Abstract:The chemical, physico-chemical and functional properties of flour and starch from three varieties of jackfruit seed were analyzed in this study. Starch was isolated using distilled water, alkaline and α-amylase enzyme. All varieties of jackfruit seed flour had moisture content 6.28-9.16%, protein 9.19-11.34%, fat 1.18-1.40%, ash 1.53-2.66%, amylose 26.49%-30.21% and starch contents 81.05%-82.52%. Gala variety had highest amount of water soluble index, swelling water capacity and water absorption index than Khaja and Durasha varieties. On the other hand, isolated starch varied 8.39 to 12.20% moisture, 1.09 to 3.67% protein, 1.18 to 1.40% fat, 0.03 to 0.59% ash content. Starch isolated with distilled water had higher protein content, yield, amylose and total starch than starch isolated with alkaline and enzyme. However, purity was depended on the variety and extraction conditions. Enzymatic method gave highest amount of water absorption index and water soluble index as compared to distilled water and alkaline method. Results from this study suggest that jackfruit seed flour can be used as partial replacement of wheat flour and good source of starch.
Here, we investigate the effects of pH adjustment before heating milk on the textural properties of whey protein enriched yogurt. Whey protein enriched skim milk was adjusted to pH of 6.3, 6.7, and 7.1 followed by heating at 85 °C for 30 min. Yogurts prepared from milk heated at pH 6.7 showed remarkably higher G′ (storage modulus) values, water holding capacity and firmness compared to those prepared from unheated milk, or milk heated at pH 6.3 or 7.1. A relatively more compact protein network was observed in the yogurt made from milk heated at pH 6.7. Heating milk at pH 6.7 formed both whey protein‐associated casein micelles (WPA‐CM) and soluble whey protein/κ‐casein complexes (SWP‐CC), resulting in the presence of numerous aggregating particles, which was responsible for the firmer yogurt gel. Heating milk at pH 7.1 (mostly SWP‐CC) resulted in higher yogurt firmness than heating at pH 6.3 (mostly WPA‐CM).
Practical applications
Whey protein fortification and heating milk improve yogurt texture. However, different pH values of the milk before heating and whey protein fortification affect the properties of the yogurt. Variation of milk pH before heat treatment affects the degree of association between denatured whey proteins and casein micelles. As a result, inconsistencies occur in yogurt gel texture. This study showed that yogurt made from milk heated at pH 6.7 had increased firmness and water holding capacity compared with that when the milk was heated at pH 6.3 or 7.1. The pH of milk naturally changes slightly throughout the year, which in turn might affect yogurt firmness. Therefore, milk pH is an important parameter which needs to be adjusted to produce uniform quality yogurt to obtain a well‐accepted commercial product.
The aim of this study was to determine the degree of contamination caused by Cryptosporidium oocyts in regularly consumed salad vegetables sold at various wholesale and retail markets in northern part of Bangladesh. A total number of 165 samples of salad vegetables collected from different wholesale and retail markets were examined for detection of Cryptosporidium oocysts using sucrose flotation medium of 1.18 specific gravity and Ziehl Neelsen staining technique with some modifications. Cryptosporidium oocysts were detected in 47 (30%) of the total examined samples. About 40 Tomato, 35 Cucumber, 20 Lettuce, 35 Carrot and 35 Mint's leaf samples were examined while Lettuce had the highest (40%) contamination rate followed by Tomato (32.5%), Carrot (31.4%), Cucumber (25.7%), and Mint's leaf (22.8%). There was no significant difference (x2 = 2.278; p <0.05) among occurrences of Cryptosporidium oocysts in usually consumed salad vegetables sold at market. This study has shown that salad vegetables sold at wholesale and retail markets in northern part of Bangladesh are contaminated with Cryptosporidium oocysts, may pose a health risk to consumers of such products. This reveals food safety and significance of public health.
Onion bulbs were stored at five different temperatures to know the storage behavior of onion bulbs. Indian red onion bulbs were kept without wrapping at ambient conditions (25˚C ± 3˚C and 75% RH) and within polyethylene pouch at 2.5˚C, 6˚C, 7˚C and 13˚C for 60 days of storage period. Weight loss, total soluble solids (TSS), number of sprouted and rotten bulbs were measured at an interval of 10 days throughout storage. The greatest decrease (23.25%) in weight was observed throughout storage for onions stored at ambient conditions. TSS was observed to increase in all samples until 40 days of storage and then decreased up to 60 days. Lowest TSS (14.89 ˚Bx) was found in onion stored at ambient conditions at the end of storage. Maximum sprouted (67.25%) and rotten (17.78%) onions were observed for onions stored at 13˚C, whereas minimum sprouted and rotten onions were found at 2.5˚C at 60 days of storage. Results also recommend lowest temperatures (2.5˚C -6˚C) for prolong storage life of onion with no detrimental effects.
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