The peels of processed apples can be recovered for further food applications. Limited information on the valorisation of this type of waste is available for cooking varieties, e.g. cv Bramley’s Seedling. Extracts from fresh or dried (oven-dried or freeze-dried) peels were obtained with solvents of different polarity (aqueous acetone or ethanol) and assayed for their total phenolic content and antioxidant capacity; their antiradical power was compared to herb extracts. The dried peels were also characterised as bulk powders by assessing their nutritional value and total phenolic content. High amounts of ascorbic acid (up to 4 mg/g, dry weight) and polyphenols (up to 27 mg gallic acid equivalents/g, dry weight) were found in the peels, with the latter contributing significantly to the antioxidant capacity; the nutrient profile was low in protein (less than 10%, w/w) and total dietary fibre content (less than 40%, w/w). Higher yields of phenolic antioxidants were recovered with acetone from freeze-dried peels; the resulting extracts had equivalent antioxidant power to oregano leaves (Origanum vulgare L.). The combination of oven-drying/ethanol led to lower recovery yields of phenolic antioxidants; however, these conditions could increase the feasibility of the extraction process, leading to antioxidant extracts with lower energy or cost input, and higher suitability for further food use. The recovery of phenolic antioxidants from the peels of processed apples could be a valuable alternative to traditional disposal routes (including landfill), in particular for cooking varieties. The recycling process could enhance the growth of traditional culinary apple markets in UK and Ireland thanks to the new business opportunities for the peel-derived materials.
Starch residue samples from two Australian sweet potato varieties (Beauregard and Northern Star) and two Indonesian sweet potato varieties (Bis192 and Bis183), and a commercial sample of sweet potato starch residue, were studied for their pectins. Pectins were extracted using 0.1M HCl, 0.05M NaOH, 0.1M HCl/0.75% SHMP and 0.05M NaOH/0.75% SHMP. Hydrolysis of residual starch in the cell wall of sweet potato using heat stable α-amylase and amyloglucosidase was employed prior to pectin extraction to eliminate starch contamination. Pectins were characterised for yield, galacturonic acid content (GA), and the degree of esterification (DE). Conventionally, pectin is characterized by titration, photometry and HPLC. However these methods are cumbersome and time consuming. On the other hand, 13C CP/MAS solid-state NMR, a non-destructive, efficient and direct method, has been found to be well-suited for these purposes since pectin has well-defined 13C NMR spectra. Therefore 13C CP/MAS solid state NMR was used for pectin determination. The pectin characteristics are dependent on variety and extraction process; however, the extraction methods gave variable results. Yields were between 7 and 30% of the cell wall. GA varied from 27 to 80% with the highest found in Bis192 extracted using NaOH/SHMP. DE varied between traceable and 57%. HCl extraction gave higher DE, while NaOH/SHMP caused demethylation. Overall, this study demonstrated that pectin from sweet potato starch residue is mainly low in methoxyl groups.
Due to the high foreign exchange spent on the importation of wheat and the need to combat issues of malnutrition in developing countries, cookies were produced from flour blends of fermented pigeon pea (FPF), germinated sorghum (GSF) and cocoyam (CF). Proximate composition of the cookies revealed that cookies made with 100%FPF had the highest protein content of 16.13% while cookies made with 100%CF had the least protein value of 6.40%. The antinutritional factors investigated in the cookies were low and within allowable limits. The nutritional quality evaluated by animal feeding experiments revealed that biological values (BV) of cookies ranged from 78.16% (for 100%CF) to 96.57% (for 33.3%FPF:33.3%GSF:33.3%CF); net protein utilization (NPU) values ranged from 70.08% (for 100%CF) to 92.98% (for 33.3%FPF:33.3%GSF:33.3%CF) while true digestibility (TD) ranged from 89.53%(for 100%CF) to 97.88% (for 66.6%FPF:16.7%GSF:16.7%CF). The results obtained suggest that cookies of good nutritional value can be produced from these locally available crops.
The effects of enrichment of “gari” semolina with three different types of soy-melon protein supplements during toasting of “gari” were studied. Three protein supplements (Full fat, Defatted and Milk residue) were toasted together separately with the grated, dewatered and sifted cassava mash after fermentation (soak-mix method). After toasting and cooling, the samples were subjected to physico-chemical analyses. Results showed that enrichment increased the protein, fat and ash contents, and the pH values, while the hydrocyanic acid content, titratable acidity reduced generally. Enrichment increased the protein content from 2.81% in the control gari to a range of 15.3% - 23.5% in the enriched samples. The fat increased from 3.24% to a range of 4.13% - 13.50%; while the ash content increased from 1.18% to a range of 1.96% to 3.47%. Hydrocyanic acid was significantly (P ≤ 0.05) reduced from 13.5mg/kg to a range of 6.70mg/kg -12.5mg/kg in the enriched products. The pH increased from 3.62 to a range of 4.86 - 5.25 while the acidity correspondingly reduced from 0,46 in the control gari to a minimum value of 0.36% lactic acid in the sample toasted together with defatted soy-melon meal. From the result it could be concluded that enrichment improved the nutrient quality of “gari” especially the protein, fat and ash contents. It also reduced the hydrocyanic acid content, thereby producing “gari” of higher quality and better safety. The acidity of the enriched samples was however reduced thus lowering the sourness of “gari”. This may be an advantage for people who are not used to the sour taste of “gari”. Of all the three soy-melon “gari” samples, the sample enriched with defatted supplement had been shown to have the highest protein and ash contents, the lowest crude fat and acidity than other enriched gari samples. It had also been shown to have better wettability, water holding capacity, and ability to disperse in water. It also had better swelling and reconstitution indices than “gari” enriched with full fat and milk residue supplements.