Recycling of Citric Acid Waste for Potential Use as Animal Feed through Fermentation with Lactic Acid Bacteria and a Mixture of Fibrolytic Enzymes.

Once improperly managed, the citric acid production industry generates waste, which contributes to pollution and other environmental issues. We proposed that, with sufficient quality improvement, citric acid by-product (CAP) might be used for animal feed, thereby reducing the environmental impact. The aim of the present study was to ferment citric acid by-product (CAP) by inoculation with lactic acid bacteria (LAB) and a fibrolytic enzyme mixture for quality improvement and crude fiber reduction in the waste products. LAB inoculants were L. casei TH14, and the additive enzyme used was a fibrolytic enzyme mixture (glucanase, pectinase, and carboxymethylcellulase) of a small-scale fermentation method. The seven treatments employed in this study were as follows: (1) control (untreated), (2) CAP-inoculated L. casei TH14 at 0.01% DM, (3) CAP-inoculated L. casei TH14 at 0.05% DM, (4) CAP-inoculated enzymes at 0.01% DM, (5) CAP-inoculated enzymes at 0.05% DM, (6) CAP-inoculated L. casei TH14 at 0.01% DM with enzymes at 0.01% DM, and (7) CAP-inoculated L. casei TH14 at 0.05% DM with enzymes at 0.05% DM. The samples were taken on days 1, 7, 14, 21, and 28 of ensiling, both before and after. Four replications were used. The results of the chemical composition of the CAP before and after ensilage inoculated with L. casei TH14 did not show any differences in crude protein, ether extract, ash, or gross energy, but the enzymes significantly (p < 0.05) decreased crude fiber and increased nitrogen-free extract. The combination was especially effective at improving the characteristics of CAP, with a reduction in crude fiber from 21.98% to 22.69%, of neutral detergent fiber (NDF) from 16.01% to 17.54%, and of acid detergent fiber (ADF) from 13.75% to 16.19%. Furthermore, the combination of L. casei TH14 and the enzyme increased crude protein from 1.75% to 2.24% at 28 days of ensiling. Therefore, CAP-inoculated L. casei TH14 did not change in chemical composition, while crude fiber, NDF, and ADF decreased when CAP was inoculated with enzyme. The combination of L. casei TH14 and the enzyme is more effective at improving chemical composition and reducing crude fiber and enhancing carbohydrate breakdown in the CAP. Finally, by enhancing the CAP's quality, it may be possible to use it in animal feed and minimize its impact on the environment.

Investigation of Citric Acid By-Products from Rice Produced by Microbial Fermentation on Growth Performance and Villi Histology of Thai Broiler Chicken (KKU 1).

This study was conducted with Thai broiler chicken (KKU 1) to investigate the effect of citric acid by-products from rice (CABR) on growth performance and villi histology. A total of 192 broiler chicks were subject to three dietary treatments, including 0% CABR, 3% and 6% of dry matter. Body weight gains, feed intake, feed conversion ratio, survival rate, and production index (body weight gain, feed intake, feed conversion ratio, survival rates, and productive index, respectively) were considered for growth performance evaluation. Villi height (µm), crypt depth (µm), and villi: crypt ratio were recorded for the villi histological measurement. The performance did not show a significant effect when compared with the control group during at ages ranging from 1 to 56 days. Villi histology indicate a significant effect on villi height (µm), crypt depth (µm), and villi: crypt of broiler chicks compared with the control group. Also, the use of 3% CABR caused a reduction microbial contamination in chicken fecal matter. In conclusion, supplementation of CABR had no negative effects on growth performance of Thai broiler chicken (KKU 1). Also, the addition of 3% CABR to the feed might help reduce fecal microbial contamination and affect the villi histology of Thai broiler chickens (KKU 1).

A study on citric acid by-product as an energy source for Japanese quail.

The increasing worldwide production of citric acid by the fermentation of substrates for use as a flavoring and a preservative in foods has resulted in the generation of large amounts of waste and by-products from fermented. There is a challenge to reduce the waste from these products by using them as animal feed. An experiment was conducted to study the utilization of citric acid by-products (CABP) as a feed ingredient in Japanese quail diets. A total of 560 1-day-old quail chicks were randomly distributed into five groups, with CABP included at 0, 3, 6, 9, and 12% of the diets. Each treatment had four replicate pens of 28 birds per pen throughout the 42-day trial period. CABP inclusion at 9 or 12% of the diet, respectively, resulted in a decrease in feed intake of 5.90 and 9.52%, body weight of 5.67 and 9.16%, and body weight gain of 5.44 and 9.97%, compared with the control diet (p < 0.05). Carcass traits and relative organ weights were not significantly different among the treatments (p > 0.05). The 12% CABP group showed a decrease in the digestibility of crude protein and apparent metabolizable energy, but there was an increase in the amount of crude fiber compared with the control diet (p < 0.05). The utilization of CABP in diets can reduce feed costs leading to increased investment returns. In conclusion, CABP can be included at up to 6% of quail diets without significant effects on growth performance or nutrient digestibility.

Evaluation of physical and chemical properties of citric acid industrial waste.

This study aimed to evaluate physical and chemical properties and nutritive values of citric acid by-product (CABP) from cassava and to compare its properties with those of cassava root meal (CRM). The physical properties analyzed were color, bulk density, angle of repose, particle size distribution, and ultrastructure morphology. The chemical properties were determined using proximate analysis. Regarding the physical results, the CABP's color was darker, and its bulk density was greater by approximately 64.18% than those of the CRM (p < 0.05). The CABP's angle of repose was significantly lower (p < 0.05) with a freer flow, and the particle size was classified as small with fewer polygonal starch granules but more than the CRM. Regarding the chemical composition results, the CABP contained 0.71% citric acid with pH 4.68 whereas crude protein, ether extract, crude fiber, and gross energy were 6.11%, 2.39%, 18.26%, and 3588.10 kcal/kg, respectively. CABP showed greater and significantly different crude proteins and ether extracts but less gross energy than the CRM (p < 0.05). The results imply that the CABP could be an alternative energy source and used as a CRM substitution in animal feed formulation.