis of toffee blends
 
Sensory analysis data from Table 2 shows that toffee blend containing 30% fig pulp scored highest for all the parameters and had an overall acceptability of 8.237 which was significantly higher than the control but had non-significant difference with all other blends. None of the blends were found to be undesirable as all of them got sensory rating of above 5 on a 9-point hedonic scale.


 
Nutritional composition of most desirable fig toffee (30:70)
 
Nutritional profile of fig toffee containing 30% fig pulp is summarized in Table 3. It can be seen that fig toffee contains appreciable amount of total solids (90.493%), total soluble solids (81°Brix), pH (5.967), titrable acidity (0.0087%), ascorbic acid (4.493 mg per 100g), crude fiber (2.890%), protein (3.973%), fat (9.877%) phenolic compounds (153.253 GAE mg per 100 g), antioxidants (60.6% inhibition activity per 100 g) and flavonoids (15.110 mg per 100 g) which provide numerous health benefits. Fig toffee is also a good source of various macro and micro minerals such as calcium (235.4 mg per g), Iron (2.945 mg per g), potassium (356.5 mg per g), magnesium (41.93 mg per g), sodium (157.1 mg per g), phosphorus (171.3 mg per g) and sulphur (105.0 mg per g) as given in Table 4. These minerals will help to meet the requirements of these micronutrients in diet which have established implications in various metabolic processes and health benefits.




 
Texture profile analysis (TPA) of fig toffee
 
Texture profile analysis of the desirable toffee blend that is containing 30% fig pulp was done using StableMicro System texture analyzer TAXT2i and the data was compared with the control that is milk toffee. From the curve data evaluated given in Table 5 and it can be seen that fig toffee has better textural properties that ordinary milk toffee.


 
Changes in chemical constituents of fig toffee during storage
 
Various changes during three months can be compared from Table 6 and it was found that pH of the fig toffees ranged from 5.967 to 5.660 which shows that fig toffee is a low acid food product. No significant change in pH was observed during the first month but it decreased significantly during the second and third month. In case of titrable acidity a significant decrease was noticed from 0.087% to 0.045%. The results were found to be in line with Pawar et al.,(2017), Divya et al.,(2014) and Nath et al.,(2005). Total solids decreased significantly from 90.493% to 90.423% and then the trend became non-significant as no change was seen throughout the storage period. The ascorbic acid content decreased significantly during the third month which might be due to light and heat sensitivity, as vitamin C gets lost during thermal processing as well as the oxidation of ascorbic acid to de-hydro ascorbic acid. Loss in ascorbic acid content in guava leather from 176-104 mg/g was observed by Jain and Nema (2007). Similar results have been reported by Divya et al., (2014) in sapota candy and Shakoor et al., (2015) in guava bar. Crude fibre content showed non-significant decrease because of thermal processing which significantly reduces the crude fiber content.


       
A significant decrease in the protein content from 3.973% to 3.037% was observed during storage. This decrease might be due to the maillard reaction where protein gets combined with sugar and leads to the formation of melanoidins (brown nitrogenous compound) (Anisa et al.,2016). Total carotenoids were found to decrease significantly with increasing storage period. This trend could be due to non-oxidative changes like isomerisation of trans-carotenoids to the cis-forms promoted by acids, heat treatment and exposure to light which reduces the color and the vitamin A activity of carotenoids; epoxide formation of thermal degradation or oxidative changes is stimulated by light, heat, some metals, enzymes and peroxides. Similar trend was observed in conformity with papaya toffee by Attri et al., (2014). Total flavanoid content was found to decrease significantly during storage. This might be due to oxidation of the compounds. Ramesova et al., (2012) reported that naturally occurring flavonoids like quercetin and luteolin when come in contact with atmospheric oxygen become unstable and gets degraded. Flavonoids are also pH and light sensitive and get degraded easily under sunlight and extreme pH conditions (Bohm, 1999).
       
The trend in antioxidant activity was found to decrease significantly from 60.6% to 40.8%. Similar trend was observed in phenolic compounds where a significant decrease was observed from 153.253 mg to 74.013 mg. The decrease in total phenols during storage might be due to their condensation into brown pigments. Similar observations were recorded by Waskar and Khurdiya (1987) in phalsa beverages. Kim and Zakour (2004) reported that this decrease may be due to destruction of anthocyanins (flavonoids), browning reactions and exposure to light. Zafrilla (2000) also determined the similar trend of decrease in total phenolics and antioxidants.
 
Effect of storage on sensory evaluation of fig toffee
 
From Table 7 it can be inferred that the sensory score for appearance of the product decreased significantly from 8.40 to 6.00 during three months of storage while colour scores decreased initially but no significant change was observed during the preceding months. This might be due to the temperature effect on the parameters as well as on surrounding atmosphere. The scores for flavour decreased significantly from 8.40 to 6.50 during three months storage. A gradual decrease in texture score from 8.10 to 6.20 was observed. This could be due to change in atmospheric conditions (difference in moisture content). Statistical analysis showed a significant decrease in overall acceptability scores of fig toffee. This was due to decreased scores for appearance, colour, flavour and texture. The overall acceptability scores decreased from 8.23 to 6.15. These findings were in accordance with Domale et al., (2008) for aonla pulp toffees, Sivakumar et al., (2007) for guava toffee and Ingle et al., (2016) for sugar free aonla candy.


 

Toffee blend containing 30% pulp was most acceptable than the other blends. Shelf-life studies for 3 months showed that prepared toffees could be stored well for 90 days at ambient temperature. Trend in the storage stability of the toffees with time could be checked further by carrying out the physico-chemical and organoleptic evaluation of the toffees at monthly intervals. Economics of the toffee revealed that price of fig toffee and milk toffee is approximately same but fig toffee has an advantage over other milk-based toffees that it is nutritionally enhanced and target consumer can derive health benefits like high antioxidant levels, high mineral content and all the necessary nutrients in the same price as that of milk-based toffee.
 

Laboratory facilities provided by Head, Department of Food Science and Technology, Punjab Agricultural University, Ludhiana, India to execute the present work are duly acknowledged.
 

This research did not receive any specific grants from funding agencies in the public, commercial or not-for-profit sectors.
 
 

 
None.