Proximate Analysis of Garlic (Allium sativum) Paste Treated with Ascorbic and Citric Acids

Copyright: © 2016 Mutasim ZA, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract The prime objective of the study was to develop a preservation method for garlic paste that could prevent adverse quality changes, render the paste more shelf stable and possibly retain chemical characteristics of fresh garlic. Three separate batches of fresh garlic bulbs of two Sudanese varieties (Dongla and Berber) harvested in December 2011 were collected, peeled manually, separated into individual sound cloves, divided into 5 equal portions and crushed in a blender until a smooth puree was obtained. Before crushing, portions were assigned randomly to chemical treatments (T0 = no chemical additives (control); T1 = 0.5 mg/g Ascorbic acid; T2 = 2 mg/g Citric acid; T3 = 0.25 mg/g Ascorbic acid + 1 mg/g Citric acid and T4 = 0.5 mg/g Ascorbic acid + 2 mg/g Citric acid). The chemical additives (T0-T4) were added during bulb crushing. Each garlic treated portion was subdivided into 2 equal portions, packed in glass containers and hermetically closed, stored at 25°C or 40°C for 6 months and analyzed at an interval of 2 months. Proximate compositions were measured. The results indicated that storage temperature had a significant (p ≤ 0.05) effect on the chemical composition except the fat content. Storage at high temperature (40°C) elevated the chemical composition of the garlic paste except the ash content. Irrespective of variety, storage for 6 months elevated moisture, fat, fiber, and ash contents. Sensory evaluation was measured. The results indicated that garlic variety (Dongola and Berber) had a significant (p ≤ 0.05) effect on sensory evaluation of garlic paste. Storage at low temperature (25°C) elevated the sensory evaluation of garlic paste. Irrespective of variety, storage for 4 months elevated sensory evaluation except color. Organic acids (Ascorbic and citric acids) or their blends are recommended to produce a shelf stable garlic paste for up to 6 months at storage temperature of 25°C or less. Proximate Analysis of Garlic (Allium sativum) Paste Treated with Ascorbic and Citric Acids


Introduction
Garlic is a very important cash crop in Sudan particularly in the Northern states (Dongla and Berber), where there is a long winter season and light soil. It is also grown on a very limited scale in the Gezira, Darfur and Kordofan states. The total annual area under garlic in Sudan was estimated to be about 100 hectares and annual production about 16,000 MT with an average yield of 1,778 Kg/ha. Cardiovascular disease (CVD) is responsible for 30% of all deaths and 10% of DALYs (disability-adjusted life years) WHO [1]. In Sudan, the burden of cardiovascular disease is increasing rapidly and it is now a public health concern. It has a major socio-economic impact on individuals, families and societies in terms of healthcare costs, work absenteeism and national productivity [2]. The International Agency for Research on Cancer (IARC) reported that the incidence rates of oral cancer in Sudan are 3.7% for men and 2.6% for women IARC [3]. Garlic and garlic extracts are believed to possess beneficial effects for the prevention of cardiovascular diseases [4][5][6]. Studies have shown that garlic also provides protection to the cardiovascular system by inhibiting platelet aggregation, protecting blood vessels and lipoproteins from damaging effects of free radical oxidation, and reducing serum cholesterol levels by inhibiting cholesterol synthesis [7,8]. The garlic paste manufacturing process dates back 40 years and stems from the need to find a product with an industrial or semi-industrial process able to compete in the international market. Another advantage is that the surplus from the nonmarketable part of the harvest (broken-up bulbs, loose cloves, etc.) may be used for paste manufacture. The consumption of processed garlic products (e.g. chopped and fried) has considerably increased over the last few years, probably due to its ease of use, when comparing to fresh garlic [9]. The main objective of the present work was to select a method for processing of garlic paste to prevent changes that occur in fresh garlic, make the product shelf stable and retain chemical characteristics of garlic paste.

Preparation of garlic paste
Three separate batches of each fresh garlic bulbs of two Sudanese varieties (Dongla and Berber) were harvested in December 2011, collected, packed and transferred to the Department of Food science and Technology Laboratory, Faculty of Agric. University of Khartoum, Sudan. The garlic bulbs were peeled manually, separated into the individual sound cloves, cut in half and inner green shoots were removed. Prepared garlic cloves were divided into 5 equal portions and crushed by a blender until a smooth puree was obtained after 3 minutes. Before crushing, chemical additives were added during bulb crushing, no additive control (T 0 ), (Ascorbic acid 0.5 mg/g (T 1 ), 2 mg/g Citric acid (T 2 ), 0.25 mg/g Ascorbic acid +1 mg/g Citric acid (T 3 ), 0.5mg/g Ascorbic acid +2 mg/g Citric acid (T 4 ). Descriptive analysis was applied to select sensory attributes which best define the changes in color, texture and flavor when different concentrations additive

Sensory evaluation
The sensory analysis of garlic samples were carried out using a hedonic scale for acceptability. To determine the appropriate concentration of chemical additives. The samples were tested for color, flavor, texture and overall acceptance. the tests were carried out by an semi trained panel of 30 judges. The samples were evaluated at room temperature and under cool white fluorescent lighting. The panelists were asked to evaluate the descriptors, rating each sample on a 9-point hedonic scale.

Effect of garlic variety and storage temperature on proximate analysis of garlic paste
The interactive effect of garlic variety (Dongola and berber) and storage temperature (25°C and 40°C) on the moisture, protein, fat, and fiber contents of garlic paste are shown in Table 1. Results indicated storage temperature had a significant (p ≤ 0.05) difference in the amount of moisture content between varieties. Dongola variety had significantly (p ≤ 0.05) higher (63.15%) moisture content than Berber variety (62.72%). The moisture content of garlic was significantly (p ≤ 0.05) affected by the temperature to which garlic paste was stored. Garlic paste stored at 40 O C had the highest moisture content (63.58%) compared to that stored at 25°C (62.29%). The value obtained in this study was similar to the value obtained by Benkeblia, who reported that garlic contain 60-70% moisture content. Temperature had led to no significantly (p ≥ 0.05) difference in the protein content between varieties. Berber variety had higher (3.57%) protein content than Dongola variety (3.32%). The protein content of garlic was significantly (p ≤ 0.05) affected by the temperature in which garlic paste was stored. Garlic paste stored at 40°C had the highest (p ≤ 0.05) protein content (3.80%) compared to storage at 25°C (3.09%). The value obtained in this study is lower than that obtained by Blumenthal and Mark [10], who reported that garlic contain 5% protein. Treatments had no effect (p ≥ 0.05) on the fat content of the two varieties. Dongola and Berber varieties had (1.35%) and (1.32%) fat content respectively. The fat content of garlic was not significantly (p≥0.05) affected by the storage temperature. Garlic paste stored at 40°C had the highest fat content (1.41%) compared to that stored at 25°C (1.26%). The value obtained in this study was higher than that obtained by Blumenthal and Mark [10], who reported that garlic contain 0.15%, 0.68% and 0.60% fat content, respectively. Treatments had led to a significant (p ≤ 0.05) difference in the amount of crude fiber between the varieties. Dongola variety had significantly (p ≤ 0.05) higher crude fiber (4.20%) than Berber variety (4.12%). The crude fiber of garlic was not significantly (p ≥ 0.05) affected by the temperature at which garlic paste was stored. Garlic paste stored at 40°C or 25°C had the same crude fiber (4.16%) content. The value obtained in this study was higher than that obtained by USDA [11], who reported that garlic contain 2.10% crude fiber. The interactive effect of variety and temperature on the ash and carbohydrate contents of garlic paste is depicted in Table 2. Results indicated that Dongla and Berber had similar (p≥0.05) ash content. Dongola and Berber varieties had 3.96% and 3.92% ash content respectively. The ash content of garlic was significantly (p ≤ 0.05) affected by the temperature at which garlic paste was stored. Garlic paste stored at 25°C had the highest (p ≤ 0.05) ash content (4.06%) compared to that stored at 40°C (3.82%). The value obtained in this study was within the range set by Casado, et al. [12], who reported that, the ash content of garlic ranged between 2.65% and 8.40%.Treatments had led to a significant (p ≤ 0.05) difference in the amount of carbohydrates between varieties. Berber variety had significantly (p ≤ 0.05) higher carbohydrates (24.37%) than Dongola variety (24.03%). The carbohydrates of garlic was significantly (p ≤ 0.05) affected by the temperature at which garlic paste was stored. Garlic paste stored at 25°C had the highest carbohydrates (25.15%) compared to storage at 40°C (23.25%). The value obtained in this study was higher than the value obtained by Sowbhagya, et al., [13], who reported that garlic contain 21% carbohydrates.

Effect of chemical treatments and storage periods on proximate content of garlic paste
The interactive effect of chemical treatment (T 0 -T 4 ) and storage period (2-6 months) on the moisture, protein and fat contents are shown in Table 3. The chemical treatments had led to a significant (p ≤ 0.05) change in the moisture content of garlic paste. Irrespective of the chemical treatment the moisture content of garlic paste increased (p ≤ 0.05) with the increase of storage period. Likewise irrespective of the storage period untreated (control) garlic paste had the highest moisture content (p ≤ 0.05) among all treatments under test. While control garlic paste had the highest moisture content (63.88%), garlic paste treated with T 4 had the lowest one (61.81%). The value obtained in this study for the control garlic was similar to the value obtained by Benkeblia [14], who reported that garlic contain 60-70% moisture. The moisture content of the control garlic (irrespective of storage period) was comparable to the values (66.57%) reported by Odebunmi, et al.   [15,16] for the Nigerian garlic and to that (65%) reported by Blumenthal and Hark [10]. Also Topno, et al. [17] found that garlic paste contain 63.04% moisture. Storage period had led to a significant (p ≤ 0.05) difference in the protein content. Garlic paste stored for 2 months had significantly (p ≤ 0.05) higher (4.60%) protein content compared to that stored for 6 months (2.19%). The protein content of garlic was significantly (p ≤ 0.05) affected by the treatments to which garlic paste was subjected. Garlic paste treated with T 1 had the highest protein content (3.84%) compared to that treated with T 3 (3.17%).The value obtained in this study was lower than the value obtained by Banerjee, et al. [18], who reported that garlic contain 5% protein. Irrespective of storage period, control garlic paste had a protein content of 3.42% almost 1.7 times higher than that proposed by HSA guide. Also it is way, less than that reported for the Nigerian garlic (17.35% crude protein), according to Nwinuka et al. [19]. Spanish garlic had a protein content of 18.83% [20][21][22]. Discripancies in the findings of the different studies quoted here could be attributed to the fact that the latter investigators reported their protein content on dry weight basis while that of Banerjee, et al. [18] and the current study was on wet weight basis. Also varietal differences, geographical locations could account partially to the observed differences. Storage period had led to a significant (p ≤ 0.05) difference in the fat content. Garlic paste stored for 6 months had significantly (p ≤ 0.05) the highest fat content (2.03%) compared to that stored for 4months (1.50%). The fat content of garlic was significantly (p ≤ 0.05) affected by the chemical treatments to which garlic paste was subjected. Garlic paste treated with T 2 had higher fat content (1.47%) compared to that treated with T 4 (1.20%). The value obtained in this study for the control samples (1.619%) was higher than that obtained by Blumenthal and Mark [10], or that of Nwinuka, et al. [19] who reported that garlic contain 0.15% and 0.68% fat content respectively. The interactive effect of chemical treatment and storage period on the crude fiber, ash and carbohydrate contents are shown in Table 4. Up to 4 months of storage ascorbic acid treatments alone did not (p≥0.05) affect the crude fiber of garlic paste. Generally crude fiber content of  Values are mean ± SD. *Means in the same columns and rows bearing same superscript small letters are not significantly different (p ≥ 0.05) **Means in the same row with the same superscript capital letters are not significantly different (p ≤ 0.05). ***Means in the same column bearing different superscript capital letters are significantly different (p ≤ 0.01). T 0 = Control T 1 = Ascorbic acid (0.5 mg/g) T 2 = Citric acid (2 mg/g) T 3 = Ascorbic acid (0.25 mg/g) and Citric acid (1 mg/g) T 4 = Ascorbic acid (0.5 mg/g) and Citric acid (2 mg/g) garlic paste increased (p ≤ 0.05) with the increase of storage period. Garlic paste stored for 6 months had significantly (p ≤ 0.05) higher crude fiber (4.86%) than that stored for 2 months (3.52%). The crude fiber of garlic was significantly (p ≤ 0.05) affected by the treatments to which garlic paste was subjected. Garlic paste treated with T4 had significantly (p ≤ 0.05) higher crude fiber (4.37%) compared to the control (3.96%). The value obtained in the current study was higher than the value obtained by USDA (2004), who reported that garlic contain 2.10%, 0.73% and 1.5% crude fiber respectively. Chemical treatments had no clear trend on ash content. Garlic paste stored for 6 months had significantly (p ≤ 0.05) highest (5.18%) ash content compared to that stored for 2months (2.89%). The ash content of garlic was significantly (p ≤ 0.05) affected by the treatments to which garlic paste was subjected. Garlic paste treated with T 3 had significantly (p ≤ 0.05) higher (4.06%) ash content compared to the garlic treated with T 2 . The control (T 0 ) garlic paste had an ash content of 4.0%. The value obtained in this study is similar to the value obtained by Casado, et al. [12], who reported that, the ash content of garlic ranged between 2.65% and 8.40%. Also the ash content of the current study is similar to that obtained by Nwinuka, et al. [19] who stated that Nigerian garlic has an ash content of 4.01%. However another study for Nigerian garlic found that it contained 1.33% ash [16]. Treatments had led to a significant (p ≤ 0.05) difference in the amount of carbohydrates between chemical treatments. Garlic paste stored for 2months had significantly (p ≤ 0.05) the highest carbohydrates (26.80%) compared to that stored for 6months (20.94%). The carbohydrates of garlic was significantly (p ≤ 0.05) affected by the treatments to which garlic paste was subjected. Garlic paste treated with a T4 had significantly (p ≤ 0.05) high carbohydrates (25.64%) compared to that of T 0 (23.11%). The value obtained in this study was higher than that obtained by Sowbhagya, et al. [13], who reported that garlic contain 21% carbohydrates, but lower than that (28%) stated by HSA [21].

Effect of variety and storage temperature on the sensory evaluation of garlic paste
The effect of garlic variety (Dongola and berber) and storage temperature (25°C and 40°C) on the sensory evaluation of garlic paste is depicted in Table 5. Results indicated that storage temperature had led to a significant (p ≤ 0.05) difference in the color score. Dongola variety had significantly (p ≤ 0.05) higher color score (5.23) than Berber variety (4.09). The color score of garlic was significantly (p ≤ 0.05) affected by the storage temperature at which it was stored. Garlic paste stored at 25°C had the highest color score (5.29) compared to that stored at 40°C (4.53), indicating that low temperature storage preserved the color of garlic paste [22]. The variety had led to a significant (p ≤ 0.05) difference in the flavor score. Dongola variety had significantly (p ≤ 0.05) higher flavor score (2.30) than Berber variety (3.88). The flavor score of garlic was significantly (p ≤ 0.05) affected by the temperature at which garlic paste was stored. Garlic paste stored at 25°C had the Values are mean ± SD. *Means in the same columns and rows bearing same superscript small letters are not significantly different (p ≥ 0.05) **Means in the same row with the same superscript capital letters are not significantly different (p ≤ 0.05). ***Means in the same column bearing different superscript capital letters are significantly different (p ≤ 0.01). T 0 = Control T 1 = Ascorbic acid (0.5 mg/g) T 2 = Citric acid (2 mg/g) T 3 = Ascorbic acid (0.25 mg/g) and Citric acid (1 mg/g) T 4 = Ascorbic acid (0.5 mg/g) and Citric acid (2 mg/g) highest flavor score (4.72) compared to storage at 40°C (4.46). Storage temperature had led to a significant (p ≤ 0.05) difference in the texture score between varieties. Dongola variety had significantly (p ≤ 0.05) higher texture score (5.37) than Berber variety (5.20). The texture score of garlic was significantly (p ≤ 0.05) affected by the storage temperature to which garlic paste was stored. Garlic paste stored at 25°C had the highest texture score (4.87) compared to that storage at 40°C (4.70). Storage temperature had led to a significant (p ≤ 0.05) difference in the overall acceptability between varieties. Dongola variety had significantly (p ≤ 0.05) higher overall acceptability (5.50) than Berber variety (4.13). The overall acceptability of garlic was significantly (p ≤ 0.05) affected by the temperature at which garlic paste was stored. Garlic paste stored at 25°C had the highest overall acceptability (4.96) compared to that stored at 40°C (4.66).

Conclusion
Interactive effect of chemical treatment (T 0 -T 4 ) and storage period on the color, flavor and texture are shown in (Tables 6,7). Storage period had led to a significant (p ≤ 0.05) difference in the color score. Garlic sample stored for 2 months had significant (p ≤ 0.05) high color score (4.69) compared to that stored for 4months (4.63). The color score of garlic was significantly (p ≤ 0.05) affected by the treatments to which garlic paste was subjected. Garlic paste treated with T 2 had significantly (p ≤ 0.05) the highest color score (5.60) compared to that treated with T 4 (3.24). Treatments had led to a significant (p ≤ 0.05) difference in the flavor score among chemical treatments. Storage for 6 months had significantly (p ≤ 0.05) the lowest flavor score (4.57) compared to that stored for 2 months (4.62). The flavor score of garlic was significantly (p ≤ 0.05) affected by the treatments to which garlic paste was subjected. Garlic paste treated with T 3 had significantly (p ≤ 0.05) the high (5.34) flavor score compared to that treated with T 4 (3.37). Storage had led to a significant (p ≤ 0.05) difference in the texture score of the stored sample. Samples stored for 4 months had  T 0 =Control T 1 =Ascorbic acid (0.5 mg/g) T 2 =Citric acid (2 mg/g) T 3 =Ascorbic acid (0.25 mg/g) and Citric acid (1 mg/g) T 4 =Ascorbic acid (0.5 mg/g) and Citric acid (2 mg/g) Values are mean ± SD. *Means in the same columns and rows bearing same superscript small letters are not significantly different (P ≥ 0.05) **Means in the same row with the same superscript capital letters are not significantly different (P ≤ 0.05). ***Means in the same column bearing different superscript capital letters are significantly different (P ≤ 0.01). T 0 = Control T 1 = Ascorbic acid (0.5 mg/g) T 2 = Citric acid (2 mg/g) T 3 = Ascorbic acid (0.25 mg/g) and Citric acid (1 mg/g) T 4 = Ascorbic acid (0.5 mg/g) and Citric acid (2 mg/g) Table 7: Effect of chemical treatments and storage period on overall acceptability of garlic paste.
significantly (p ≤ 0.05) the highest texture score (4.87) compared to that stored for 6 months (4.71). The texture score of garlic was significantly (p ≤ 0.05) affected by the chemical treatments to which garlic paste was subjected. Garlic paste treated with T 2 had significantly (p ≤ 0.05) high texture score (5.40) compared to that treated with T 4 (3.68). Interactive effect of treatment and storage on the overall acceptability is shown in Table 3. Results indicated that treatments had led to a significant (p ≤ 0.05) difference in the overall acceptability among stored samples. Samples stored for 4 months had significantly (p ≤ 0.05) high overall acceptability (4.91) compared to that stored for 6 months (4.69). The overall acceptability of garlic was significantly (p ≤ 0.05) affected by the treatments to which garlic paste was subjected. Garlic paste treated with T 2 had significantly (p ≤ 0.05) high overall acceptability score (5.70) compared to that treated with T 4 (3.66).