Waste Beer Research Articles

Preparation and characterization of insoluble β-glucan from waste beer yeast

The management of brewery waste, particularly waste brewer's yeast, has posed a significant environmental and economic challenge. This study proposed an approach to valorize waste brewer's yeast by extracting β-glucan. The key phases of the research included yeast autolysis, alkaline treatment and optimization of the β-glucan purification conditions. The findings revealed that a 0.7 % NaOH concentration at 80 °C for 2.6 h was the most effective for impurity removal. In the comparative analysis, it was confirmed that extraction at 80 % DMSO concentration with a 30:1 solid-liquid ratio at 80 °C for 30 min was the optimal condition for obtaining high-purity β-glucan. The process yielded a β-glucan high purity of 95.84 ± 1.15 % and a yield of 5.56 ± 0.34 % based on the wet weight after centrifugation. The structure was analyzed using TLC, FTIR and NMR. The extracts are polysaccharides composed of glucose monomers linked by β-glycosidic bonds. In addition, It has demonstrated significant anti-inflammatory properties in vitro and can be developed as a functional food. This study provides a feasible and efficient solution for the sustainable utilization of waste brewer's yeast, contributing to environmental sustainability and offering economic benefits for the brewing industry.

Beer Waste as a Feed Additive: Impacts on the Health and Performance of Sheep

Beer Waste as a Feed Additive: Impacts on the Health and Performance of Sheep

Optimization of Production Methods for Black Soldier Fly Larvae (Hermetia illucens L.) in Burkina Faso.

Larvae of Hermetia illucens are a valuable source of protein for animal feed that can be produced by exposing animal and agro-industrial wastes to naturally occurring flies. The objective of this study was to improve techniques for obtaining H. illucens larvae to feed livestock in Burkina Faso. An experiment was conducted to determine the most favourable substrates and seasons for larval production. The substrates used were poultry manure, local beer waste, local beer waste mixed with poultry manure, cottonseed cake, and industrial brewery waste mixed with poultry manure. The production of larvae was carried out in four different seasons. The effect of the container's oviposition area (0.07 m2, 0.09 m2, and 0.11 m2) and the type of container (terracotta, plastic, and iron) on larval production was also assessed. The produced larval biomass was high during, or just after, the rainy season but very low during the cool dry and hot dry seasons. Yields were higher with local beer waste mixed with poultry manure followed by local beer waste and cottonseed cake. The average mass of H. illucens larvae increased slightly with the oviposition area for the same amount of substrate. Iron and terracotta containers provided better results than plastic containers. The suitability of this production method for H. illucens larvae production is discussed.

Effect of food industry by-products on bacterial cellulose production and its structural properties

The advances in bioprocess design, genetic engineering, and media optimization have enabled enhanced bacterial cellulose (BC) production and its application for diverse purposes. Following the requirements of a bioeconomy, numerous approaches were conducted to investigate alternative carbon or nitrogen sources from industrial by-products for BC biosynthesis. They can, however, not only affect the BC production but also its properties. Beet molasses, vinasse, and waste beer fermentation broth (WBFB) have thus been investigated in single and combined approaches for their BC production potential and effects on structural properties using Komagataeibacter xylinus DSM 2325. Therefore, the composition of each complex component was initially analyzed for total organic carbon (TOC), total bound nitrogen (TNb), sugars, organic acids, and alcohols. The polymer properties were characterized via gel permeation chromatography and X-ray diffraction. In dynamic shake flask cultivations, the exchange of Hestrin-Schramm (HS) medium components for a combination of all three complex substrates on a TOC- or TNb-based quantity resulted in the highest BC concentration (8.2 g L−1). Comparable concentrations were achieved when combining molasses and WBFB (8.1 g L−1). Each investigated complex component led to differing degrees of polymerization (DPn: 2751−4601) and BC crystallinities (26−58%) in comparison to HS medium. Beet molasses and vinasse were found to decrease the polymer crystallinity but induce higher DPn whereas the opposite occurred for WBFB. This study thus highlights beneficial effects of food industry by-products for BC biosynthesis and elucidates concomitantly occurring structural polymer alterations to enable further studies dealing with alternative substrates for structurally tailored BC production.

Microencapsulation of β-carotene using barley residue proteins from beer waste as coating material

This study aimed to produce and characterise microparticles produced from barley residue proteins (BRP) enriched with β-carotene. The microparticles were obtained by freeze-drying five emulsion formulations with 0.5% w/w whey protein concentrate and different concentrations of maltodextrin and BRP (0, 1.5, 3.0, 4.5 and 6.0% w/w), with the dispersed phase consisting of corn oil enriched with β-carotene. The mixtures were mechanically mixed and sonicated, the formed emulsions were freeze-drying. The microparticles obtained were tested for encapsulation efficiency, humidity, hygroscopicity, apparent density, scanning electron microscopy (SEM), accelerated stability and bioaccessibility. Microparticles produced with the emulsion containing 6% w/w BRP had lower moisture content (3.47 ± 0.05%), higher encapsulation efficiency (69.11 ± 3.36%), bioaccessibility value of 84.1% and greater β-carotene protection against thermal degradation. SEM analysis showed that microparticles had sizes ranging from 74.4 to 244.8 µm. These results show that BRP are viable for the microencapsulation of bioactive compounds by freeze-drying.

Process Optimization, Amino Acid Composition, and Antioxidant Activities of Protein and Polypeptide Extracted from Waste Beer Yeast

Repurposing of waste beer yeast (WBY) that a main by-product of brewing industry has attracted considerable attention in recent years. In this study, the protein and polypeptide were extracted by ultrasonic-assisted extraction and enzymatic hydrolysis with process optimization, which resulted in a maximum yield of 73.94% and 61.24%, respectively. Both protein and polypeptide of WBY were composed of 17 Amino acids (AA) that included seven essential amino acids (EAA), and typically rich in glutamic acid (Glu) (6.46% and 6.13%) and glycine (Gly) (5.26% and 6.02%). AA score (AAS) revealed that the threonine (Thr) and SAA (methionine + cysteine) were the limiting AA of WBY protein and polypeptide. Furthermore, the antioxidant activities of WBY polypeptide that lower than 10 kDa against hydroxyl radical, DPPH radical, and ABTS radical were 95.10%, 98.37%, and 69.41%, respectively, which was significantly higher than that of WBY protein (25–50 kDa). Therefore, the protein and polypeptide extracted from WBY can be a source of high-quality AA applying in food and feed industry. Due to small molecular weight, abundant AA, and great antioxidant activity, WBY polypeptide can be promisingly used as functional additives in the pharmaceutical and healthcare industry.

Assessing the potential of Chlorella sp. for treatment and resource utilization of brewery wastewater coupled with bioproduct production

Wastewater from various industries is the ideal substrate for the cultivation of microalgae, leading to efficient wastewater treatment and the production of a valuable microalgal biomass. However, further research is needed before wastewater can be used and treated on a large scale. The purpose of the paper was to explore the cultivation of the microalga Chlorella sp. in brewery wastewater (BWW) as well as under applied treatments of cultivating mode, dilution ratios, pretreatment method, and feeding strategies, and investigate the potential value of biomass obtained. Cultivation in BWW was initiated from 30% (v/v) loading while enrichment with 10% waste beer yeast supernatant (WYS) increased specific growth rate (μ) and biomass production, reaching 0.12 d−1 and 1.77 g L−1, respectively. Increasing BWW concentration up to 50% with 10% WYS can obtain the maximum biomass concentration of 2.03 g L−1 that is 0.14 g L−1 higher than 1.89 g L−1 of biomass in BG11. Even when the concentration of BWW reached 100%, biomass production can still reach 1.96 g L−1. In terms of BWW remediation, the maximum removal of ammonia nitrogen (NH4+-N), chemical oxygen demand, total nitrogen, and total phosphorus reached 94.38%, 88.52%, 96.71%, and 98.68%, respectively. Furthermore, the applied conditions determined the composition of Chlorella sp. biomass, which was mostly rich in lipid and carbohydrates. The maximum lipid, carbohydrate, and protein contents were 36.19%, 36.51%, and 19.77%, respectively, depending on culture conditions, and heterotrophic conditions were beneficial to protein accumulation in Chlorella sp. Photosynthetic fluorescence parameter electron transport rate was positively correlated with the biomass concentration of Chlorella sp.

Assessment of Product Yield and Characteristics of Biocrude from Hydrothermal Liquefaction

Biomass is a promising renewable energy source for fuel conversion. Hydrothermal liquefaction technology converts biomass into an energy-rich biofuel called biocrude which can potentially substitute fossil fuels. In this study, wet biomass namely water hyacinth, banana pseudostem, banana peduncle, wine waste and beer waste were investigated for biocrude production. The biomass macro molecules underwent anaerobic thermochemical disintegration to yield biocrude in the range of 7.3 to 16% at the hydrothermal liquefaction temperature and pressure of 275 ºC and 15 MPa respectively. Wine waste showed higher biocrude yield (16%) among the selected biomass materials with aqueous phase (63%) and char (3%) as by products. The recovered biocrude showed good quality fuel properties similar to diesel and bio-diesel with heating value of about 30 MJ kg-1. GCMS and FTIR analyses proved the biocrude to be rich in aliphatic and aromatic fuel and chemical derivatives of alkenes, alcohols, ketones and amines which necessitate its potential to drop in advanced fuels and chemicals for supplementing conventional resources.

Recycling Crushed Waste Beer Bottle Glass in Fired Clay Bricks

Waste glass is a readily available domestic material. Each year, around 257,000 tonnes of glass waste are produced in Victoria, and the majority is glass packings. Typically, mixed waste glass cullet is deposited in landfills due to the limited recycling techniques. As a result, landfills are facing a growing issue. Therefore, this study investigates the addition of waste beer bottle glass (BG) in fired clay bricks and examines the effects of varying firing temperatures on the physical and mechanical properties of the manufactured samples. Clay bricks containing 10% BG at a firing temperature of 950 °C depicted similar compressive strength results (41 MPa) to the control samples (42 MPa). The results of all tested bricks were found to be below the water absorption limit of 17%. The thermal conductivity of the bricks incorporating BG was investigated, and it was found that the thermal performance improved with the decreasing firing temperature. Moreover, an initial rate of absorption (IRA), XRD, and XRF analysis was conducted. The experimental results have been discussed and compared with the recommended acceptable properties for standard bricks.

Feeding rice fermented beer waste improves growth performance, nutrient digestibility and nitrogen utilization in growing rabbits.

This study was conducted to investigate the effects of dietary rice brewer waste (RBW) on growth performance, nutrient utilization and nitrogen balance in growing rabbits. Thirty growing rabbits (758±25.7g initial body weight) were randomly assigned to control and four treatment groups (containing RBW) in a completely randomized design with six rabbits per group. The study lasted 6weeks for measurements of feed intake and growth performance followed by a five-day metabolic trial to determine nutrient digestibility and nitrogen balance. The five diets contained RBW at 0% RBW (control group), unsterilized RBW at 10% and 20% and sterilized RBW at 10% and 20% in the concentrates. The average daily body weight gain (ADG) in the 20% unsterilized RBW group was higher (p<0.01) than the control group. No statistically significant difference (p=0.089) of ADG was observed for the control vs. the sterilized groups, but the overall ADG was better (p=0.044) in the unsterilized RBW groups than the sterilized RBW groups. The daily dry matter intake in unsterilized and sterilized RBW groups was higher (p<0.01) than the control group. However, no difference (p=0.22) was found between the unsterilized and sterilized RBW. The feed conversion ratio (FCR) was lower for the unsterilized RBW groups vs. the control group (p=0.041), but there was no difference of FCR in the control vs. sterilized RBW groups (p=0.37) and the unsterilized RBW groups vs. unsterilized RBW groups (p=0.14). The digestibility of organic matter, crude protein and crude fibre was greater (p<0.01) in the unsterilized and sterilized RBW groups than the control group. The nitrogen balance and efficiency of nitrogen utilization were also higher in the unsterilized and sterilized RBW groups than the control group (p<0.01). The study showed that the dietary RBW could improve growth performance and nutrient utilization in growing rabbits with superior responses for the unsterilized RBW.

Dynamic Simulation and Modelling of Methane Production Process for Habesha Beer Waste Water Treatment Process Using Aspen Plus Software

Brewery production process is one of the biggest economical sources in Ethiopia, there are different brands in beer industry in the country, such as Dashen, Balageru, Heineken, and Habesha Brewery Company, in such factories the modern technology treatment was performed in Habesha brewery. All beer industrial processes require large amounts of water and produce significant amounts of wastewater. Cleaner production is having an impact on these industries and today they are looking forward to zero discharge. In Habesha brewery, the generation of wastewater is coming under all departments, such as from brew house, filtration utility, and packaging rooms. The composition of brewery waste water effluent was sulphate, H2S, CO2, sugar, and methane, etc. Habesha Brewery has given value highly the quality, taste, and drinkability of their beer. Production of methane from waste water during the treatment process was not applied in Habesha brewery industry due to the low treatment of methane and lack of technology to recover methane as an energy source. Through anaerobic digestion of organic waste materials provides an alternative environmentally friendly renewable energy. Methane production from digestion of brewery wastewater was improved using chemical methods, using aspen plus dynamics simulation the model of methane production recovery system was modelled, and brewery waste was taken into the reactor in its own behavior was evaluated under atmospheric conditions, 25°C, 30°C & at 1 atmosphere. For all substrates, total solids, biological oxygen demand, chemical oxygen demand, temperature, total nitrogen, total phosphorus, and pH were measured before and after digestion. Wastewater by volume was taken fully into the digester. All measured physico-chemical parameters of the sample substrate significantly varied before and after anaerobic digestion. Methane was measured for all samples periodically starting from the effluent was started. In all substrates. Assessment of cumulative methane production revealed that the substrate at a temperature 30°C, pH 6.5 (0.0013 hl /0.008 hL sample of waste water) and after 4 days sample 25°C, PH 7.5 (0.001625 hL/0.008 hL sample) showed the highest Methane production and the lowest was in the last day volume waste water, 35°C temperature and pH of 6 (0.00125 hL/0.008 hL sample of waste water). The results indicated that the methane amount was affected by H2S, CO2, sugar, and other behaviors of brewery waste water effluent during the digestion process.

The Optimization of Packaging System Process Parameters Using Taguchi Method

Packaging systems constitute substantially to product cost, its safety, and optimization. Unfortunately, no previous optimization studies have examined the packaging system in a bottling process plant for the unique, developing country environment. Consequently, the Taguchi method is applied to optimize a process plant's packaging system in a Nigerian plant's real-life situation. Optimal combinations of packaging system parameters that minimize product waste are created. An L4 (23) Taguchi orthogonal array was selected to analyze the data, and signal-to-noise ratios were computed for each experiment's run. Since the aim was to minimize beer waste, the ‘the-smaller-the-better’ signal-to-noise ratio was chosen in the analysis. S/N ratio plots revealed the optimum settings to obtain minimal product waste, namely, A2, B1, and C2 from the main effects plot for signal-to-noise ratios. A two-way ANOVA was performed on the significant factors to determine their percentage contributions to the response (product waste). Through Taguchi's innovative approach, the feasibility of optimizing the packaging process parameters was demonstrated and validated.

Investigating characteristics and possible origins of off-odor substances in various yeast extract products.

Yeast extract (YE) is rich in amino acids, nucleotides, peptides, and other flavor substances, and is a natural nutrient, umami, and flavor enhancer. However, certain YE samples impart a yeasty flavor that affects the quality parameters of YE. We compared solid-phase microextraction (SPME), solvent-assisted evaporation (SAFE), dynamic headspace sample preparation (DHS), stir bar sorptive extraction (SBSE), and other pretreatment methods for the extraction of volatiles substances in YE. SPME was selected as a suitable extraction method, and aroma extract dilution analysis (AEDA) was combined with gas chromatography-olfactometry-mass spectrometry (GC-O-MS) for identification of key odor-active compounds in 23 YE samples. The yeast off-odor substances were screened from these compounds. Principal component analysis (PCA) was used to investigate the relationship between strains and the processing of YE products and their yeasty flavor. PRACTICAL APPLICATIONS: YE is prepared primarily from baker's yeast or waste beer yeast by autolysis or enzymatic hydrolysis, and is rich in nucleotides, peptides, amino acids, and other flavor compounds. It is used globally as a common umami and flavor enhancer. However, consumers have observed that YE imparts a certain yeasty flavor that influences the overall flavor negatively. Hence, the yeasty flavor-imparting substances from 23 YE samples were investigated in this study, and the observations (including strains, processing techniques, etc.) were integrated to explain the relationship between the yeasty flavor of the YE products with strain (different yeast strain for production) or processing of YE products (enzymes used, enzymatic hydrolysis conditions, composition of products, concentration conditions of YE, etc.), or storage conditions (temperature, humidity, duration, package, etc.), providing a scientific basis for removal/lowering or masking of yeasty flavor and the improvement of flavor quality of YE products.

The impact of biodegradable carbon sources on nutrients removal in post-denitrification biofilm reactors

Wastewater from households wastewater treatment plants (HWWTP) is discharged to the ground or to the surface waters. Special consideration should be given to the improvement of HWWTP effectiveness, particularly in relation to nutrients. The addition of biodegradable carbon sources to biofilm reactor, can enhance microbial activity but may also lead to filling clogging. The study aimed to compare 3 different organic substrates: acetic acid (commonly applied)and two untypical - citric acid and waste beer, under the same operational conditions in a post-denitrification biofilm reactor. The study investigated the impact of a type of organic substrate, low pH and time on: (1) biofilm growth, (2) the characteristics of extracellular polymeric substances (EPS), (3) the kinetics of nutrients removal and (4) reactor clogging. Results were referred to (5) the effectiveness of nutrients removal. The study demonstrated that low pH assured the development of a thinbiofilm. Citric acid ensured the lowest biomass volume, being by 53% lower than in the reactor with acetic acid and by as much as 61% lower than in the reactor with waste beer. The soluble EPS fraction prevailed in the total EPS in all reactors. The content of the tightly bound EPS fraction ranged from 26.93% (citric acid) to 36.32% (waste beer). Investigations showed also a high ratio of exoproteins to polysaccharide in all fractions, which indicated a significant role of proteins in developing a highly-proliferating biofilm. The treated wastewater met requirements of Polish regulations concerning COD and nitrogen concentrations.

The effect of an initial high-quality feeding regime on the survival of Gryllus bimaculatus (black cricket) on bio-waste

Previous studies have led to claims that insects can offer a solution to several food security hurdles, one of which is the processing of food waste. However, although it has been demonstrated that some insects survive well on bio-waste (e.g. Hermetia illucens), no study, has to date, demonstrated success rearing species more commonly used for human consumption, such as crickets, on biowaste from hatching. This trial aimed to establish if the black cricket, Gryllus bimaculatus, can be reared successfully on bio-waste from hatching. Since, in other livestock sectors it has been established that nutritional requirements vary with age and that diet must be altered accordingly to achieve the best growth, e.g. chick feed to layer mash in chickens, the present trial used a similar feeding regime of an initially high-quality feed to see if this allowed the subsequent survival of crickets on low quality bio-waste products. Pilot trials have demonstrated poor to no survival on beer waste and cow manure and mid-level survival on unprocessed vegetable waste with chicken feed as the control. Based on this, feed regimes of either 1 or 2 weeks high quality feed (chicken feed) and then either 2 or 3 weeks of low quality feed (beer waste or vegetable waste) were tested. Results showed that even 1 week of high quality feed makes a significant difference in survival and end size of crickets subsequently reared on low-quality bio-waste.

Preparation of magnetic ion imprinted polymer with waste beer yeast as functional monomer for Cd(ii) adsorption and detection.

In this work, a magnetic ion imprinted polymer (MIIP) with specific recognition capability toward cadmium was prepared by a sol–gel method using waste beer yeast, which is a macromolecule biomass, as a functional monomer. The obtained Cd(ii)-MIIP was characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and adsorption experiments. Then, a MIIP adsorbent based magnetic solid phase extraction (MSPE)-graphite furnace atomic absorption (GFAA) method was established to analyze the cadmium content in food and environmental samples. The maximum cadmium adsorption capacities by the MIIP and magnetic non-imprinted polymer (MNIP) were 62.74 and 32.38 mg g−1, respectively. The absorption by the MIIP was fitted using a pseudo-second-order kinetic model. The Cd(ii)-MIIP demonstrated superior absorption capability for selective removal cadmium. The recovery rate of the MIIP was 90.7% after four adsorption–desorption cycles. The calculated Cd(ii) detection limit (S/N = 3) was 0.18 μg L−1 with the relative standard deviation (RSD) equal to ∼3.5% for 10 μg L−1 of Cd(ii) standard solution. Our proposed method was successfully used in detecting Cd(ii) in aqueous samples. The results obtained in this work suggest that the Cd(ii)-MIIPs might be promising adsorbents to remove harmful cadmium ions from aqueous samples.

Ambient-temperature co-digestion of low-solids municipal and industrial waste mixtures: Insights from molecular analyses

ABSTRACTThe performance of ambient temperature anaerobic co-digestion was investigated for mixtures of six substrates: canned tomato and salsa waste, portable toilet waste, septic tank waste, winery waste, beer and cider waste, and fats, oils, and grease (FOG). Laboratory semi-continuous reactor studies and molecular biological analyses revealed that beer/winery, and tomato/FOG/winery/beer mixtures resulted in the best performance in terms of biogas production (515 and 371 mL CH4/g VS, respectively) and methanogenic populations. A portable toilet/septage mixture resulted in the overall poorest performance and inhibition of microbial activity was evident. Average methane content was ~70% for all mixtures tested. The findings of this study reveal that healthy methanogen populations were present, further supporting the feasibility of biogas production via the novel feedstock mixtures in ambient temperature lagoons.Implications: Disposal of septic tank waste and other high chemical oxygen demand (COD) 10 industrial food processing waste at a small wastewater treatment plant is uncommon, because it can upset the treatment process and requires additional power for treatment. Ambient-temperature covered lagoon digesters can be an alternative low-cost technology for co-digestion of these recalcitrant waste streams while generating bioenergy. The results of this study demonstrated that there is potential for implementation of unheated covered lagoon digester systems 15 for conversion of liquid wastes for production of renewable biomethane while eliminating the need to treat these wastes at a wastewater treatment plant.

Biosorption of heavy metal copper (Cu2+) by Saccharomyces cerevisiae

This research aims to study the optimum effect of contact time and pH adsorption of copper (Cu2+) from electroplating industry waste by dried beer waste S.cerevisiae. This research conducted using batch culture with pH variation 2,3,4,5, and 6, contact time variation 60, 90, 120, 150, 180 minutes, 150 rpm at room temperature (± 28°C), initial Cu2+ concentration 33,746 mg/l, and biosorbent mass 200 mg & 500 mg. The adsorption of heavy metal ions Cu2+ occurs in all variations of pH and contact time at optimum pH. The optimum adsorption occurs at pH 4 with contact time 120 minutes for both 200 mg (41.60%) and 500 mg (61.04%) beer waste biosorbent. Cell morphology seen with Scanning Electron Microscope (SEM) analysis shows the change of cell wall that gets damaged from Cu2+ adsorption. It also proved by the decreased concentration of initial high concentration carboxyl groups. The adsorption process of this research complies to Freundlich Isotherm with R2 value closest to 1 and followed first order kinetic.

Residual brewing yeast as a source of polyphenols: Extraction, identification and quantification by chromatographic and chemometric tools

A method combining aqueous extraction, reversed-phase high-performance capillary liquid chromatography with photodiode array detection (cLC-DAD) and chemometric tools, was developed to determine phenolic compounds in residual brewing yeast. The effect of temperature, nature of extraction solvent and method for separation of extract solution were studied to optimize the extraction conditions on the basis of total phenolic content (TPC), total flavonoids content (TFC) and antioxidant capacity. Polyphenols were determined by cLC-DAD. Flavonols as rutin and kaempferol, flavonoids as naringin, phenolic acids as gallic acid and antioxidants as trans-ferulic and p-coumaric acids were found and quantified in the brewing residue. Data were subjected to evaluation using multifactor ANOVA and principal component analysis (PCA), both showing that lyophilization pretreatment affects the content of individual polyphenols and that residual brewing yeast contains higher polyphenol amounts than the liquid beer waste. The obtained results suggest that residual brewing yeast could be a source of polyphenols.

Attraction ofBactrocera cucurbitaeandBactrocera dorsalis(Diptera: Tephritidae) to Beer Waste and Other Protein Sources Laced with Ammonium Acetate

Adult tephritid fruit fly females require protein sources for adequate egg production, and ammonia and its derivatives serve as volatile cues to locate protein-rich food. The attractiveness of beer waste and the commercially available baits Nu-Lure® Insect Bait, Buminal®, and Bugs for Bugs® Fruit Fly Bait with and without ammonium acetate or ammonium carbonate to males and females of Bactrocera dorsalis (Hendel) and B. cucurbitae (Coquillett) (Diptera: Tephritidae) was quantified in semi-field cage studies in Hawaii. Evaluations also compared the relative attractiveness of the baits to that of the standard bait GF-120® NF Naturalyte® Fruit Fly Bait. Our findings indicate that ammonium carbonate did not exert any effect on the response of B. cucurbitae or B. dorsalis to the protein baits evaluated and that the addition of ammonium acetate to beer waste and to the commercially available bait Bugs for Bugs® can improve bait attractiveness in particular to females of B. cucurbitae. Beer waste laced with ammonium acetate performed as well as the standard fruit fly bait GF-120®. There were variations in the level and type of response between B. cucurbitae and B. dorsalis, and such variability was dependent upon the type of bait being evaluated. For example, there were several instances where baits lacking ammonium acetate (e.g., beer waste and Nu-Lure® for B. cucurbitae; Buminal® for B. dorsalis) were as attractive as GF-120®. Results are discussed in light of potential applications associated with the use of beer waste as a low-cost, readily available material for fruit fly monitoring and suppression.